By Dr. Kate Scannell, Syndicated Columnist
First Published in Print: 08/21/2011
You've got to be very careful if you don't know where you are going, because you might not get there. -- Yogi Berra
CONCEIVABLY, baseball legend Yogi Berra might have been referring to modern birthing trends. With new medical technologies constantly altering the conditions for human conception and birth, it's not always clear where we're going -- and if we're going to get there.
Last week, modern science threw another fastball when researchers claimed in the Journal of the American Medical Association that you could determine the sex of a fetus as early as seven weeks in its development in 95 percent of cases.
More remarkably, this determination could be made by sampling the mother's blood -- avoiding the risky and invasive methods we used to employ for fetal-DNA sex detection in the ancient days of ... well, yesterday.
Savvy readers may ask why this study is noteworthy. After all, since 1997 we've known that maternal blood carried free-floating fetal DNA, which could be analyzed for telltale evidence of either male (XY) or female (XX) chromosomes. Moreover, medical clinics in other countries have been offering maternal blood testing for fetal sex determination for years. And, not surprisingly, private companies have been marketing maternal blood and urine tests to consumers over the Internet, promising accuracy rates as great as 99 percent as early as 5-to-7 weeks' of gestation.
But the new study is radical because its researchers dared to test the test itself. They noted that its widespread clinical use and Internet commerce were proceeding merrily along, all the while without a formal analysis of the test's accuracy and reliability. And after evaluating 57 studies involving maternal blood or urine testing for fetal DNA sex determinations, they made two critical observations that, hopefully, will impact clinical practice and website claims.
First, they firmly established that maternal urine testing was unreliable. Secondly, they demonstrated that blood testing could reach 95 percent predictive accuracy only if performed no earlier than seven weeks of gestation.
It seems hard to believe that it took so long for this rigorous assessment. After all, a momentous decision often rests upon the test results: that is, whether a woman decides to continue her pregnancy. For women hoping to minimize the risk of birthing children with certain medical or genetic disorders, the result would reveal whether the fetus belonged to the sex linked with those disorders. And for a woman intent on choosing her child's sex as a matter of personal preference, the result could sway her decision about proceeding with pregnancy.
Great moral questions attach to these decisions based upon these tests. Abortion -- whether for medical, cultural, or personal reasons -- has always incited heated ethical debates within this country and elsewhere.
Using medical tests or technologies to limit human subpopulations with various medical conditions or genetic traits has remained ethically divisive -- upheld by some as a moral and medical good, but reviled by others as discriminatory, devaluing, and dehumanizing.
Moral support and coexisting disapproval also surround the issue of parents choosing the sex of their children as a matter of personal preference. Is it sexist or dehumanizing to prefer one over the other, as some claim? Or have we arrived at a consensus that it is no less morally problematic than choosing the sex of an adopted child or aiming for "family balance"? What will happen to a child selected for its sexual identity who later disappoints parental expectations of its gender? Will sex selection lead to problematic gender imbalances within the population, as has already occurred in China and India where, for centuries, females have been devalued and "de-selected"?
The main point is that, with many new medical tests, it's not always clear what it is that we are actually measuring or evaluating. And it's not always evident what moral issues are being tested. We need to stay vigilant if we don't know where the tests will lead us, because, as Berra notes, we might not get there.
At a minimum, we should be reliably certain about the accuracy of diagnostic tests to deliver expected information -- before those tests reach prime time, before they're hyped and sold for commercial profit, before they become instant Internet célebre-tests, before people make momentous life decisions based upon the results.
Within the last few weeks alone, the World Health Organization also called for a ban on blood tests to detect tuberculosis because, "based on the evidence, (these) tests lead to misdiagnosis and mistreatment of patients" and constitute "a waste of time and resources." In July, expensive gene-based tests used at Duke University to determine chemotherapy regimens for cancer patients were proven worthless, and the research backing their use was discredited.
The impact of bad testing on good medical practice can be enormous, especially when their target populations include many millions of people -- pregnant women, people with tuberculosis, patients with cancer. When a test is too untested or when it is misapplied, real people suffer the consequences and health care costs needlessly escalate.
Meanwhile, today I found Internet offers for $25 discounts on in-home kits for maternal blood testing to determine fetal sex. On Amazon, the urine "gender prediction test" is on sale -- up to 41 percent off. And what a bargain — there's a $58 discount on blood tests for TB!
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Kate Scannell is a Bay Area physician and the author of "Flood Stage."
Copyright, 2011, Kate Scannell