Dr. R. Curtis Rogers
The genetic counselors he supervises at Greenwood Genetic Center see about 1,000 patients each year, but countless others are never seen by a counselor.
Too often, time-pressed primary care physicians are offering the testing without allotting the necessary time for in-depth counseling, he said.
“Yes, it is an exciting test and a good test, but it certainly is not a perfect test ... and I am hesitant for families to make decisions about pregnancy management based solely on NIPS unless there were obvious birth defects detected on prenatal ultrasound that were consistent with the NIPS findings,” he said.
For example, if an ultrasound shows holoprosencephaly, and NIPS shows trisomy 13, the likelihood of trisomy 13 is greater than 95%, he explained, adding that other scenarios, such as detecting partial deletions or duplications, is much less clear.
“Most patients who receive this screening should receive genetic counseling from a certified genetic counselor prior to having the test,” he said. “When we’re talking about very significant diagnoses that may alter the management of pregnancy, I think we need to be 100% correct. Yes, there is high specificity and sensitivity, and for most of the disorders – especially the trisomies – it has good positive predictive value. But it is not perfect, and I think we need to go into that with our eyes open, and families need to go in with their eyes open.”
Jennifer Stallworth, one of the genetic counselors at Greenwood Genetic Center, explained that her role is to counsel patients who may be considering the test, including informing them about the risk for chromosomal conditions in their pregnancies, and discussing the pros and cons of NIPT, compared with other screening and diagnostic testing options.
“I also counsel patients who have already had the test completed, and whether the results are normal or abnormal, I try to help them understand how that result has changed our understanding of the risk for a chromosome disorder in the pregnancy,” she said.
She, too, noted that the excitement about these tests stems largely from a desire to improve upon existing screening methods.
“I think everyone would like to have a risk-free alternative to amniocentesis and [chorionic villi sampling], but we are not yet to that point with NIPT,” Ms. Stallworth said. “I would continue to advise doctors and patients that these tests are a good way to screen for major chromosome conditions, but it is still important to consider all of a patient’s risk factors and to remember that invasive diagnostic testing offers the most complete information at this time.”