MS. DIANE REHMThanks for joining us. I'm Diane Rehm. When a pregnant woman visits the doctor's office today, she's presented with a menu of prenatal tests. Because the technology is changing so rapidly, what these tests reveal and what to do with the information can be confusing for both pregnant women and at times, their doctors. Here to talk about how to navigate the changing landscape of prenatal testing, Dr. Barbara Levy of The American College of Obstetricians and Gynecologists, and Lisa Freese of the George Washington University Medical Faculty Associates.

MS. DIANE REHMJoining us from Boston, Dr. Michael Greene of Massachusetts General Hospital and the Harvard Medical School. Of course, you are always part of the program. Give us a call with your questions and comments, join us at 800-433-8850. Send an email to drshow@wamu.org. Follow us on Facebook or Twitter. And thanks to all of you for being with us.

MS. LISA FREESEThank you so much, Diane.

DR. BARBARA LEVYThank you.

DR. MICHAEL GREENEThank you for inviting me.

REHMDr. Greene, I'll start with you. Explain to us a bit about how prenatal testing has evolved over the years.

GREENEYes, my goodness, it's changed quite a bit.

REHMYes.

GREENEIn the earliest days, if you will, it was a rather crude ultrasound images that were largely not good for much, except measuring the head and the long bones of the fetus to try to estimate how old it was. As ultrasound improved, we realized that we could recognize certain kinds of congenital abnormalities. And then, the next evolution was the recognition that a substance called alpha feta protein, which is produced in the fetal blood stream, gets across the placenta into the maternal blood stream in minute quantities, but we could measure that.

GREENEAnd by measuring that and finding high levels, it gave us a hint that the fetus might have a congenital abnormality, particularly of the brain or spinal cord, other congenital abnormalities were also recognized to be associated with it and subsequently it was recognized that low levels happen to be associated with certain kinds of chromosomal abnormalities, like Down Syndrome.

GREENEAnd once that -- those sentinel observations had been met, we were sort of off to the races on finding substances in the maternal blood that could give us a clue as to the health of the fetus. So that's how it started. And the most recent evolution is the recognition that tiny quantities of fetal DNA are circulating in the mother's blood and that these can be analyzed and studied in a variety of ways to assess an ever increasing number of genetic and chromosomal abnormalities in fetuses.

REHMThat really is quite a range. Dr. Barbara Levy, talk about that cell-free DNA testing that goes on. I gather they've really sort of exploded onto the market.

LEVYWell, they have. Technology, in general, as Dr. Greene has said, has really exploded large through medicine and the cell-free DNA is being widely marketed both to physicians and to women and couples who are pregnant. The problem really is the search for perfection. We are looking to find smaller and smaller pieces of evidence for things that we would like to know about and the reality is many of those things are exquisitely rare.

LEVYWe can find them. Sometimes we find things and we have no idea what they mean. And that's the downside to this incredible technology. And I don't want to take away from the technology. It's really remarkable. But so often, technology advances onto the market before we're clear about where it fits.

REHMTell me about the cell-free DNA and what it can or may tell us about the health or the viability of the fetus.

LEVYWell, it's not really designed to tell us about the viability, in other words, the health of the pregnancy. It's really designed to talk about the genetics. So what are the genes? What are the DNA elements that we can distinguish that are the baby's versus the mom's. And because our technology is so advanced, these are being marketed as 99.9 percent sensitive, for example, to pick up things like Down Syndrome.

REHMAnd how early a stage of the fetus?

LEVYGenerally, it's about 10 to 13 weeks from the first day of the last menstrual period. The pregnancy has to be far enough along for there to be adequate field DNA in the maternal circulation to pick this up.

REHMAnd Dr. Greene, what are the differences with these kinds of tests versus, say, other genetic tests like amniocenteses?

GREENESo the most important thing to distinguish, I think, here is the difference between a diagnostic test and a screening test. So an amniocenteses is a diagnostic test. In that situation, we insert a needle through the mother's skin into the fluid around the fetus. We can find fetal cells in the amniotic fluid. We can grow them in tissue culture in the laboratory and we can study the chromosomes directly.

GREENEWe can also study looking for individual genes on those chromosomes, if there's something specific that we're looking for. The difference between that diagnostic test, which requires that we put a needle into the amniotic sac, is that it exposes the fetus to a small but real risk of miscarriage from doing the diagnostic test. The important thing about the screening test of noninvasive prenatal screening using fetal DNA in the maternal circulation, is it's a simple blood test from the mother.

GREENEWe take a couple of tablespoons of blood from the mother. It's essentially no risk to pregnancy or the mother. So unfortunately, it does not have the precision that an amniocenteses does and one of the most important things that everyone employing this technology, both doctor and patient, needs to remember is that if the test is abnormal from the screening test, then you need a diagnostic test before any irrevocable actions are taken regarding the pregnancy.

REHMAnd Lisa Freese, as a genetic counselor there at George Washington University, how do you advise a young woman as she's coming in perhaps for her first, second, third visit to think about these various kinds of tests?

FREESEIt's a question of interpreting the medical information and trying to translate that into words that the patient can understand, trying to get them to come to realization about what's appropriate, but we often are fighting against bias or information they've gotten from marketing or from other either physicians or relatives or friends or blogs as to what can be provided.

REHMGive me an example.

FREESEAs we're all aware, the internet is a wonderful source, but it is personal experiences, which can sway someone's understanding of what can be provided. And as Dr. Greene said, there are differences between a diagnostic test and a screen and if they have gotten the impression that the screen will provide more than it will, we're working against that. We're trying to educate, but we have to unlearn them first and tell them what is realistic, what we can provide.

FREESEAnd we try to present them with options that are appropriate, given what technology can do, what their risk may be for before they came in, but ultimately we're trying to get them to come to that decision of what's appropriate for them.

REHMAnd Dr. Greene, Dr. Levy said earlier that some of these tests claim to be 99 percent accurate. Would you go that far?

GREENEWell, the part of the issue here is that when we use these tests, we don't speak about, quote, "accuracy." We break it down a little bit more specifically so that we say that the positive, we talk about what's called the positive and the negative predictive value of the test. And those are different things. So the positive predictive value is that if the test says that you have a problem, what's the probability that you really have a problem?

GREENEAnd the other flipside of that is, you know, the negative predictive value is that if the test says everything is fine, what's the probability that everything truly really is fine? So that we don't talk about -- usually, we don't talk about accuracy in the aggregate that way. We usually break it down according to the positive and negative predictive value because they have different meanings for our patients in a very practical way.

REHMBut I gather, Dr. Levy, the false positive rate can be pretty high?

LEVYSo it can be, yes. If we're thinking about 4 million pregnancies a year in the United States and even if a test -- and this is really the marketing hype. These are the marketing folks going out there and saying it's 99.9 percent. Well, .01 percent times 4 million births is 40,000 people with a potentially false result.

REHMDr. Barbary Levy, she's vice president of The American College of Obstetricians and Gynecologists. Short break. We'll be right back.

REHMAnd in this hour we're talking about a great new variety of prenatal testing that is being done on pregnant women. The variety can offer great choice, it can offer great comfort to some, but it can also create a great amount of anxiety. Dr. Levy, you were talking about the false positives, the false negatives. What happens if a young woman or a woman of any age who's pregnant has one of these tests, and it does come back indicating something is wrong with the fetus? What happens then?

LEVYSo as Dr. Greene suggested earlier, we go from screening now to diagnostic testing. And depending on the test, we would recommend, perhaps, an amniocentesis or another invasive test called chorionic villus sampling. Depending on where we are in the pregnancy, we might choose to recommend very highly sensitive ultrasound tests, but we would proceed to a diagnostic test. So we don't use the results of the screening to drive any intervention in the pregnancy at all, other than to get more and more accurate information.

REHMNow Lisa, where do you come in?

FREESEWe often will see patients prior to doing any screening or testing so that we can introduce all of the options because it's not the same steps that your friend took or your mother took in order to get information, and knowing what's available and working through the steps that they can take is very important so that they're making an informed decision.

REHMWould you agree with Dr. Levy that too many of these companies are hyping the accuracy and the importance of the kind of testing they provide?

FREESEI think that there has been a little bit of subsiding of the marketing and generation of advertising. I think, though still, it is going to play on the advances of the screening without talking about those negative effects that can have on either that patient's anxiety concerns, and it doesn't talk necessarily about what other options would be available should the screening come back with an abnormal result.

REHMAnd Dr. Greene, what if someone tests negative? What do you do then? And suppose it turns out that that's a false negative?

GREENESo the question here is sometimes what do you mean by negative. So in other words, most women who come to my office say to me, what can you do to tell me my baby is normal. They don't ask me what can you do to tell me my baby doesn't have a defect of the brain or doesn't have a defect of the heart. They tell me, can you tell me that my -- they ask me, can you tell me that my baby's normal.

GREENEAnd so once they've asked that question, then I need to reframe it for them a little bit so that I know exactly what kinds of -- or they know exactly what kinds of abnormalities we can detect and we cannot detect with the various diagnostic or screening options that are available to them.

REHMSo how well do you think that doctors in general are articulating these things to their patients?

GREENEWell, that's a good question, and it's hard to answer because, you know, obviously I'm just one doctor, and I don't sit in every doctor's office. And it's also difficult for doctors in various settings, rural settings especially, who don't have access to genetics counselors necessarily, to spend the time and to in fact, in fairness, have the knowledge to sit down with the patient and explain in great detail exactly what each one of these tests can and cannot detect.

REHMAll right. I want to make sure that our listeners know we are taking your calls, 800-433-8850. Send your email to drshow@wamu.org. Jose says, on Facebook, it's a money scam. Moms are made to feel it's imperative to get all these tests and maybe even made to feel guilty if they don't test for every little possibility. Where money is involved, the sky is the limit. Dr. Levy?

LEVYWell, I certainly think there's a risk there that women and their families get sucked in to thinking that more is better and that we can test for everything. And as Dr. Greene pointed out, it's very hard to sit with a couple and say I actually can't tell you that your child is going to be normal. Your risk is very, very low of having a problem, and here are the options that you have.

LEVYWe live in a culture where our society believes that more testing is always better, and that's true for cancer screening, it's true for this kind of screening. I think it's a terrible disservice to the public to make people think that we can test for everything or that it's the right thing to do to test for many, many things.

REHMAll right, I'm going to open the phones. We'll try to take as many of your calls as we can, 800-433-8850. First to Elizabeth in Alexandria, Virginia. You're on the air.

ELIZABETHHi Diane, thanks for taking my call.

REHMSure.

ELIZABETHYeah, golly, I have such a long story, and I don't want it to be long, but it is. I'm not exactly a young woman. I got married at 31, and we tried for nine years to have our son, who we finally had with IVF. And he was a beautiful, healthy little boy. But we wanted other children, and we got pregnant out of the clear blue sky, which we were so excited about, last summer, but I knew that I was not a low-risk candidate. I was already in my 40s and mid-40s, and my husband and I actually met working with people who had developmental disabilities. So we knew the range of the things that we could encounter, at least some of them.

ELIZABETHBut we went in with a high regard for people that maybe weren't genetically normal, so to speak, and I kind of let my doctor off the hook right up front. You know, he started to tell me all the tests that were available, and I said look, I know that I'm high-risk, I know that I'm the prime candidate for all these tests, but I really, I don't want to go through this pregnancy with that anxiety, and I'm not going to terminate, and I'd just as soon not really know.

ELIZABETHAnd he was actually really wonderful about it. He didn't press me, and he respected that. But then at 18 weeks, you know, we were having routine ultrasounds because those are helpful just for a lot of things related to carrying the pregnancy and knowing how far along you are and if you're having a boy or girl. And with my son, I'd had a son previous, so we had ultrasounds constantly.

REHMSure, right.

ELIZABETHSo we weren't averse to having ultrasounds, but at the 18-week ultrasound, the doc who was doing that was different than our OB, and he definitely found that things were not looking good. They were not looking normal at all. And it was really -- it was a really hard conversation, and he said that we had an array of anatomical abnormalities that probably indicated a genetic trisomy.

ELIZABETHAnd Down syndrome is actually a trisomy, it's trisomy-21, but there are other trisomies that people don't commonly know about, trisomy-13 and -18 are both lethal. And you don't end up with a child that has disabilities. You end up with a child that, what they say, you know, has an incompatibility with life, like he or she is just not going to be able to survive outside the womb. So that doctor immediately suggested that we terminate the pregnancy.

ELIZABETHAnd, you know, we decided -- we decided that we wanted to leave room for two things. We wanted to leave room for an error, that maybe there was some mistake, even though we didn't think there probably was a mistake, and we wanted to leave room for miracles, which we believe in. We don't expect, but we believe they can happen. And so we carried our little girl the remaining 20-something weeks. We carried her to 36 weeks.

ELIZABETHAnd our doc was really awesome and really supportive and basically gave us, like perinatal hospice care because we knew we were going to lose her, but we wanted to enjoy the time we had with her.

REHMI understand.

ELIZABETHSo we delivered her early, just so that her heart wouldn't give out because trisomy-13 is characterized by heart defects, brain defects, a lot of...

REHMYes, we're, yes...

ELIZABETHA big array of defects. And so he was afraid if we went the full 40 weeks that she might die in utero, and that would be a bad thing. So at 36 weeks, when she was still doing okay, we delivered her, and we got to hold her and kiss her, and our son got to meet her, and she was baptized and stuff. And I guess I just want to say we have no regrets at all that we carried her, and so if people feel like the responsible, best thing to do is to get all the diagnostics and to end the pregnancy, and they feel like they sort of have to do it, you actually can go the distance and carry the baby, and it's not the end of the world.

ELIZABETHIt's really sad, but then you don't have any of the, gosh, what if this, what if that, what if we'd have done this, and what if we'd...

REHMYes, I thank you so much for your call. I'm sorry, so sorry for your loss. And I know that what you experienced will stay with you for a lifetime. And Elizabeth mentioned trisomy with various numbers. Dr. Levy, can you explain?

LEVYSure, so we're supposed to have a certain number of chromosomes. That's how we are designed. And sometimes with an accident of nature, we create a fetus that has an extra chromosome, and that's called a trisomy. Instead of a matched pair, one from mom and one from dad, there's an extra one, and that extra one creates certain syndromes that we're aware of that we can often predict based on what we see on an ultrasound.

REHMI see.

LEVYThere are anatomic abnormalities that go along with that.

REHMAnd Dr. Greene, what about the different numbers, trisomy-13, trisomy-21? What does all that mean?

GREENESo all of the human chromosomes are numbered just for ease of reference, and so trisomy-21 means an extra number 21 chromosome, 18 and 13 respectively. The most common living trisomy that can go to term or near term is Down syndrome, which is trisomy 21. The other two chromosomal abnormalities mentioned by the caller, trisomy-18 and trisomy-13, are less frequent than Down syndrome in that order so that 18 is less common than 21, and 13 is the rarest of the three.

REHMNow we've been talking about the variety of testing and the availability thereof. How frequently are people using these various tests? Is every woman, even if she's young or as our caller, a little on the older side, is everyone being advised to use these tests, Dr. Levy?

LEVYNo. We recommend, the college recommends, that every woman be given the education, be given the option and to know what her choices are early in her pregnancy, and we hope that that can help to frame for her what her individual risk looks like. So the caller was over 40 years of age, and we've known for a very long time that chromosomal abnormalities increase with increasing maternal age.

LEVYAnd so the risk for someone like the caller is going to be substantially higher than the risk for someone who's 20 years old or 22 years old, and our job as obstetricians is to frame that risk and help a patient understand what options she has and what choices make good sense for her.

REHMNow Dr. Greene, what percentage would you say of your own patients in the 20- to 30-year-old range, what percentage of those would you recommend these kinds of testings?

GREENEWell, I'm glad you asked that question that way because the truth of the matter is that we don't recommend or advise the patients to have any testing. What we do is we make it clear to the patient what's available to them and what the testing can and can't do for them. So we don't advise or recommend that people have testing pretty much at any age, but we do advise them, or we make them aware, we offer them testing basically regardless of their age.

GREENEAs Dr. Levy pointed out, the risk of a trisomy or an aneuploidy increases with advancing maternal age, and therefore it may be more important, if you will, for older women who are interested in learning about these things to avail themselves of the testing than for younger women. But we don't advise people or recommend it. We make it -- we make them aware of what's available and what the testing can and can't do, and we give them some idea of, you know, where the landmines may be in the testing process so that they're aware of that before they go in, also.

REHMAnd here's a message on Facebook that says, I have mixed feelings about prenatal testing. Being 35, I received extra ultrasounds, and at 25 weeks, they found two markers for trisomy-18, which turned out to be incorrect at birth but caused a lot of stress throughout the pregnancy. All the extra ultrasounds missed my son's tachycardia that required a two-week NICU stay and a year of monitoring and medication. Technology saved my son in one regard but incorrectly stressed us out in another. Lisa, can you comment?

FREESEWe certainly hope that we can emphasize the side of things being normal, even in cases where there are markers seen on ultrasound that may establish an increased risk. And often those increased risks are one or two percent. So we do try to emphasize that we may be dealing, in the majority of cases, with a high likelihood, 98 or 99 percent, that everything will be well. So the step that was taken of getting definitive answers is a little bit lost there.

REHMLisa Freese, she's a senior genetic counselor at the George Washington University Medical Faculty Associates. Short break, more of your calls when we come back. Stay with us.

REHMAnd we'll go right back to the phones, 800-433-8850, to Emily in Baton Rouge, Louisiana. You're on the air.

EMILYThank you, Diane, for taking my call.

REHMSurely.

EMILYI am only 28 and pregnant but have already received news in an ultrasound that we have a few markers for Down syndrome in our child, and so I'm waiting for the results of the blood test that examines fetal DNA in the mother's blood. I'm still confused, even after talking to my doctor and reading lots of articles, why there is a difference in the accuracy between the fetal DNA blood test and the amniocentesis when both are looking at the fetus DNA directly.

REHMDr. Greene?

GREENEVery good question. The answer is that when we do an amniocentesis, we get fetal cells, and each of those fetal cells contains a full complement of chromosomes, and we can literally, on a microscope slide, spread out those chromosomes, look at them and count them. When we are doing prenatal screening using maternal blood, what we're looking for is tiny, tiny little fragments of DNA that come from all 46 chromosomes. There's only 10 percent of all the DNA in the maternal circulation that has come from the fetus.

GREENESo we've got to unscramble and sort out all of those tiny fragments. Literally hundreds of millions of fragments of studied for each prenatal screening blood test. So it is a massive computational effort to figure out which chromosomes, if any, are over-represented in the maternal circulation as compared to the way they should be. So it's a huge difference between looking at tiny, tiny little fragments, hundreds of millions of them, in the maternal circulation, as opposed to being able to look at literally 46 individual chromosomes in a single cell from a fetus.

REHMDr. Levy, do you want to add to that?

LEVYAbsolutely right. I mean, to understand the technology behind doing cell-free DNA is to understand how remarkable computational analysis has come over the last just decade. But the accuracy is really in testing the fetus directly, and when we get fragments of DNA from the maternal circulation, it's a lot of computation to get those results.

REHMEmily, does that help?

EMILYYes, very much, thank you.

REHMAll right, thanks for calling. And to Orange City, Florida. Samantha, you're on the air.

SAMANTHAGood morning. I was 26 at my first pregnancy and with my husband having a mentally handicapped brother and my father have a mentally -- Down syndrome brother, it was recommended for me to do genetic counseling. And the recommendation, from what I recall, this is 30 years ago, It seemed to me that between my husband and I, it was kind of a no-brainer with the results that we got that we should have an amniocentesis.

SAMANTHAAnd I, first listening to the program this morning, got so emotional. It's been 30 years ago, but I had a bad experience. I waited in the reception area of where I was going to get my test done, and I was informed to drink a lot of fluids. You know, I don't know why that was, but I did exactly all the instructions as I was told to do, but I was in a lot of pain because they didn't take me very soon.

SAMANTHAAnd so I carried that fluid very, very long, and it was very uncomfortable. But when I started getting tested, they put the needle in, which was surprisingly large, it was, like, shockingly large, and it hurt. That was -- didn't work, and they had to pull it out and re-insert somewhere else. They're looking on a screen and trying to determine where to put the needle in, and the screen, this was 1984, so this is quite a long time ago, it seemed like there wasn't a lot of accuracy with that.

SAMANTHAAnd they pulled it out and had to go it again, which was very uncomfortable, and I did worry. As they were trying to pull fluid in on the first injection, nothing was pulling in. So that was the drama of that. Well, what did you hit that nothing's pulling in? And he went in again, and I guess it was successful, and I went forth with the pregnancy, and everything turned out fine.

REHMGood.

SAMANTHABut with the holding of that liquid so long, I did damage my bladder, and I'm sure that sometimes these testing places do get kind of busy.

REHMWhat do you think, Dr. Levy? Was that a rare occurrence, or are the amniocentesis given sometimes by technicians as opposed to physicians?

LEVYNot to my knowledge. I think physicians overwhelmingly are the ones who perform the amniocentesis, but as Dr. Greene had said early on in the program, the ultrasound capabilities that we had in 1984 were remarkably different than what we can do in 2015. And it looked like a snowstorm on the screen. It was very difficult to distinguish things. So I feel awful for the caller's experience.

REHMI should say.

LEVYAnd it really honestly drives our hope to be able to do screening in a different way, that we reserve amniocentesis and chorionic villus sampling, the invasive tests, for diagnosis, for a diagnostic test, not a screening test, for these very reasons.

REHMBut how often do you think you go from screening to diagnosis?

LEVYWell, any time we have an abnormal screen, then we need to proceed with something more diagnostic. That doesn't necessarily translate into amniocentesis. It may be some intermediate step, depending on what the abnormality is.

REHMAll right, let's go to Chris here in Washington, D.C. You're on the air.

CHRISHi Diane, thanks for taking my call.

REHMSure.

CHRISI just wanted to share a story of my wife and I are expecting our second son in about four weeks, as a matter of fact, and use one of the blood tests that were discussing to -- just we're in our mid-30s and kind of figured why not, it's available, we'd take a shot. And thankfully we did it. At 11 weeks pregnancy, we were able to get a preliminary diagnosis of a sex chromosomal aneuploidy, 47XXY, which is something that goes amazing undiagnosed.

CHRISIt's a very common genetic disorder that the panel I'm sure can tell you more about, but unless there are physical symptoms of it, or possible developmental difficulties, you know, a child may not be -- or a man may not be diagnosed with it until adulthood. So as a result, at 10 weeks of pregnancy we were able to start doing research. We had it confirmed by a CVS. But our experience was we walked in to meet the doctor, and she didn't believe that the blood test could possibly be correct because she'd never seen that result come back and had to apologize and realize that her information was out of date and that she would have to, you know, update the way she was dealing with patients who were now getting this information.

CHRISI know it's a double-edged sword, but in our case, you know, for things like 47XXY, 47XXX, 47XYY, this is a huge opportunity for boys and girls who, you know, had previously gone undiagnosed to maybe start looking to get more research dollars on these infants and trying to look at how lifelong differences, you know, what kind of difference it makes from birth onward.

CHRISBut the challenge is information, and a lot of, a lot of doctors aren't aware of Klinefelter's. If you go into an OB's office, and you talk about your test, chances are they don't have a whole lot of information about these kinds of anomalies, just because they'd never done them prenatal diagnoses.

REHMDo you agree, Lisa?

FREESEI think that as the caller was stating, many of the sex chromosome abnormalities are not identified in the nursery or at birth so that unless there are other findings later in life, often infertility, they may go undiagnosed for an entire lifetime. And the additional screening, the new screening that we are talking about, does have some detection for increased risk for sex chromosome abnormalities. It's not as good at predicting that risk as it is, for example, for Down syndrome. So it still is not going to detect them in all cases.

FREESEAnd it's that balance of trying to look at what are the risks for finding something and what screen can provide the most information and how does a patient decide that that is a screen or a test that they want to do.

REHMLisa, what about money? How many people have access to genetic counselors like yourself?

FREESEPart of it is money, and part of it is location. Most genetic counseling is available either at low cost or at no cost just because many genetic counselors are unable to bill because of the insurance in an economy the way that physicians bill and are sometimes being used as a facilitator for physicians who would then be billing for entire services. So often it is not a cost to the patient, but some patients would have some moneys out of pocket.

FREESEI think often it is more, is there a genetic counselor available, and is there someone that can see that patient that's not just their physician in order to help with that.

REHMWhat about insurance? To what extent does insurance step in?

FREESESome insurance would cover a genetic counseling session, often if it's a licensed genetic counselor, which is not available in all states yet, and often insurance companies don't credential or cover genetic counseling by a genetic counselor. We continue to try to work with that. The National Society of Genetic Counselors continues to help us work on that.

REHMDr. Greene, I gather that these tests are not regulated by the FDA, and you've expressed some concerns about that.

GREENEYes, that's an ongoing issues. So these -- all of the current tests that are now being marketed in the United States are what are called laboratory-developed tests. And what that means is that the tests, as the name implies, have been developed in laboratories, but they're retained within the laboratory and only done within the laboratory.

GREENEAs such, in other words, the laboratories don't sell kits for other people to do this kind of testing. They're retained within the laboratory. That kind of testing, LDTs, is exempt from FDA oversight. There is a move afoot in Congress and at the FDA to extend the purview of the FDA to supervising and regulating and verifying the quality and the nature of these tests, as well as the advertising of the tests to make sure that there's truth in advertising.

GREENEBut you're right. Right now there's no FDA oversight. None of these tests have any kind of an imprimatur of the FDA that these tests are effective at doing what they're doing. The industry is perfectly happy with this situation because from their perspective, the FDA, FDA oversight would add money and time to their test development. They can be much more nimble without having to go to the FDA every time they want to add a new feature to the test or sell a new test. But there's no consumer protection here.

REHMAnd you're listening to the Diane Rehm Show. Dr. Levy, I would imagine that a worst-case scenario might mean that a woman would terminate a healthy pregnancy based on some erroneous reading of a test or even an accurate reading of the test, but it wouldn't cause a problem. Do you know how often that happens?

LEVYWe don't have data on that, and I do want to correct a number that I gave earlier, which is that .01 percent times four million is 4,000. And I thank the caller for...

REHMNot 40,000.

LEVYNot 40,000. I thank the caller for that. But I think this is where counseling and advice to our patients is so critically important. It's very difficult to explain statistics and what the numbers mean to an anxious couple but it's so critically important that we understand what these things really mean. And I think some of your callers have made that very clear, that pregnancy, childbirth is such a very unique and special situation for all of us, and our values and our judgments are colored by many, many things.

LEVYIt's very important for people to understand what these tests mean and, most importantly, what they don't mean.

REHMLisa, that's an interesting point, what they may not mean. Is it true that in some cases, genetic testing has been able to discover cancer in the mother, for example?

LEVYRight, there have been more recent studies showing that results of this new screening can show fragments of the DNA in the mother's blood that are reflective of a maternal disease rather than what might be going on in the pregnancy. And there is still a lot of controversy in what should a laboratory be disclosing to either the provider or the patient about this information because if they don't go into having blood drawn to find out if they're at risk for cancer, they're going in to find out if there's a risk to a pregnancy, how do we determine how we're supposed to represent that to the patient when it may even not be accurate but might be a predictor of disease for the mom?

REHMHave you ever encountered that, Dr. Greene?

GREENEYes, unfortunately, we certainly have. It's a well-described phenomenon at this point. When we get certain patterns of bizarre representations of fragments of chromosomes, that is -- that that may foretell the presence of a cancer in the mother that was previously undiagnosed. I believe that worldwide there is something on the order of about 50 cases like this that have already been described, and it is part of the consent process before a woman has the blood drawn that we may find out things that nobody anticipated and that certainly she didn't expect from what was thought to be just a prenatal diagnostic test for the fetus.

REHMAll right, well, we'll have to leave it there. Most interesting. Thank you all, Dr. Michael Greene, Lisa Freese, and Dr. Barbara Levy. And thanks to you for sharing your own thoughts, your own experiences. Thanks for listening. I'm Diane Rehm.