A challenging test for OB-GYNs

There is a risk of miscarriage when doctors perform a test on pregnant women to see if their fetus has Down syndrome, a Tufts Medical Center obstetrician-gynecologist writes in today's Wall Street Journal.

Dr. Adam Wolfberg says he recently referred a patient to a more experienced doctor to do the test, called chorionic villus sampling for the cells a needle siphons from the placenta. He based his decision on reports that show the more CVS procedures a doctor does, the fewer miscarriages. The risk is estimated to be about 1 percent, higher than for amniocentesis, which is performed later in pregnancy.

That raises the question of how to acquire proficiency.

"CVS mavens got that way by practicing, so their present-day patients benefit at the expense of previous patients," Wolfberg writes.

Fewer than 100 doctors are trained in CVS in the United States each year, he writes, meaning there aren't enough doctors to meet demand. After performing his 15th supervised CVS, he is considered trained. None of his patients miscarried.

"I have colleagues who have done the procedure 1,500 times, but they are swamped and I probably won't refer my patients to them," he writes. "I'll do CVS myself."