Clinical Review

OBG Management Senior Editor Janelle Yates contributed to this article.

Hear Dr. Pinkerton discuss this article

The Women’s Health Initiative (WHI) caused a sea change in women’s attitudes toward menopausal hormone therapy and aroused many fears—not always rational—that remain almost palpable today. One study of the aftermath of the WHI found that 70% of women who were taking hormone therapy discontinued it, and 26% of women lost confidence in medical recommendations in general.¹

Into the chaos stepped Suzanne Somers, Michael Platt, and other celebrities, touting the benefits of a new kind of hormone: bioidentical. You don’t have to read Somers’ bestseller, The Sexy Years, to encounter the claims it makes on behalf of bioidenticals; the cover itself makes them clear: Discover the Hormone Connection—The Secret to Fabulous Sex, Great Health and Vitality, for Women and Men. Since publication of the book, the demand for bioidentical hormones has only increased, as women remain fearful about conventional hormone therapy.

Many ObGyns regularly field requests from patients for specially compounded bioidentical regimens. In most cases, the women who ask for these drugs are poorly informed about their risks and willing to pay out of pocket to acquire them. JoAnn V. Pinkerton, MD, sees many of these patients at The Women’s Place Midlife Health Center in Charlottesville, Virginia. OBG Management recently sat down with Dr. Pinkerton to discuss her concerns about the growing ubiquity of compounded bioidentical hormones. In the Q&A that follows, we talk about what “bioidentical” actually means, whether these hormones are ever justified, common misconceptions about them, and other issues.

In a special accompanying commentary, former Food and Drug Administration (FDA) Senior Medical Officer Bruce Patsner, MD, JD, also weighs in on the issue.

What is “bioidentical”?

OBG MANAGEMENT: Let’s start with the basics. What does the word “bioidentical” mean? Is it a legitimate medical term?

DR. PINKERTON: Bioidentical hormones are exogenous hormones that are biochemically similar to those produced endogenously by the body or ovaries. These include estrone, estradiol, estriol, progesterone, testosterone, dehydroepiandrosterone (DHEA), and cortisol. The FDA has approved many prescription products that contain bioidentical hormones. However, the term “bioidentical” is often used to refer to custom-compounded hormones. The major difference between the FDA-approved prescription bioidentical hormone products and custom-compounded products is that the former are regulated by the FDA and tested for purity, potency, efficacy, and safety.

Bioidenticals are not “natural” hormones, although many consumers think they are. In reality, compounded bioidentical hormones and FDA-approved bioidentical hormones all come from the same precursors. They begin as soy products or wild yam and then get converted to the different hormones in a laboratory in Germany before finding their way to the various world markets.

The claim that all bioidentical hormones are bioengineered to contain the same chemical structure as natural female sex hormones is false. As one expert noted, “the term ‘bioidentical’ has become inappropriately synonymous with ‘natural’ or ‘not synthetic’ and should be redefined to correct patient misconceptions.”²

Common misconceptions

OBG MANAGEMENT: What are some of the other false impressions you encounter among patients who ask for bioidenticals?

DR. PINKERTON: That the hormones are safer or more effective than hormone therapy, that they carry no risks, and that they are as well-monitored as FDA-approved products, to name a few. (For more, see “10 erroneous beliefs patients have about compounded hormones”).

OBG MANAGEMENT: Where do these ideas originate?

DR. PINKERTON: They are propagated by self-proclaimed experts and celebrities or by laypersons and physicians who devote the bulk of their time to promoting these hormones, usually at considerable cost to the patient.

OBG MANAGEMENT: What are the risks of compounded bioidentical hormones?

DR. PINKERTON: According to FDA guidance for industry, in the absence of data about these hormones, the risks and benefits should be assumed to be identical to those of FDA-approved hormone therapies, with the caveat that we don’t know from batch to batch what a woman is receiving. However, they are not regulated or monitored by the FDA, so we are lacking testing for purity, potency, efficacy, and safety. When the FDA did analyze compounded bioidentical hormones, a significant percentage (34%) failed one or more standard quality tests.³ In comparison, FDA-approved drugs fail analytical testing at a rate of less than 2%.³

The problems with compounded hormones

BRUCE PATSNER, MD, JD
Dr. Patsner is Research Professor of Law at the University of Houston Law Center in Houston, Tex. He served as Senior Medical Officer at the US Food and Drug Administration (FDA), where he was one of the agency’s experts on pharmacy compounding of prescription hormone drug therapy for the treatment of menopausal conditions.

The FDA has nothing against compounding pharmacies per se. Individualized preparation of a customized medication for a patient, based on a valid prescription, is an essential part of the practice of pharmacy. However, some actors in the pharmacy compounding business have taken the practice to a different level, not just in terms of the volume of business they do, but in the way compounded hormones are advertised and promoted. The courts aren’t necessarily interested in intervening in cases involving high volume alone. And when it comes to unsubstantiated claims of benefit, the FDA has found it difficult to assert jurisdiction over pharmacy compounding in general, making it hard to assert control over the advertising claims these pharmacies make on behalf of compounded drugs.

The result? The FDA has been unable to rein in claims that compounded prescription drugs are safer or better than commercially prepared medications. These drugs are probably as safe and effective as their manufactured counterparts, but there are no data to confirm this assumption.

What’s in a name?

“Bioidentical” isn’t a bona fide term. There is no definition of it in any medical dictionary; it’s just a name the industry cooked up, a catchy one at that. And when bioidenticals are advertised and promoted, the term “natural” is usually in close proximity. Most patients equate the word natural with plant-derived substances that have not been chemically altered. The fact is, many compounded prescription drugs are derived from plants—but they are also chemically altered.

Some applications are legitimate

A number of women use compounded medications because they make it possible to obtain hormone combinations that are not readily available in cream form. For example, if a patient wants testosterone as part of a cream of estrogen and progesterone, a compounded product is the only option.

Show me the data

No studies have compared compounded drugs with commercial drugs—and such studies are exceedingly unlikely. Compounding pharmacies have no incentive to conduct or participate in such studies. The pharmaceutical compounding industry is a multibillion-dollar enterprise in this country, and compounded prescription drugs for menopausal conditions are probably the biggest product outside of the oncology arena. Proponents of compounded hormones have a captive audience, so to speak, made up of women who don’t like commercial drug manufacturers or who prefer products that appear to be natural, or both.

The problem is that these women receive no package insert or prescription drug label with their hormones. Warning labels are not required because compounded drugs are not regulated by the FDA. Consumers are basically at the mercy of whatever claims they read on the Internet or in the lay literature, which tends to be written by people who have a financial interest in affiliating with the compounding industry. It’s a very frustrating situation for a lot of people.

Unintended consequences of the WHI

The Women’s Health Initiative (WHI) stirred demand for bioidentical hormones by casting the safety claims for some commercial hormone therapy products in a less than favorable light. That wasn’t the investigators’ intent, of course, and some of the findings of the WHI have since been questioned.

The goal of the WHI was to critically evaluate some of the touted health benefits of commercial hormone therapy prescription drugs, but, by questioning some of these claims, it inadvertently pushed a significant percentage of patients toward compounded prescription drugs—and we have no safety data on them.

No one knows exactly how many women were swayed, but the consensus is that they were, and no one’s been happy about that.

The main problem with the compounded hormones, as I see it, is that women who use them do not receive any written information from the compounding pharmacist about risks and benefits. Nor do they receive the black box warnings on FDA-approved estrogen therapy. I believe women need to be adequately educated about the potential risks and benefits, as well as the lack of efficacy data and quality control, if compounded products are requested. That means it’s up to the prescriber to educate the patient about the potential risks and benefits.

Rosenthal states that symptomatic menopausal women or those who fear breast cancer or heart disease can be considered a vulnerable population: “Patients do not have the background to decipher credible sources from noncredible sources.” False claims present convincing arguments for laypersons. A woman may be vulnerable to unsubstantiated claims by virtue of her symptoms and the anxiety and even depression that they can produce. Without comprehensive education, these women cannot be assumed to be adequately informed.

Let me put it in perspective. If a patient with a history of breast cancer complains about severe vaginal dryness that interferes with her sex life, I might decide to give her the smallest amount of topical estrogen that I can—for example, a dime-sized amount of estrogen to apply to her vulvar area twice a week. This amount of estrogen can’t be detected in her system with current assays. I know that some of it will be systemically absorbed, but it cannot be detected. When the patient buys that commercially prepared cream from the pharmacist, she will receive the same black box warning that comes with all systemic hormones since the WHI. However, if she goes to a compounding pharmacist with a prescription for bioidentical hormone therapy, she will not get the warning, regardless of the ingredients or dosage.

Are compounded bioidenticals ever justified?

OBG MANAGEMENT: According to the FDA, compounding of drug products is justified only when a practitioner finds that an FDA-approved drug does not meet the patient’s needs. Do you think this is ever really the case, given the availability of FDA-approved bioidentical hormone preparations?

DR. PINKERTON: In rare cases, compounding of bioidentical hormones is justified, such as when a patient cannot tolerate an FDA-approved product. The problem is that women have been especially concerned about the safety of hormone therapy since the WHI, and bioidentical hormones have been promoted as being safer than FDA-regulated preparations, despite the lack of evidence of their safety or efficacy in peer-reviewed literature. So many women request them.

In a recent commentary, Boothby and Doering call bioidentical hormone therapy “a panacea that lacks supportive evidence.” They say, “It’s our belief that pharmacists are compounding these with the best intentions, but they are ill informed regarding the lack of scientific underpinning associated with efficacy and safety.”³

OBG MANAGEMENT: Do you ever prescribe bioidentical hormones?

DR. PINKERTON: Yes, but rarely, and primarily for women who can’t tolerate FDA-approved hormones or who, after adequate information and education, refuse FDA-approved hormone therapy.

Is salivary hormone testing informative?

OBG MANAGEMENT: Many clinicians who prescribe bioidentical hormones base the dosage on salivary hormone testing. They claim that this allows them to offer individualized formulations. Is this a reliable claim?

DR. PINKERTON: No, it isn’t. Although compounded bioidentical hormone therapy is often prescribed on the basis of salivary hormone testing, there is no scientific evidence that a correlation exists between a patient’s symptoms and salivary hormones, or that salivary hormone testing reflects what is happening at the tissue level. As Fugh-Berman and Bythrow have observed, this type of testing is often used to convince asymptomatic consumers to use hormones—or symptomatic women to take higher dosages. That practice is likely to lead to adverse events.⁵ The practice also directly contradicts evidence-based guidelines, which recommend that hormone therapy be individualized on the basis of symptoms, not hormone levels.⁶

There are no published studies in the peer-reviewed literature that show that salivary testing is a reliable measure on which to safely and effectively base dosing decisions. Indeed, The Endocrine Society issued a position statement that notes, among other issues, that salivary hormone tests are “inaccurate and should not be considered reliable measures of hormones in the body.”⁷ The American College of Obstetricians and Gynecologists also advises against salivary testing, observing that:

• 1) there is no biologically meaningful relationship between salivary sex steroidal hormone concentrations and free serum hormone concentrations
• 2) there is large within-patient variability in salivary hormone concentrations. Salivary hormone levels vary depending on diet, time of day of testing, the specific hormone being tested, and other variables.³

Do bioidenticals protect against cancer?

OBG MANAGEMENT: Some reports mention the fact that many women believe that bioidentical hormones—specifically, estriol—can reduce their risk of breast and endometrial cancer. Is there any truth behind this belief?

DR. PINKERTON: Estriol is a weak estrogen. There is no evidence that, if it is given at a dosage high enough to relieve symptoms, it is any safer than estradiol.

In regard to endometrial cancer, if the exogenous estrogen—bioidentical or otherwise—is unopposed or inadequately opposed, the risk of endometrial cancer is elevated. The problem is that it is hard to determine whether estrogen is being adequately opposed, particularly when transdermal compounded progesterone is given, because the progesterone molecule is too large to be well-absorbed systemically.⁹

In regard to breast cancer, estriol is a less potent estrogen than estradiol, but it is believed to carry the same risks if it is dosed at effective levels. There is nothing about estriol per se in the peer-reviewed literature that shows that it protects against breast cancer.

The data on risk of breast cancer with estrogen therapy is confusing, with potentially higher risks if estrogen is combined with progestogen. Most of the data we have on estriol come from animals, but a study from 1980 in humans showed that, when older women with breast cancer were treated with estriol, 25% had increased growth of metastases.⁸

How do you monitor use of bioidentical hormones?

OBG MANAGEMENT: When you do prescribe a compounded bioidentical hormone, how do you monitor the patient?

DR. PINKERTON: First, I want to reiterate that I prescribe these hormones after considerable patient education about FDA-approved options and their potential risks. Second, when a patient needs or requests hormone therapy, I recommend conventional therapy. Only when she cannot tolerate or refuses FDA-approved drugs do I consider prescribing compounded bioidentical hormones—which, as I said earlier, are assumed to carry risks identical to those of FDA-approved hormones.

In some cases, I provide gynecologic care for patients who obtain compounded bioidentical hormones from other sources. What I will sometimes do, just to give myself some idea of how much estrogen they are getting, is to measure the peak and trough estradiol and estrone levels. That is, I measure the hormone level within 4 hours of the patient taking the drug to see how high it goes, and again about 12 hours later to see how low it goes. I measure both because estradiol may be peripherally converted to estrone.

Regrettably, we don’t know what to do about the various hormone levels. It isn’t like treating thyroid disorders; we normally dose estrogen therapy based on symptoms.

Who pays?

OBG MANAGEMENT: Who pays for salivary testing and compounded bioidentical hormones? Does health insurance cover them?

DR. PINKERTON: Like other “natural” products, compounded bioidenticals may cost more than their commercially prepared counterparts and often are not covered by insurance. In addition, prescribers may charge more for a “consultation” than do practitioners who accept insurance; they also may recommend salivary testing, which is expensive. Patients can end up paying large sums out of pocket.

As Rosenthal noted, many women do not appear to be concerned about the added costs.² That may be because compounded bioidentical hormone therapy is usually offered to economically advantaged patients.²

Ethical considerations

OBG MANAGEMENT: That raises an important question: What ethical considerations are inherent in the prescribing of compounded bioidenticals?

DR. PINKERTON: The fact that women who are able to pay out of pocket are the primary users of these drugs is one important point. In her analysis of the ethics surrounding bioidentical hormones, Rosenthal noted that the drugs remain “an unequal alternative, and any data collected would not be representative of the overall menopausal community.”²

A critical issue pointed out by Rosenthal is that perimenopausal and menopausal women may be particularly vulnerable to the unsubstantiated claims of purveyors of bio identical hormones. “A substantial number of women seek out bioidentical hormone replacement therapy to restore sexual well-being and functioning, in particular, who may be psychologically more vulnerable,” she writes.²

Another concern arises when the practitioner who prescribes bioidentical hormones also happens to sell them. This poses a potential conflict of interest and “violates professional ethical conduct.”²

OBG MANAGEMENT: Do physicians aggravate the problem when they accede to a patient’s request for compounded hormones?

DR. PINKERTON: Physicians and health-care providers need to stop and educate the patient about the lack of safety and efficacy data, the risks and benefits, and recognize the possibility that she has been influenced by unsubstantiated claims.

OBG Management Senior Editor Janelle Yates contributed to this article.

Hear Dr. Pinkerton discuss this article

The Women’s Health Initiative (WHI) caused a sea change in women’s attitudes toward menopausal hormone therapy and aroused many fears—not always rational—that remain almost palpable today. One study of the aftermath of the WHI found that 70% of women who were taking hormone therapy discontinued it, and 26% of women lost confidence in medical recommendations in general.¹

Into the chaos stepped Suzanne Somers, Michael Platt, and other celebrities, touting the benefits of a new kind of hormone: bioidentical. You don’t have to read Somers’ bestseller, The Sexy Years, to encounter the claims it makes on behalf of bioidenticals; the cover itself makes them clear: Discover the Hormone Connection—The Secret to Fabulous Sex, Great Health and Vitality, for Women and Men. Since publication of the book, the demand for bioidentical hormones has only increased, as women remain fearful about conventional hormone therapy.

Many ObGyns regularly field requests from patients for specially compounded bioidentical regimens. In most cases, the women who ask for these drugs are poorly informed about their risks and willing to pay out of pocket to acquire them. JoAnn V. Pinkerton, MD, sees many of these patients at The Women’s Place Midlife Health Center in Charlottesville, Virginia. OBG Management recently sat down with Dr. Pinkerton to discuss her concerns about the growing ubiquity of compounded bioidentical hormones. In the Q&A that follows, we talk about what “bioidentical” actually means, whether these hormones are ever justified, common misconceptions about them, and other issues.

In a special accompanying commentary, former Food and Drug Administration (FDA) Senior Medical Officer Bruce Patsner, MD, JD, also weighs in on the issue.

What is “bioidentical”?

OBG MANAGEMENT: Let’s start with the basics. What does the word “bioidentical” mean? Is it a legitimate medical term?

DR. PINKERTON: Bioidentical hormones are exogenous hormones that are biochemically similar to those produced endogenously by the body or ovaries. These include estrone, estradiol, estriol, progesterone, testosterone, dehydroepiandrosterone (DHEA), and cortisol. The FDA has approved many prescription products that contain bioidentical hormones. However, the term “bioidentical” is often used to refer to custom-compounded hormones. The major difference between the FDA-approved prescription bioidentical hormone products and custom-compounded products is that the former are regulated by the FDA and tested for purity, potency, efficacy, and safety.

Bioidenticals are not “natural” hormones, although many consumers think they are. In reality, compounded bioidentical hormones and FDA-approved bioidentical hormones all come from the same precursors. They begin as soy products or wild yam and then get converted to the different hormones in a laboratory in Germany before finding their way to the various world markets.

The claim that all bioidentical hormones are bioengineered to contain the same chemical structure as natural female sex hormones is false. As one expert noted, “the term ‘bioidentical’ has become inappropriately synonymous with ‘natural’ or ‘not synthetic’ and should be redefined to correct patient misconceptions.”²

Common misconceptions

OBG MANAGEMENT: What are some of the other false impressions you encounter among patients who ask for bioidenticals?

DR. PINKERTON: That the hormones are safer or more effective than hormone therapy, that they carry no risks, and that they are as well-monitored as FDA-approved products, to name a few. (For more, see “10 erroneous beliefs patients have about compounded hormones”).

OBG MANAGEMENT: Where do these ideas originate?

DR. PINKERTON: They are propagated by self-proclaimed experts and celebrities or by laypersons and physicians who devote the bulk of their time to promoting these hormones, usually at considerable cost to the patient.

OBG MANAGEMENT: What are the risks of compounded bioidentical hormones?

DR. PINKERTON: According to FDA guidance for industry, in the absence of data about these hormones, the risks and benefits should be assumed to be identical to those of FDA-approved hormone therapies, with the caveat that we don’t know from batch to batch what a woman is receiving. However, they are not regulated or monitored by the FDA, so we are lacking testing for purity, potency, efficacy, and safety. When the FDA did analyze compounded bioidentical hormones, a significant percentage (34%) failed one or more standard quality tests.³ In comparison, FDA-approved drugs fail analytical testing at a rate of less than 2%.³

The problems with compounded hormones

BRUCE PATSNER, MD, JD
Dr. Patsner is Research Professor of Law at the University of Houston Law Center in Houston, Tex. He served as Senior Medical Officer at the US Food and Drug Administration (FDA), where he was one of the agency’s experts on pharmacy compounding of prescription hormone drug therapy for the treatment of menopausal conditions.

The FDA has nothing against compounding pharmacies per se. Individualized preparation of a customized medication for a patient, based on a valid prescription, is an essential part of the practice of pharmacy. However, some actors in the pharmacy compounding business have taken the practice to a different level, not just in terms of the volume of business they do, but in the way compounded hormones are advertised and promoted. The courts aren’t necessarily interested in intervening in cases involving high volume alone. And when it comes to unsubstantiated claims of benefit, the FDA has found it difficult to assert jurisdiction over pharmacy compounding in general, making it hard to assert control over the advertising claims these pharmacies make on behalf of compounded drugs.

The result? The FDA has been unable to rein in claims that compounded prescription drugs are safer or better than commercially prepared medications. These drugs are probably as safe and effective as their manufactured counterparts, but there are no data to confirm this assumption.

What’s in a name?

“Bioidentical” isn’t a bona fide term. There is no definition of it in any medical dictionary; it’s just a name the industry cooked up, a catchy one at that. And when bioidenticals are advertised and promoted, the term “natural” is usually in close proximity. Most patients equate the word natural with plant-derived substances that have not been chemically altered. The fact is, many compounded prescription drugs are derived from plants—but they are also chemically altered.

Some applications are legitimate

A number of women use compounded medications because they make it possible to obtain hormone combinations that are not readily available in cream form. For example, if a patient wants testosterone as part of a cream of estrogen and progesterone, a compounded product is the only option.

Show me the data

No studies have compared compounded drugs with commercial drugs—and such studies are exceedingly unlikely. Compounding pharmacies have no incentive to conduct or participate in such studies. The pharmaceutical compounding industry is a multibillion-dollar enterprise in this country, and compounded prescription drugs for menopausal conditions are probably the biggest product outside of the oncology arena. Proponents of compounded hormones have a captive audience, so to speak, made up of women who don’t like commercial drug manufacturers or who prefer products that appear to be natural, or both.

The problem is that these women receive no package insert or prescription drug label with their hormones. Warning labels are not required because compounded drugs are not regulated by the FDA. Consumers are basically at the mercy of whatever claims they read on the Internet or in the lay literature, which tends to be written by people who have a financial interest in affiliating with the compounding industry. It’s a very frustrating situation for a lot of people.

Unintended consequences of the WHI

The Women’s Health Initiative (WHI) stirred demand for bioidentical hormones by casting the safety claims for some commercial hormone therapy products in a less than favorable light. That wasn’t the investigators’ intent, of course, and some of the findings of the WHI have since been questioned.

The goal of the WHI was to critically evaluate some of the touted health benefits of commercial hormone therapy prescription drugs, but, by questioning some of these claims, it inadvertently pushed a significant percentage of patients toward compounded prescription drugs—and we have no safety data on them.

No one knows exactly how many women were swayed, but the consensus is that they were, and no one’s been happy about that.

The main problem with the compounded hormones, as I see it, is that women who use them do not receive any written information from the compounding pharmacist about risks and benefits. Nor do they receive the black box warnings on FDA-approved estrogen therapy. I believe women need to be adequately educated about the potential risks and benefits, as well as the lack of efficacy data and quality control, if compounded products are requested. That means it’s up to the prescriber to educate the patient about the potential risks and benefits.

Rosenthal states that symptomatic menopausal women or those who fear breast cancer or heart disease can be considered a vulnerable population: “Patients do not have the background to decipher credible sources from noncredible sources.” False claims present convincing arguments for laypersons. A woman may be vulnerable to unsubstantiated claims by virtue of her symptoms and the anxiety and even depression that they can produce. Without comprehensive education, these women cannot be assumed to be adequately informed.

Let me put it in perspective. If a patient with a history of breast cancer complains about severe vaginal dryness that interferes with her sex life, I might decide to give her the smallest amount of topical estrogen that I can—for example, a dime-sized amount of estrogen to apply to her vulvar area twice a week. This amount of estrogen can’t be detected in her system with current assays. I know that some of it will be systemically absorbed, but it cannot be detected. When the patient buys that commercially prepared cream from the pharmacist, she will receive the same black box warning that comes with all systemic hormones since the WHI. However, if she goes to a compounding pharmacist with a prescription for bioidentical hormone therapy, she will not get the warning, regardless of the ingredients or dosage.

Are compounded bioidenticals ever justified?

OBG MANAGEMENT: According to the FDA, compounding of drug products is justified only when a practitioner finds that an FDA-approved drug does not meet the patient’s needs. Do you think this is ever really the case, given the availability of FDA-approved bioidentical hormone preparations?

DR. PINKERTON: In rare cases, compounding of bioidentical hormones is justified, such as when a patient cannot tolerate an FDA-approved product. The problem is that women have been especially concerned about the safety of hormone therapy since the WHI, and bioidentical hormones have been promoted as being safer than FDA-regulated preparations, despite the lack of evidence of their safety or efficacy in peer-reviewed literature. So many women request them.

In a recent commentary, Boothby and Doering call bioidentical hormone therapy “a panacea that lacks supportive evidence.” They say, “It’s our belief that pharmacists are compounding these with the best intentions, but they are ill informed regarding the lack of scientific underpinning associated with efficacy and safety.”³

OBG MANAGEMENT: Do you ever prescribe bioidentical hormones?

DR. PINKERTON: Yes, but rarely, and primarily for women who can’t tolerate FDA-approved hormones or who, after adequate information and education, refuse FDA-approved hormone therapy.

Is salivary hormone testing informative?

OBG MANAGEMENT: Many clinicians who prescribe bioidentical hormones base the dosage on salivary hormone testing. They claim that this allows them to offer individualized formulations. Is this a reliable claim?

DR. PINKERTON: No, it isn’t. Although compounded bioidentical hormone therapy is often prescribed on the basis of salivary hormone testing, there is no scientific evidence that a correlation exists between a patient’s symptoms and salivary hormones, or that salivary hormone testing reflects what is happening at the tissue level. As Fugh-Berman and Bythrow have observed, this type of testing is often used to convince asymptomatic consumers to use hormones—or symptomatic women to take higher dosages. That practice is likely to lead to adverse events.⁵ The practice also directly contradicts evidence-based guidelines, which recommend that hormone therapy be individualized on the basis of symptoms, not hormone levels.⁶

There are no published studies in the peer-reviewed literature that show that salivary testing is a reliable measure on which to safely and effectively base dosing decisions. Indeed, The Endocrine Society issued a position statement that notes, among other issues, that salivary hormone tests are “inaccurate and should not be considered reliable measures of hormones in the body.”⁷ The American College of Obstetricians and Gynecologists also advises against salivary testing, observing that:

• 1) there is no biologically meaningful relationship between salivary sex steroidal hormone concentrations and free serum hormone concentrations
• 2) there is large within-patient variability in salivary hormone concentrations. Salivary hormone levels vary depending on diet, time of day of testing, the specific hormone being tested, and other variables.³

Do bioidenticals protect against cancer?

OBG MANAGEMENT: Some reports mention the fact that many women believe that bioidentical hormones—specifically, estriol—can reduce their risk of breast and endometrial cancer. Is there any truth behind this belief?

DR. PINKERTON: Estriol is a weak estrogen. There is no evidence that, if it is given at a dosage high enough to relieve symptoms, it is any safer than estradiol.

In regard to endometrial cancer, if the exogenous estrogen—bioidentical or otherwise—is unopposed or inadequately opposed, the risk of endometrial cancer is elevated. The problem is that it is hard to determine whether estrogen is being adequately opposed, particularly when transdermal compounded progesterone is given, because the progesterone molecule is too large to be well-absorbed systemically.⁹

In regard to breast cancer, estriol is a less potent estrogen than estradiol, but it is believed to carry the same risks if it is dosed at effective levels. There is nothing about estriol per se in the peer-reviewed literature that shows that it protects against breast cancer.

The data on risk of breast cancer with estrogen therapy is confusing, with potentially higher risks if estrogen is combined with progestogen. Most of the data we have on estriol come from animals, but a study from 1980 in humans showed that, when older women with breast cancer were treated with estriol, 25% had increased growth of metastases.⁸

How do you monitor use of bioidentical hormones?

OBG MANAGEMENT: When you do prescribe a compounded bioidentical hormone, how do you monitor the patient?

DR. PINKERTON: First, I want to reiterate that I prescribe these hormones after considerable patient education about FDA-approved options and their potential risks. Second, when a patient needs or requests hormone therapy, I recommend conventional therapy. Only when she cannot tolerate or refuses FDA-approved drugs do I consider prescribing compounded bioidentical hormones—which, as I said earlier, are assumed to carry risks identical to those of FDA-approved hormones.

In some cases, I provide gynecologic care for patients who obtain compounded bioidentical hormones from other sources. What I will sometimes do, just to give myself some idea of how much estrogen they are getting, is to measure the peak and trough estradiol and estrone levels. That is, I measure the hormone level within 4 hours of the patient taking the drug to see how high it goes, and again about 12 hours later to see how low it goes. I measure both because estradiol may be peripherally converted to estrone.

Regrettably, we don’t know what to do about the various hormone levels. It isn’t like treating thyroid disorders; we normally dose estrogen therapy based on symptoms.

Who pays?

OBG MANAGEMENT: Who pays for salivary testing and compounded bioidentical hormones? Does health insurance cover them?

DR. PINKERTON: Like other “natural” products, compounded bioidenticals may cost more than their commercially prepared counterparts and often are not covered by insurance. In addition, prescribers may charge more for a “consultation” than do practitioners who accept insurance; they also may recommend salivary testing, which is expensive. Patients can end up paying large sums out of pocket.

As Rosenthal noted, many women do not appear to be concerned about the added costs.² That may be because compounded bioidentical hormone therapy is usually offered to economically advantaged patients.²

Ethical considerations

OBG MANAGEMENT: That raises an important question: What ethical considerations are inherent in the prescribing of compounded bioidenticals?

DR. PINKERTON: The fact that women who are able to pay out of pocket are the primary users of these drugs is one important point. In her analysis of the ethics surrounding bioidentical hormones, Rosenthal noted that the drugs remain “an unequal alternative, and any data collected would not be representative of the overall menopausal community.”²

A critical issue pointed out by Rosenthal is that perimenopausal and menopausal women may be particularly vulnerable to the unsubstantiated claims of purveyors of bio identical hormones. “A substantial number of women seek out bioidentical hormone replacement therapy to restore sexual well-being and functioning, in particular, who may be psychologically more vulnerable,” she writes.²

Another concern arises when the practitioner who prescribes bioidentical hormones also happens to sell them. This poses a potential conflict of interest and “violates professional ethical conduct.”²

OBG MANAGEMENT: Do physicians aggravate the problem when they accede to a patient’s request for compounded hormones?

DR. PINKERTON: Physicians and health-care providers need to stop and educate the patient about the lack of safety and efficacy data, the risks and benefits, and recognize the possibility that she has been influenced by unsubstantiated claims.

OBG Management Senior Editor Janelle Yates contributed to this article.

Hear Dr. Pinkerton discuss this article

The Women’s Health Initiative (WHI) caused a sea change in women’s attitudes toward menopausal hormone therapy and aroused many fears—not always rational—that remain almost palpable today. One study of the aftermath of the WHI found that 70% of women who were taking hormone therapy discontinued it, and 26% of women lost confidence in medical recommendations in general.¹

Into the chaos stepped Suzanne Somers, Michael Platt, and other celebrities, touting the benefits of a new kind of hormone: bioidentical. You don’t have to read Somers’ bestseller, The Sexy Years, to encounter the claims it makes on behalf of bioidenticals; the cover itself makes them clear: Discover the Hormone Connection—The Secret to Fabulous Sex, Great Health and Vitality, for Women and Men. Since publication of the book, the demand for bioidentical hormones has only increased, as women remain fearful about conventional hormone therapy.

Many ObGyns regularly field requests from patients for specially compounded bioidentical regimens. In most cases, the women who ask for these drugs are poorly informed about their risks and willing to pay out of pocket to acquire them. JoAnn V. Pinkerton, MD, sees many of these patients at The Women’s Place Midlife Health Center in Charlottesville, Virginia. OBG Management recently sat down with Dr. Pinkerton to discuss her concerns about the growing ubiquity of compounded bioidentical hormones. In the Q&A that follows, we talk about what “bioidentical” actually means, whether these hormones are ever justified, common misconceptions about them, and other issues.

In a special accompanying commentary, former Food and Drug Administration (FDA) Senior Medical Officer Bruce Patsner, MD, JD, also weighs in on the issue.

What is “bioidentical”?

OBG MANAGEMENT: Let’s start with the basics. What does the word “bioidentical” mean? Is it a legitimate medical term?

DR. PINKERTON: Bioidentical hormones are exogenous hormones that are biochemically similar to those produced endogenously by the body or ovaries. These include estrone, estradiol, estriol, progesterone, testosterone, dehydroepiandrosterone (DHEA), and cortisol. The FDA has approved many prescription products that contain bioidentical hormones. However, the term “bioidentical” is often used to refer to custom-compounded hormones. The major difference between the FDA-approved prescription bioidentical hormone products and custom-compounded products is that the former are regulated by the FDA and tested for purity, potency, efficacy, and safety.

Bioidenticals are not “natural” hormones, although many consumers think they are. In reality, compounded bioidentical hormones and FDA-approved bioidentical hormones all come from the same precursors. They begin as soy products or wild yam and then get converted to the different hormones in a laboratory in Germany before finding their way to the various world markets.

The claim that all bioidentical hormones are bioengineered to contain the same chemical structure as natural female sex hormones is false. As one expert noted, “the term ‘bioidentical’ has become inappropriately synonymous with ‘natural’ or ‘not synthetic’ and should be redefined to correct patient misconceptions.”²

Common misconceptions

OBG MANAGEMENT: What are some of the other false impressions you encounter among patients who ask for bioidenticals?

DR. PINKERTON: That the hormones are safer or more effective than hormone therapy, that they carry no risks, and that they are as well-monitored as FDA-approved products, to name a few. (For more, see “10 erroneous beliefs patients have about compounded hormones”).

OBG MANAGEMENT: Where do these ideas originate?

DR. PINKERTON: They are propagated by self-proclaimed experts and celebrities or by laypersons and physicians who devote the bulk of their time to promoting these hormones, usually at considerable cost to the patient.

OBG MANAGEMENT: What are the risks of compounded bioidentical hormones?

DR. PINKERTON: According to FDA guidance for industry, in the absence of data about these hormones, the risks and benefits should be assumed to be identical to those of FDA-approved hormone therapies, with the caveat that we don’t know from batch to batch what a woman is receiving. However, they are not regulated or monitored by the FDA, so we are lacking testing for purity, potency, efficacy, and safety. When the FDA did analyze compounded bioidentical hormones, a significant percentage (34%) failed one or more standard quality tests.³ In comparison, FDA-approved drugs fail analytical testing at a rate of less than 2%.³

The problems with compounded hormones

BRUCE PATSNER, MD, JD
Dr. Patsner is Research Professor of Law at the University of Houston Law Center in Houston, Tex. He served as Senior Medical Officer at the US Food and Drug Administration (FDA), where he was one of the agency’s experts on pharmacy compounding of prescription hormone drug therapy for the treatment of menopausal conditions.

The FDA has nothing against compounding pharmacies per se. Individualized preparation of a customized medication for a patient, based on a valid prescription, is an essential part of the practice of pharmacy. However, some actors in the pharmacy compounding business have taken the practice to a different level, not just in terms of the volume of business they do, but in the way compounded hormones are advertised and promoted. The courts aren’t necessarily interested in intervening in cases involving high volume alone. And when it comes to unsubstantiated claims of benefit, the FDA has found it difficult to assert jurisdiction over pharmacy compounding in general, making it hard to assert control over the advertising claims these pharmacies make on behalf of compounded drugs.

The result? The FDA has been unable to rein in claims that compounded prescription drugs are safer or better than commercially prepared medications. These drugs are probably as safe and effective as their manufactured counterparts, but there are no data to confirm this assumption.

What’s in a name?

“Bioidentical” isn’t a bona fide term. There is no definition of it in any medical dictionary; it’s just a name the industry cooked up, a catchy one at that. And when bioidenticals are advertised and promoted, the term “natural” is usually in close proximity. Most patients equate the word natural with plant-derived substances that have not been chemically altered. The fact is, many compounded prescription drugs are derived from plants—but they are also chemically altered.

Some applications are legitimate

A number of women use compounded medications because they make it possible to obtain hormone combinations that are not readily available in cream form. For example, if a patient wants testosterone as part of a cream of estrogen and progesterone, a compounded product is the only option.

Show me the data

No studies have compared compounded drugs with commercial drugs—and such studies are exceedingly unlikely. Compounding pharmacies have no incentive to conduct or participate in such studies. The pharmaceutical compounding industry is a multibillion-dollar enterprise in this country, and compounded prescription drugs for menopausal conditions are probably the biggest product outside of the oncology arena. Proponents of compounded hormones have a captive audience, so to speak, made up of women who don’t like commercial drug manufacturers or who prefer products that appear to be natural, or both.

The problem is that these women receive no package insert or prescription drug label with their hormones. Warning labels are not required because compounded drugs are not regulated by the FDA. Consumers are basically at the mercy of whatever claims they read on the Internet or in the lay literature, which tends to be written by people who have a financial interest in affiliating with the compounding industry. It’s a very frustrating situation for a lot of people.

Unintended consequences of the WHI

The Women’s Health Initiative (WHI) stirred demand for bioidentical hormones by casting the safety claims for some commercial hormone therapy products in a less than favorable light. That wasn’t the investigators’ intent, of course, and some of the findings of the WHI have since been questioned.

The goal of the WHI was to critically evaluate some of the touted health benefits of commercial hormone therapy prescription drugs, but, by questioning some of these claims, it inadvertently pushed a significant percentage of patients toward compounded prescription drugs—and we have no safety data on them.

No one knows exactly how many women were swayed, but the consensus is that they were, and no one’s been happy about that.

The main problem with the compounded hormones, as I see it, is that women who use them do not receive any written information from the compounding pharmacist about risks and benefits. Nor do they receive the black box warnings on FDA-approved estrogen therapy. I believe women need to be adequately educated about the potential risks and benefits, as well as the lack of efficacy data and quality control, if compounded products are requested. That means it’s up to the prescriber to educate the patient about the potential risks and benefits.

Rosenthal states that symptomatic menopausal women or those who fear breast cancer or heart disease can be considered a vulnerable population: “Patients do not have the background to decipher credible sources from noncredible sources.” False claims present convincing arguments for laypersons. A woman may be vulnerable to unsubstantiated claims by virtue of her symptoms and the anxiety and even depression that they can produce. Without comprehensive education, these women cannot be assumed to be adequately informed.

Let me put it in perspective. If a patient with a history of breast cancer complains about severe vaginal dryness that interferes with her sex life, I might decide to give her the smallest amount of topical estrogen that I can—for example, a dime-sized amount of estrogen to apply to her vulvar area twice a week. This amount of estrogen can’t be detected in her system with current assays. I know that some of it will be systemically absorbed, but it cannot be detected. When the patient buys that commercially prepared cream from the pharmacist, she will receive the same black box warning that comes with all systemic hormones since the WHI. However, if she goes to a compounding pharmacist with a prescription for bioidentical hormone therapy, she will not get the warning, regardless of the ingredients or dosage.

Are compounded bioidenticals ever justified?

OBG MANAGEMENT: According to the FDA, compounding of drug products is justified only when a practitioner finds that an FDA-approved drug does not meet the patient’s needs. Do you think this is ever really the case, given the availability of FDA-approved bioidentical hormone preparations?

DR. PINKERTON: In rare cases, compounding of bioidentical hormones is justified, such as when a patient cannot tolerate an FDA-approved product. The problem is that women have been especially concerned about the safety of hormone therapy since the WHI, and bioidentical hormones have been promoted as being safer than FDA-regulated preparations, despite the lack of evidence of their safety or efficacy in peer-reviewed literature. So many women request them.

In a recent commentary, Boothby and Doering call bioidentical hormone therapy “a panacea that lacks supportive evidence.” They say, “It’s our belief that pharmacists are compounding these with the best intentions, but they are ill informed regarding the lack of scientific underpinning associated with efficacy and safety.”³

OBG MANAGEMENT: Do you ever prescribe bioidentical hormones?

DR. PINKERTON: Yes, but rarely, and primarily for women who can’t tolerate FDA-approved hormones or who, after adequate information and education, refuse FDA-approved hormone therapy.

Is salivary hormone testing informative?

OBG MANAGEMENT: Many clinicians who prescribe bioidentical hormones base the dosage on salivary hormone testing. They claim that this allows them to offer individualized formulations. Is this a reliable claim?

DR. PINKERTON: No, it isn’t. Although compounded bioidentical hormone therapy is often prescribed on the basis of salivary hormone testing, there is no scientific evidence that a correlation exists between a patient’s symptoms and salivary hormones, or that salivary hormone testing reflects what is happening at the tissue level. As Fugh-Berman and Bythrow have observed, this type of testing is often used to convince asymptomatic consumers to use hormones—or symptomatic women to take higher dosages. That practice is likely to lead to adverse events.⁵ The practice also directly contradicts evidence-based guidelines, which recommend that hormone therapy be individualized on the basis of symptoms, not hormone levels.⁶

There are no published studies in the peer-reviewed literature that show that salivary testing is a reliable measure on which to safely and effectively base dosing decisions. Indeed, The Endocrine Society issued a position statement that notes, among other issues, that salivary hormone tests are “inaccurate and should not be considered reliable measures of hormones in the body.”⁷ The American College of Obstetricians and Gynecologists also advises against salivary testing, observing that:

• 1) there is no biologically meaningful relationship between salivary sex steroidal hormone concentrations and free serum hormone concentrations
• 2) there is large within-patient variability in salivary hormone concentrations. Salivary hormone levels vary depending on diet, time of day of testing, the specific hormone being tested, and other variables.³

Do bioidenticals protect against cancer?

OBG MANAGEMENT: Some reports mention the fact that many women believe that bioidentical hormones—specifically, estriol—can reduce their risk of breast and endometrial cancer. Is there any truth behind this belief?

DR. PINKERTON: Estriol is a weak estrogen. There is no evidence that, if it is given at a dosage high enough to relieve symptoms, it is any safer than estradiol.

In regard to endometrial cancer, if the exogenous estrogen—bioidentical or otherwise—is unopposed or inadequately opposed, the risk of endometrial cancer is elevated. The problem is that it is hard to determine whether estrogen is being adequately opposed, particularly when transdermal compounded progesterone is given, because the progesterone molecule is too large to be well-absorbed systemically.⁹

In regard to breast cancer, estriol is a less potent estrogen than estradiol, but it is believed to carry the same risks if it is dosed at effective levels. There is nothing about estriol per se in the peer-reviewed literature that shows that it protects against breast cancer.

The data on risk of breast cancer with estrogen therapy is confusing, with potentially higher risks if estrogen is combined with progestogen. Most of the data we have on estriol come from animals, but a study from 1980 in humans showed that, when older women with breast cancer were treated with estriol, 25% had increased growth of metastases.⁸

How do you monitor use of bioidentical hormones?

OBG MANAGEMENT: When you do prescribe a compounded bioidentical hormone, how do you monitor the patient?

DR. PINKERTON: First, I want to reiterate that I prescribe these hormones after considerable patient education about FDA-approved options and their potential risks. Second, when a patient needs or requests hormone therapy, I recommend conventional therapy. Only when she cannot tolerate or refuses FDA-approved drugs do I consider prescribing compounded bioidentical hormones—which, as I said earlier, are assumed to carry risks identical to those of FDA-approved hormones.

In some cases, I provide gynecologic care for patients who obtain compounded bioidentical hormones from other sources. What I will sometimes do, just to give myself some idea of how much estrogen they are getting, is to measure the peak and trough estradiol and estrone levels. That is, I measure the hormone level within 4 hours of the patient taking the drug to see how high it goes, and again about 12 hours later to see how low it goes. I measure both because estradiol may be peripherally converted to estrone.

Regrettably, we don’t know what to do about the various hormone levels. It isn’t like treating thyroid disorders; we normally dose estrogen therapy based on symptoms.

Who pays?

OBG MANAGEMENT: Who pays for salivary testing and compounded bioidentical hormones? Does health insurance cover them?

DR. PINKERTON: Like other “natural” products, compounded bioidenticals may cost more than their commercially prepared counterparts and often are not covered by insurance. In addition, prescribers may charge more for a “consultation” than do practitioners who accept insurance; they also may recommend salivary testing, which is expensive. Patients can end up paying large sums out of pocket.

As Rosenthal noted, many women do not appear to be concerned about the added costs.² That may be because compounded bioidentical hormone therapy is usually offered to economically advantaged patients.²

Ethical considerations

OBG MANAGEMENT: That raises an important question: What ethical considerations are inherent in the prescribing of compounded bioidenticals?

DR. PINKERTON: The fact that women who are able to pay out of pocket are the primary users of these drugs is one important point. In her analysis of the ethics surrounding bioidentical hormones, Rosenthal noted that the drugs remain “an unequal alternative, and any data collected would not be representative of the overall menopausal community.”²

A critical issue pointed out by Rosenthal is that perimenopausal and menopausal women may be particularly vulnerable to the unsubstantiated claims of purveyors of bio identical hormones. “A substantial number of women seek out bioidentical hormone replacement therapy to restore sexual well-being and functioning, in particular, who may be psychologically more vulnerable,” she writes.²

Another concern arises when the practitioner who prescribes bioidentical hormones also happens to sell them. This poses a potential conflict of interest and “violates professional ethical conduct.”²

OBG MANAGEMENT: Do physicians aggravate the problem when they accede to a patient’s request for compounded hormones?

DR. PINKERTON: Physicians and health-care providers need to stop and educate the patient about the lack of safety and efficacy data, the risks and benefits, and recognize the possibility that she has been influenced by unsubstantiated claims.

Population-based screening for carriers of genetic diseases and advances in neonatal and pediatric genetic testing have resulted in more and more couples identified as at-risk for inherited disorders. Increasingly, women in these couples ask their ObGyn about their options for future pregnancies.

For some women, genetic testing of a pregnancy as early as possible—even before implantation—is desirable. In vitro fertilization affords such direct access to the genetic material of either gametes before fertilization (i.e., polar-body biopsy) or blastomeres once fertilization has occurred (blastomere biopsy). Complex genetic analysis of these single cells is now possible. Because polar-body biopsy is restricted to testing for maternal disease, blastomere biopsy has gained favor as the method of choice for genetic testing of preimplantation pregnancies.

The duality of genetic testing

Regardless of what genetic material is tested, preimplantation genetic testing encompasses two distinct categories: preimplantation genetic diagnosis, or PGD, and preimplantation genetic screening, or PGS.

What is PGD?

Here, testing is confined to women at risk of an offspring with an identified genetic abnormality. These women, or their partner, typically carry a gene mutation that, alone or in combination with another mutation in the same gene, would result in an identifiable outcome in their child (for example, autosomal-recessive, autosomal-dominant, and X-linked disorders).

PGD, by definition, also includes testing of women, or their partner, who possess a balanced chromosome rearrangement (translocation, inversion). Offspring of carriers of balanced chromosome rearrangements are at increased risk of particular genetic abnormalities, as a result of unbalanced segregation of chromosomes involved in their rearrangement.

How does PGS differ from PGD?

Screening, in contrast, focuses analysis on offspring of women who are theoretically at increased risk of a genetic abnormality based on their age or reproductive history, not on their genetic makeup. PGS looks specifically for chromosomal content, and is based on the premise that decreasing the rate of aneuploidy among the conceptions of women 1) of advanced maternal age, 2) who experience habitual miscarriage, or 3) who have failed multiple cycles of in vitro fertilization (IVF) would increase the rate of implantation and, ultimately, the live birth rate.

The articles below, beginning with a committee opinion from the American Society for Reproductive Medicine (ASRM), address the following:

• evidence in support of PGD for genetic disease
  
• caution about using PGS, in its current format, for aneuploidy screening.
  

PGD can reduce the risk of a child with a specific genetic abnormality carried by one or both parents

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

A gene mutation carried by one or both parents can increase the risk that their offspring will be affected with an inherited condition. Common examples include autosomal-recessive disorders such as cystic fibrosis; autosomal-dominant disorders such as neurofibromatosis; and X-linked disorders such as hemophilia A.

Recently, human leukocyte antigens (HLA) have been assessed in conjunction with testing for specific genetic diseases, such as Fanconi anemia. In these settings, the intent is to recognize not only the blastomeres that are free of Fanconi anemia, but also those that are potential HLA matches and, therefore, potential donors for an (older) affected sibling.

PGD has been extended to women, or their partner, who possess a gene mutation that places them at increased risk of cancer (such as BRCA-1) and who wish to avoid transmitting that risk-conferring gene to their offspring.

For these diseases, and for many others, knowledge of the specific genetic mutation enables similar molecular testing to be accomplished on a single cell, such as a blastomere.

Technical concerns of testing must be part
of the physician–patient discussion

Typically, PGD analysis is initiated by polymerase chain reaction (PCR) of DNA content extracted from the single cell. This is followed by application of mutation-appropriate molecular technology. Given 1) the short time in which these PGD results are needed (often, 24 to 48 hours) and 2) the limited amount of genetic material available for analysis, technical restraints on testing are recognized:

• Extraneous DNA contamination remains a problem with molecular technology, despite application of intracytoplasmic sperm injection
  
• Only partial amplification of the allele may occur, or allele “drop-out” may be present; both of these phenomena can cause false-negative results
  
• Error can occur dually: 1) Presumably unaffected embryos that are, indeed, affected are transferred and 2) actually normal embryos that have been interpreted incorrectly as abnormal are discarded
  
• The rate of misdiagnosis (false-negative results) ranges from 2% (with autosomal-recessive disorders) to 10% (with autosomal-dominant disorders), although this rate can be lessened with the use of linked markers.
  

PGD for investigating balanced chromosome rearrangements

These rearrangements represent another type of genetic abnormality in which PGD can reduce the likelihood of a conception that carries a specific genetic abnormality.

When one parent carries a balanced chromosome translocation, fluorescence in-situ hybridization (FISH) can be applied to assess the segregation of at-risk chromosomes in a single blastomere cell. In this technique, fluorescence-labeled DNA probes, selected for specificity to the translocation in question, are applied to the single cell fixed on a glass slide. Copies of the DNA segment and, by inference, the chromosomal segment in question are assessed by quantification of the sites of positive fluorescence.

Because translocation carriers are, theoretically, at high risk of transmission of an unbalanced segregant to the blastomere, as many as 10 blastomeres will often be screened until one or two are deemed normal for the FISH probes in question. When implantation does succeed after FISH analysis for a chromosome rearrangement, however, the pregnancy loss rate is lower and the likelihood of a live birth is higher.

Again, in-depth consultation is needed before PGD

Whether PGD is planned for investigating a single-gene disorder or a chromosome translocation, detailed consultation with the woman or the couple is important. This effort should include not only genetic counseling about inheritance, the natural history of the disorder in question, and other options for avoiding the transmission of the disorder—in addition, additional time should be spent describing:

• risks associated with IVF procedures and embryo biopsy (and with extended culture, if needed)
  
• technical limitations of the particular testing that is being considered
  
• options for prenatal testing during a pregnancy
  
• the possibility that embryos suitable for transfer will not be found (and that, potentially, erroneously tested normal embryos will not be transferred)
  
• disposition of embryos in which test results are inconclusive.
  

PGS for women at increased risk of aneuploidy isn’t supported by evidence; consider it investigational

Mastenbroek S, Twisk M, van Echten-Arends J, et al. In vitro fertilization with preimplantation genetic screening. N Engl J Med. 2007;357:9–17.

Mersereau JE, Pergament E, Zhang X, Milad MP. Preimplantation genetic screening to improve in vitro fertilization pregnancy rates: a prospective randomized controlled trial. Fertil Steril. 2008;90:1287–1289.

Aneuploidy contributes to pregnancy loss among women as they become older. Theoretically, avoiding aneuploid pregnancy among embryos transferred during IVF cycles—in older women and in women experiencing multiple pregnancy losses and failed IVF cycles—was expected to increase the implantation rate and decrease the rate of pregnancy loss.

This hypothesis was supported, at first, by observational trials. But at least one randomized study, by Staessen and colleagues,¹ failed to demonstrate that PGS is beneficial in women of advanced maternal age.

Now, a large multicenter, randomized, double-blind, controlled trial conducted by Mastenbroek and co-workers provides further evidence that PGS does not increase the rate of pregnancy and, in fact, significantly reduces that rate among women of advanced maternal age.

The Mastenbroek study compared outcomes among 206 women who had PGS and 202 women who did not. Both groups were matched for maternal age older than 35 years. Blastomeres were analyzed for eight chromosomes, including those known to be highly associated with miscarriage (1, 16, 17, 13, 18, and 21; X and Y).

Among women who underwent PGS, 25% had an ongoing pregnancy of at least 12 weeks’ gestation, compared with 37% of unscreened women. A similar higher rate of live birth was seen among unscreened women (35%, versus 24% in the PGS group).

Mastenbroek’s results are comparable to what was reported from an earlier randomized trial of PGS,¹ in which the implantation rate as the primary outcome among women who had PGS and among controls was not significantly different. Contributors to 1) the lack of success of PGS and 2) the apparent detriment of PGS to the ongoing pregnancy rate include:

• potential for damage to the embryo at biopsy
  
• limitations imposed by FISH technology on the number of probes that can be accurately assessed technically
  
• a growing knowledge that a significant percentage of embryos are chromosomal mosaics at this stage—a phenomenon that likely results in nontransfer of embryos that have the potential for developing karyotypically normally.
  

Does PGS improve outcomes?

More recently, Mersereau and colleagues reported pilot results from a prospective, randomized, controlled trial that assessed whether PGS could improve pregnancy outcomes. Here, selection of infertile women for the study was not restricted to poor prognosis categories, such as advanced maternal age and recurrent pregnancy loss.

Using the live birth rate as the outcome measure, PGS for seven chromosomes was determined not to be associated with a significantly increased live birth rate among screened pregnancies. Sample sizes had been calculated to establish, with significance, a 50% increase in live births—from 30% in the control (unscreened) population to 45% in the screened population. Secondary endpoints, such as the implantation rate and pregnancy loss, also did not differ significantly between the PGS cases and controls.

Again, technical difficulties of two-blastomere biopsy, with its potential for embryo damage, and the presence of underlying embryo mosaicism represent possible barriers to improving the live birth rate when utilizing PGS.

Technical limitations may be one of the largest obstacles
to applying PGS

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

FISH probes can be chosen to reflect the nature of a given patient’s risk (advanced maternal age, recurrent pregnancy loss) when performing PGS, but the technique itself is limited by the number of probe sites that can be interpreted accurately at one time. Typically, analysis of more than five chromosomes requires two cycles of hybridization, with their associated time requirement and potential for degradation of the single cell.

Alternatively, advances in the analysis of all 23 chromosomes through comparative genomic hybridization may, ultimately, provide an avenue for applying PGS. At the moment, time limitations prohibit comparative genomic hybridization without embryo cryopreservation. Further investigation of other technical limitations, such as the high rate of mosaicism, has revealed that, when two cells are examined and found to be karyotypically discordant, further analysis of the entire embryo will reveal that more than 50% of embryos are, in fact, euploid—that is, chromosomally normal. Random biopsy of the abnormal cell solely would relegate the embryo to nontransfer, despite the predominance of an underlying euploid state.

Understanding of the potential that embryos have to self-correct early mosaicism is growing; we now know that almost one half of embryos identified as aneuploid at cleavage stage correct to euploid if they survive to blastocyst stage. A karyotypic abnormality in a single cell from a day-3 embryo does not always signal an abnormal embryo.

ASRM does not support PGS to improve the live birth rate

This determination by ASRM is based on available evidence about advanced maternal age, recurrent pregnancy loss, recurrent implantation failure, and recurrent aneuploidy loss:

• In women of advanced maternal age, many day-3 embryos display aneuploidy when studied by FISH. In theory, exclusion of these embryos for transfer should improve implantation and live birth rates, but evidence does not support that premise.
  
• Because almost 70% of spontaneous pregnancy loss is caused by a karyotypic abnormality, and women with karyotypically recurrent pregnancy loss are more likely to experience subsequent loss with karyotype abnormalities, the premise of preimplantation screening for aneuploidy also appeared to be well founded. Studies at this time are limited to retrospective series, without randomized controlled trials published.
  
• Among women who experience repeated implantation failure, a finding of more than 50% abnormal embryos isn’t uncommon, yet several studies have not supported an increased implantation rate or live birth rate after PGS.
  

A literature review of PGS calls its introduction “premature”

Gleicher N, Weghofer A, Barad D. Preimplantation genetic screening: “established” and ready for prime time? Fertil Steril. 2008;89:780–788.

After ASRM recognized PGD as an established technique in a 2001 committee opinion, extension of this status to PGS was inadvertently assumed. But PGS is a different testing modality—with different indications, risk/benefit profiles, and efficacy than PGD.

Today, FISH probes are utilized for PGS; the false-negative rate of FISH appears to be driven by the technical constraints of the technology. Potentially increasing the false-negative rate are inadequate hybridization and the use of increasing numbers of probes and hybridization cycles.

Conversely, the false-positive rate—the number of embryos not transferred that are, in fact, chromosomally normal—varies markedly from one study to another, and may be as high as 20% when discarded embryos are more completely assessed.

Similarly, laboratories utilize different methods of obtaining the genetic material. These methods range from biopsy of polar bodies to single-cell blastomere and routine two-cell blastomere biopsy—and, more recently, to blastocyst biopsy. The impact of these various embryo manipulations has yet to be fully considered. Whether biopsy affects the embryo has received little attention.

In fact, embryos that are of poor quality before biopsy—such as those found in women of advanced maternal age—may be more susceptible to the effects of biopsy. The outcome with such embryos may be of even greater detriment to the implantation rate (as discussed in regard to the Mastenbroek study earlier in this article).

The logic of performing PGS for aneuploidy in women of advanced maternal age was reasonable. But this group of women—in whom ovarian reserve is diminished, who respond poorly to ovulation induction, thereby limiting the total number of embryos for analysis and the poorer quality embryos possibly further impaired by the biopsy itself—represent the population that may be least amenable to PGS.

A further observation about PGS in women who have experienced recurrent pregnancy loss or IVF failure: Any impairment of embryos that is a consequence of the method of biopsy may further undermine the generally unsupportive results of PGS that have been documented in these patients.

Consensus on performing PGS

An assessment of European studies and practices reveals similar concerns voiced by the European Society for Human Reproduction and Embryology (ESHRE) PGD Consortium Steering Committee. The committee recently asserted a comparable opinion about “the insufficient data that demonstrate PGS is indeed a cost-effective alternative for standard IVF.”² Gleicher and colleagues, in their review of the literature, conclude that the indications for PGS are currently undefined and, as such, screening should be considered experimental.

Gleicher’s sentiments echo the recommendations of ASRM that, when PGS is considered,

• patients undergo counseling about its limitations, risk of error, and lack of evidence that it improves the live-birth rate
  
• available evidence does not support improvement in the live birth rate in women of advanced maternal age, who have failed previous implantation, who have experienced recurrent pregnancy loss, or who have experienced recurrent pregnancy loss specifically related to aneuploidy
  
• decisions about management should not be based on aneuploidy results of prior PGS cycles for a woman who has experienced recurrent implantation failure.
  

Population-based screening for carriers of genetic diseases and advances in neonatal and pediatric genetic testing have resulted in more and more couples identified as at-risk for inherited disorders. Increasingly, women in these couples ask their ObGyn about their options for future pregnancies.

For some women, genetic testing of a pregnancy as early as possible—even before implantation—is desirable. In vitro fertilization affords such direct access to the genetic material of either gametes before fertilization (i.e., polar-body biopsy) or blastomeres once fertilization has occurred (blastomere biopsy). Complex genetic analysis of these single cells is now possible. Because polar-body biopsy is restricted to testing for maternal disease, blastomere biopsy has gained favor as the method of choice for genetic testing of preimplantation pregnancies.

The duality of genetic testing

Regardless of what genetic material is tested, preimplantation genetic testing encompasses two distinct categories: preimplantation genetic diagnosis, or PGD, and preimplantation genetic screening, or PGS.

What is PGD?

Here, testing is confined to women at risk of an offspring with an identified genetic abnormality. These women, or their partner, typically carry a gene mutation that, alone or in combination with another mutation in the same gene, would result in an identifiable outcome in their child (for example, autosomal-recessive, autosomal-dominant, and X-linked disorders).

PGD, by definition, also includes testing of women, or their partner, who possess a balanced chromosome rearrangement (translocation, inversion). Offspring of carriers of balanced chromosome rearrangements are at increased risk of particular genetic abnormalities, as a result of unbalanced segregation of chromosomes involved in their rearrangement.

How does PGS differ from PGD?

Screening, in contrast, focuses analysis on offspring of women who are theoretically at increased risk of a genetic abnormality based on their age or reproductive history, not on their genetic makeup. PGS looks specifically for chromosomal content, and is based on the premise that decreasing the rate of aneuploidy among the conceptions of women 1) of advanced maternal age, 2) who experience habitual miscarriage, or 3) who have failed multiple cycles of in vitro fertilization (IVF) would increase the rate of implantation and, ultimately, the live birth rate.

The articles below, beginning with a committee opinion from the American Society for Reproductive Medicine (ASRM), address the following:

• evidence in support of PGD for genetic disease
  
• caution about using PGS, in its current format, for aneuploidy screening.
  

PGD can reduce the risk of a child with a specific genetic abnormality carried by one or both parents

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

A gene mutation carried by one or both parents can increase the risk that their offspring will be affected with an inherited condition. Common examples include autosomal-recessive disorders such as cystic fibrosis; autosomal-dominant disorders such as neurofibromatosis; and X-linked disorders such as hemophilia A.

Recently, human leukocyte antigens (HLA) have been assessed in conjunction with testing for specific genetic diseases, such as Fanconi anemia. In these settings, the intent is to recognize not only the blastomeres that are free of Fanconi anemia, but also those that are potential HLA matches and, therefore, potential donors for an (older) affected sibling.

PGD has been extended to women, or their partner, who possess a gene mutation that places them at increased risk of cancer (such as BRCA-1) and who wish to avoid transmitting that risk-conferring gene to their offspring.

For these diseases, and for many others, knowledge of the specific genetic mutation enables similar molecular testing to be accomplished on a single cell, such as a blastomere.

Technical concerns of testing must be part
of the physician–patient discussion

Typically, PGD analysis is initiated by polymerase chain reaction (PCR) of DNA content extracted from the single cell. This is followed by application of mutation-appropriate molecular technology. Given 1) the short time in which these PGD results are needed (often, 24 to 48 hours) and 2) the limited amount of genetic material available for analysis, technical restraints on testing are recognized:

• Extraneous DNA contamination remains a problem with molecular technology, despite application of intracytoplasmic sperm injection
  
• Only partial amplification of the allele may occur, or allele “drop-out” may be present; both of these phenomena can cause false-negative results
  
• Error can occur dually: 1) Presumably unaffected embryos that are, indeed, affected are transferred and 2) actually normal embryos that have been interpreted incorrectly as abnormal are discarded
  
• The rate of misdiagnosis (false-negative results) ranges from 2% (with autosomal-recessive disorders) to 10% (with autosomal-dominant disorders), although this rate can be lessened with the use of linked markers.
  

PGD for investigating balanced chromosome rearrangements

These rearrangements represent another type of genetic abnormality in which PGD can reduce the likelihood of a conception that carries a specific genetic abnormality.

When one parent carries a balanced chromosome translocation, fluorescence in-situ hybridization (FISH) can be applied to assess the segregation of at-risk chromosomes in a single blastomere cell. In this technique, fluorescence-labeled DNA probes, selected for specificity to the translocation in question, are applied to the single cell fixed on a glass slide. Copies of the DNA segment and, by inference, the chromosomal segment in question are assessed by quantification of the sites of positive fluorescence.

Because translocation carriers are, theoretically, at high risk of transmission of an unbalanced segregant to the blastomere, as many as 10 blastomeres will often be screened until one or two are deemed normal for the FISH probes in question. When implantation does succeed after FISH analysis for a chromosome rearrangement, however, the pregnancy loss rate is lower and the likelihood of a live birth is higher.

Again, in-depth consultation is needed before PGD

Whether PGD is planned for investigating a single-gene disorder or a chromosome translocation, detailed consultation with the woman or the couple is important. This effort should include not only genetic counseling about inheritance, the natural history of the disorder in question, and other options for avoiding the transmission of the disorder—in addition, additional time should be spent describing:

• risks associated with IVF procedures and embryo biopsy (and with extended culture, if needed)
  
• technical limitations of the particular testing that is being considered
  
• options for prenatal testing during a pregnancy
  
• the possibility that embryos suitable for transfer will not be found (and that, potentially, erroneously tested normal embryos will not be transferred)
  
• disposition of embryos in which test results are inconclusive.
  

PGS for women at increased risk of aneuploidy isn’t supported by evidence; consider it investigational

Mastenbroek S, Twisk M, van Echten-Arends J, et al. In vitro fertilization with preimplantation genetic screening. N Engl J Med. 2007;357:9–17.

Mersereau JE, Pergament E, Zhang X, Milad MP. Preimplantation genetic screening to improve in vitro fertilization pregnancy rates: a prospective randomized controlled trial. Fertil Steril. 2008;90:1287–1289.

Aneuploidy contributes to pregnancy loss among women as they become older. Theoretically, avoiding aneuploid pregnancy among embryos transferred during IVF cycles—in older women and in women experiencing multiple pregnancy losses and failed IVF cycles—was expected to increase the implantation rate and decrease the rate of pregnancy loss.

This hypothesis was supported, at first, by observational trials. But at least one randomized study, by Staessen and colleagues,¹ failed to demonstrate that PGS is beneficial in women of advanced maternal age.

Now, a large multicenter, randomized, double-blind, controlled trial conducted by Mastenbroek and co-workers provides further evidence that PGS does not increase the rate of pregnancy and, in fact, significantly reduces that rate among women of advanced maternal age.

The Mastenbroek study compared outcomes among 206 women who had PGS and 202 women who did not. Both groups were matched for maternal age older than 35 years. Blastomeres were analyzed for eight chromosomes, including those known to be highly associated with miscarriage (1, 16, 17, 13, 18, and 21; X and Y).

Among women who underwent PGS, 25% had an ongoing pregnancy of at least 12 weeks’ gestation, compared with 37% of unscreened women. A similar higher rate of live birth was seen among unscreened women (35%, versus 24% in the PGS group).

Mastenbroek’s results are comparable to what was reported from an earlier randomized trial of PGS,¹ in which the implantation rate as the primary outcome among women who had PGS and among controls was not significantly different. Contributors to 1) the lack of success of PGS and 2) the apparent detriment of PGS to the ongoing pregnancy rate include:

• potential for damage to the embryo at biopsy
  
• limitations imposed by FISH technology on the number of probes that can be accurately assessed technically
  
• a growing knowledge that a significant percentage of embryos are chromosomal mosaics at this stage—a phenomenon that likely results in nontransfer of embryos that have the potential for developing karyotypically normally.
  

Does PGS improve outcomes?

More recently, Mersereau and colleagues reported pilot results from a prospective, randomized, controlled trial that assessed whether PGS could improve pregnancy outcomes. Here, selection of infertile women for the study was not restricted to poor prognosis categories, such as advanced maternal age and recurrent pregnancy loss.

Using the live birth rate as the outcome measure, PGS for seven chromosomes was determined not to be associated with a significantly increased live birth rate among screened pregnancies. Sample sizes had been calculated to establish, with significance, a 50% increase in live births—from 30% in the control (unscreened) population to 45% in the screened population. Secondary endpoints, such as the implantation rate and pregnancy loss, also did not differ significantly between the PGS cases and controls.

Again, technical difficulties of two-blastomere biopsy, with its potential for embryo damage, and the presence of underlying embryo mosaicism represent possible barriers to improving the live birth rate when utilizing PGS.

Technical limitations may be one of the largest obstacles
to applying PGS

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

FISH probes can be chosen to reflect the nature of a given patient’s risk (advanced maternal age, recurrent pregnancy loss) when performing PGS, but the technique itself is limited by the number of probe sites that can be interpreted accurately at one time. Typically, analysis of more than five chromosomes requires two cycles of hybridization, with their associated time requirement and potential for degradation of the single cell.

Alternatively, advances in the analysis of all 23 chromosomes through comparative genomic hybridization may, ultimately, provide an avenue for applying PGS. At the moment, time limitations prohibit comparative genomic hybridization without embryo cryopreservation. Further investigation of other technical limitations, such as the high rate of mosaicism, has revealed that, when two cells are examined and found to be karyotypically discordant, further analysis of the entire embryo will reveal that more than 50% of embryos are, in fact, euploid—that is, chromosomally normal. Random biopsy of the abnormal cell solely would relegate the embryo to nontransfer, despite the predominance of an underlying euploid state.

Understanding of the potential that embryos have to self-correct early mosaicism is growing; we now know that almost one half of embryos identified as aneuploid at cleavage stage correct to euploid if they survive to blastocyst stage. A karyotypic abnormality in a single cell from a day-3 embryo does not always signal an abnormal embryo.

ASRM does not support PGS to improve the live birth rate

This determination by ASRM is based on available evidence about advanced maternal age, recurrent pregnancy loss, recurrent implantation failure, and recurrent aneuploidy loss:

• In women of advanced maternal age, many day-3 embryos display aneuploidy when studied by FISH. In theory, exclusion of these embryos for transfer should improve implantation and live birth rates, but evidence does not support that premise.
  
• Because almost 70% of spontaneous pregnancy loss is caused by a karyotypic abnormality, and women with karyotypically recurrent pregnancy loss are more likely to experience subsequent loss with karyotype abnormalities, the premise of preimplantation screening for aneuploidy also appeared to be well founded. Studies at this time are limited to retrospective series, without randomized controlled trials published.
  
• Among women who experience repeated implantation failure, a finding of more than 50% abnormal embryos isn’t uncommon, yet several studies have not supported an increased implantation rate or live birth rate after PGS.
  

A literature review of PGS calls its introduction “premature”

Gleicher N, Weghofer A, Barad D. Preimplantation genetic screening: “established” and ready for prime time? Fertil Steril. 2008;89:780–788.

After ASRM recognized PGD as an established technique in a 2001 committee opinion, extension of this status to PGS was inadvertently assumed. But PGS is a different testing modality—with different indications, risk/benefit profiles, and efficacy than PGD.

Today, FISH probes are utilized for PGS; the false-negative rate of FISH appears to be driven by the technical constraints of the technology. Potentially increasing the false-negative rate are inadequate hybridization and the use of increasing numbers of probes and hybridization cycles.

Conversely, the false-positive rate—the number of embryos not transferred that are, in fact, chromosomally normal—varies markedly from one study to another, and may be as high as 20% when discarded embryos are more completely assessed.

Similarly, laboratories utilize different methods of obtaining the genetic material. These methods range from biopsy of polar bodies to single-cell blastomere and routine two-cell blastomere biopsy—and, more recently, to blastocyst biopsy. The impact of these various embryo manipulations has yet to be fully considered. Whether biopsy affects the embryo has received little attention.

In fact, embryos that are of poor quality before biopsy—such as those found in women of advanced maternal age—may be more susceptible to the effects of biopsy. The outcome with such embryos may be of even greater detriment to the implantation rate (as discussed in regard to the Mastenbroek study earlier in this article).

The logic of performing PGS for aneuploidy in women of advanced maternal age was reasonable. But this group of women—in whom ovarian reserve is diminished, who respond poorly to ovulation induction, thereby limiting the total number of embryos for analysis and the poorer quality embryos possibly further impaired by the biopsy itself—represent the population that may be least amenable to PGS.

A further observation about PGS in women who have experienced recurrent pregnancy loss or IVF failure: Any impairment of embryos that is a consequence of the method of biopsy may further undermine the generally unsupportive results of PGS that have been documented in these patients.

Consensus on performing PGS

An assessment of European studies and practices reveals similar concerns voiced by the European Society for Human Reproduction and Embryology (ESHRE) PGD Consortium Steering Committee. The committee recently asserted a comparable opinion about “the insufficient data that demonstrate PGS is indeed a cost-effective alternative for standard IVF.”² Gleicher and colleagues, in their review of the literature, conclude that the indications for PGS are currently undefined and, as such, screening should be considered experimental.

Gleicher’s sentiments echo the recommendations of ASRM that, when PGS is considered,

• patients undergo counseling about its limitations, risk of error, and lack of evidence that it improves the live-birth rate
  
• available evidence does not support improvement in the live birth rate in women of advanced maternal age, who have failed previous implantation, who have experienced recurrent pregnancy loss, or who have experienced recurrent pregnancy loss specifically related to aneuploidy
  
• decisions about management should not be based on aneuploidy results of prior PGS cycles for a woman who has experienced recurrent implantation failure.
  

Population-based screening for carriers of genetic diseases and advances in neonatal and pediatric genetic testing have resulted in more and more couples identified as at-risk for inherited disorders. Increasingly, women in these couples ask their ObGyn about their options for future pregnancies.

For some women, genetic testing of a pregnancy as early as possible—even before implantation—is desirable. In vitro fertilization affords such direct access to the genetic material of either gametes before fertilization (i.e., polar-body biopsy) or blastomeres once fertilization has occurred (blastomere biopsy). Complex genetic analysis of these single cells is now possible. Because polar-body biopsy is restricted to testing for maternal disease, blastomere biopsy has gained favor as the method of choice for genetic testing of preimplantation pregnancies.

The duality of genetic testing

Regardless of what genetic material is tested, preimplantation genetic testing encompasses two distinct categories: preimplantation genetic diagnosis, or PGD, and preimplantation genetic screening, or PGS.

What is PGD?

Here, testing is confined to women at risk of an offspring with an identified genetic abnormality. These women, or their partner, typically carry a gene mutation that, alone or in combination with another mutation in the same gene, would result in an identifiable outcome in their child (for example, autosomal-recessive, autosomal-dominant, and X-linked disorders).

PGD, by definition, also includes testing of women, or their partner, who possess a balanced chromosome rearrangement (translocation, inversion). Offspring of carriers of balanced chromosome rearrangements are at increased risk of particular genetic abnormalities, as a result of unbalanced segregation of chromosomes involved in their rearrangement.

How does PGS differ from PGD?

Screening, in contrast, focuses analysis on offspring of women who are theoretically at increased risk of a genetic abnormality based on their age or reproductive history, not on their genetic makeup. PGS looks specifically for chromosomal content, and is based on the premise that decreasing the rate of aneuploidy among the conceptions of women 1) of advanced maternal age, 2) who experience habitual miscarriage, or 3) who have failed multiple cycles of in vitro fertilization (IVF) would increase the rate of implantation and, ultimately, the live birth rate.

The articles below, beginning with a committee opinion from the American Society for Reproductive Medicine (ASRM), address the following:

• evidence in support of PGD for genetic disease
  
• caution about using PGS, in its current format, for aneuploidy screening.
  

PGD can reduce the risk of a child with a specific genetic abnormality carried by one or both parents

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

A gene mutation carried by one or both parents can increase the risk that their offspring will be affected with an inherited condition. Common examples include autosomal-recessive disorders such as cystic fibrosis; autosomal-dominant disorders such as neurofibromatosis; and X-linked disorders such as hemophilia A.

Recently, human leukocyte antigens (HLA) have been assessed in conjunction with testing for specific genetic diseases, such as Fanconi anemia. In these settings, the intent is to recognize not only the blastomeres that are free of Fanconi anemia, but also those that are potential HLA matches and, therefore, potential donors for an (older) affected sibling.

PGD has been extended to women, or their partner, who possess a gene mutation that places them at increased risk of cancer (such as BRCA-1) and who wish to avoid transmitting that risk-conferring gene to their offspring.

For these diseases, and for many others, knowledge of the specific genetic mutation enables similar molecular testing to be accomplished on a single cell, such as a blastomere.

Technical concerns of testing must be part
of the physician–patient discussion

Typically, PGD analysis is initiated by polymerase chain reaction (PCR) of DNA content extracted from the single cell. This is followed by application of mutation-appropriate molecular technology. Given 1) the short time in which these PGD results are needed (often, 24 to 48 hours) and 2) the limited amount of genetic material available for analysis, technical restraints on testing are recognized:

• Extraneous DNA contamination remains a problem with molecular technology, despite application of intracytoplasmic sperm injection
  
• Only partial amplification of the allele may occur, or allele “drop-out” may be present; both of these phenomena can cause false-negative results
  
• Error can occur dually: 1) Presumably unaffected embryos that are, indeed, affected are transferred and 2) actually normal embryos that have been interpreted incorrectly as abnormal are discarded
  
• The rate of misdiagnosis (false-negative results) ranges from 2% (with autosomal-recessive disorders) to 10% (with autosomal-dominant disorders), although this rate can be lessened with the use of linked markers.
  

PGD for investigating balanced chromosome rearrangements

These rearrangements represent another type of genetic abnormality in which PGD can reduce the likelihood of a conception that carries a specific genetic abnormality.

When one parent carries a balanced chromosome translocation, fluorescence in-situ hybridization (FISH) can be applied to assess the segregation of at-risk chromosomes in a single blastomere cell. In this technique, fluorescence-labeled DNA probes, selected for specificity to the translocation in question, are applied to the single cell fixed on a glass slide. Copies of the DNA segment and, by inference, the chromosomal segment in question are assessed by quantification of the sites of positive fluorescence.

Because translocation carriers are, theoretically, at high risk of transmission of an unbalanced segregant to the blastomere, as many as 10 blastomeres will often be screened until one or two are deemed normal for the FISH probes in question. When implantation does succeed after FISH analysis for a chromosome rearrangement, however, the pregnancy loss rate is lower and the likelihood of a live birth is higher.

Again, in-depth consultation is needed before PGD

Whether PGD is planned for investigating a single-gene disorder or a chromosome translocation, detailed consultation with the woman or the couple is important. This effort should include not only genetic counseling about inheritance, the natural history of the disorder in question, and other options for avoiding the transmission of the disorder—in addition, additional time should be spent describing:

• risks associated with IVF procedures and embryo biopsy (and with extended culture, if needed)
  
• technical limitations of the particular testing that is being considered
  
• options for prenatal testing during a pregnancy
  
• the possibility that embryos suitable for transfer will not be found (and that, potentially, erroneously tested normal embryos will not be transferred)
  
• disposition of embryos in which test results are inconclusive.
  

PGS for women at increased risk of aneuploidy isn’t supported by evidence; consider it investigational

Mastenbroek S, Twisk M, van Echten-Arends J, et al. In vitro fertilization with preimplantation genetic screening. N Engl J Med. 2007;357:9–17.

Mersereau JE, Pergament E, Zhang X, Milad MP. Preimplantation genetic screening to improve in vitro fertilization pregnancy rates: a prospective randomized controlled trial. Fertil Steril. 2008;90:1287–1289.

Aneuploidy contributes to pregnancy loss among women as they become older. Theoretically, avoiding aneuploid pregnancy among embryos transferred during IVF cycles—in older women and in women experiencing multiple pregnancy losses and failed IVF cycles—was expected to increase the implantation rate and decrease the rate of pregnancy loss.

This hypothesis was supported, at first, by observational trials. But at least one randomized study, by Staessen and colleagues,¹ failed to demonstrate that PGS is beneficial in women of advanced maternal age.

Now, a large multicenter, randomized, double-blind, controlled trial conducted by Mastenbroek and co-workers provides further evidence that PGS does not increase the rate of pregnancy and, in fact, significantly reduces that rate among women of advanced maternal age.

The Mastenbroek study compared outcomes among 206 women who had PGS and 202 women who did not. Both groups were matched for maternal age older than 35 years. Blastomeres were analyzed for eight chromosomes, including those known to be highly associated with miscarriage (1, 16, 17, 13, 18, and 21; X and Y).

Among women who underwent PGS, 25% had an ongoing pregnancy of at least 12 weeks’ gestation, compared with 37% of unscreened women. A similar higher rate of live birth was seen among unscreened women (35%, versus 24% in the PGS group).

Mastenbroek’s results are comparable to what was reported from an earlier randomized trial of PGS,¹ in which the implantation rate as the primary outcome among women who had PGS and among controls was not significantly different. Contributors to 1) the lack of success of PGS and 2) the apparent detriment of PGS to the ongoing pregnancy rate include:

• potential for damage to the embryo at biopsy
  
• limitations imposed by FISH technology on the number of probes that can be accurately assessed technically
  
• a growing knowledge that a significant percentage of embryos are chromosomal mosaics at this stage—a phenomenon that likely results in nontransfer of embryos that have the potential for developing karyotypically normally.
  

Does PGS improve outcomes?

More recently, Mersereau and colleagues reported pilot results from a prospective, randomized, controlled trial that assessed whether PGS could improve pregnancy outcomes. Here, selection of infertile women for the study was not restricted to poor prognosis categories, such as advanced maternal age and recurrent pregnancy loss.

Using the live birth rate as the outcome measure, PGS for seven chromosomes was determined not to be associated with a significantly increased live birth rate among screened pregnancies. Sample sizes had been calculated to establish, with significance, a 50% increase in live births—from 30% in the control (unscreened) population to 45% in the screened population. Secondary endpoints, such as the implantation rate and pregnancy loss, also did not differ significantly between the PGS cases and controls.

Again, technical difficulties of two-blastomere biopsy, with its potential for embryo damage, and the presence of underlying embryo mosaicism represent possible barriers to improving the live birth rate when utilizing PGS.

Technical limitations may be one of the largest obstacles
to applying PGS

Practice Committee of the Society for Assisted Reproductive Technology; Practice Committee of the American Society for Reproductive Medicine. Preimplantation genetic testing: a Practice Committee opinion. Fertil Steril. 2007;88:1497–1504.

FISH probes can be chosen to reflect the nature of a given patient’s risk (advanced maternal age, recurrent pregnancy loss) when performing PGS, but the technique itself is limited by the number of probe sites that can be interpreted accurately at one time. Typically, analysis of more than five chromosomes requires two cycles of hybridization, with their associated time requirement and potential for degradation of the single cell.

Alternatively, advances in the analysis of all 23 chromosomes through comparative genomic hybridization may, ultimately, provide an avenue for applying PGS. At the moment, time limitations prohibit comparative genomic hybridization without embryo cryopreservation. Further investigation of other technical limitations, such as the high rate of mosaicism, has revealed that, when two cells are examined and found to be karyotypically discordant, further analysis of the entire embryo will reveal that more than 50% of embryos are, in fact, euploid—that is, chromosomally normal. Random biopsy of the abnormal cell solely would relegate the embryo to nontransfer, despite the predominance of an underlying euploid state.

Understanding of the potential that embryos have to self-correct early mosaicism is growing; we now know that almost one half of embryos identified as aneuploid at cleavage stage correct to euploid if they survive to blastocyst stage. A karyotypic abnormality in a single cell from a day-3 embryo does not always signal an abnormal embryo.

ASRM does not support PGS to improve the live birth rate

This determination by ASRM is based on available evidence about advanced maternal age, recurrent pregnancy loss, recurrent implantation failure, and recurrent aneuploidy loss:

• In women of advanced maternal age, many day-3 embryos display aneuploidy when studied by FISH. In theory, exclusion of these embryos for transfer should improve implantation and live birth rates, but evidence does not support that premise.
  
• Because almost 70% of spontaneous pregnancy loss is caused by a karyotypic abnormality, and women with karyotypically recurrent pregnancy loss are more likely to experience subsequent loss with karyotype abnormalities, the premise of preimplantation screening for aneuploidy also appeared to be well founded. Studies at this time are limited to retrospective series, without randomized controlled trials published.
  
• Among women who experience repeated implantation failure, a finding of more than 50% abnormal embryos isn’t uncommon, yet several studies have not supported an increased implantation rate or live birth rate after PGS.
  

A literature review of PGS calls its introduction “premature”

Gleicher N, Weghofer A, Barad D. Preimplantation genetic screening: “established” and ready for prime time? Fertil Steril. 2008;89:780–788.

After ASRM recognized PGD as an established technique in a 2001 committee opinion, extension of this status to PGS was inadvertently assumed. But PGS is a different testing modality—with different indications, risk/benefit profiles, and efficacy than PGD.

Today, FISH probes are utilized for PGS; the false-negative rate of FISH appears to be driven by the technical constraints of the technology. Potentially increasing the false-negative rate are inadequate hybridization and the use of increasing numbers of probes and hybridization cycles.

Conversely, the false-positive rate—the number of embryos not transferred that are, in fact, chromosomally normal—varies markedly from one study to another, and may be as high as 20% when discarded embryos are more completely assessed.

Similarly, laboratories utilize different methods of obtaining the genetic material. These methods range from biopsy of polar bodies to single-cell blastomere and routine two-cell blastomere biopsy—and, more recently, to blastocyst biopsy. The impact of these various embryo manipulations has yet to be fully considered. Whether biopsy affects the embryo has received little attention.

In fact, embryos that are of poor quality before biopsy—such as those found in women of advanced maternal age—may be more susceptible to the effects of biopsy. The outcome with such embryos may be of even greater detriment to the implantation rate (as discussed in regard to the Mastenbroek study earlier in this article).

The logic of performing PGS for aneuploidy in women of advanced maternal age was reasonable. But this group of women—in whom ovarian reserve is diminished, who respond poorly to ovulation induction, thereby limiting the total number of embryos for analysis and the poorer quality embryos possibly further impaired by the biopsy itself—represent the population that may be least amenable to PGS.

A further observation about PGS in women who have experienced recurrent pregnancy loss or IVF failure: Any impairment of embryos that is a consequence of the method of biopsy may further undermine the generally unsupportive results of PGS that have been documented in these patients.

Consensus on performing PGS

An assessment of European studies and practices reveals similar concerns voiced by the European Society for Human Reproduction and Embryology (ESHRE) PGD Consortium Steering Committee. The committee recently asserted a comparable opinion about “the insufficient data that demonstrate PGS is indeed a cost-effective alternative for standard IVF.”² Gleicher and colleagues, in their review of the literature, conclude that the indications for PGS are currently undefined and, as such, screening should be considered experimental.

Gleicher’s sentiments echo the recommendations of ASRM that, when PGS is considered,

• patients undergo counseling about its limitations, risk of error, and lack of evidence that it improves the live-birth rate
  
• available evidence does not support improvement in the live birth rate in women of advanced maternal age, who have failed previous implantation, who have experienced recurrent pregnancy loss, or who have experienced recurrent pregnancy loss specifically related to aneuploidy
  
• decisions about management should not be based on aneuploidy results of prior PGS cycles for a woman who has experienced recurrent implantation failure.