January 21, 2022 by John Fernandez
Test Detects Birth Defects
For every pregnant woman who hears her obstetrician say, “Your baby is healthy”, it’s like hearing magic words. Anxiety changes to joy – particularly for women whose pregnancies are at risk for life-threatening chromosomal abnormalities. Thanks to important medical advancements in both testing and procedures, there is good news for the millions of women who have blood tests to screen for serious problems, or fear the complications of pre-term labor.
A new test now provides far more accurate results than standard tests, while life-saving procedures are allowing doctors to say those magic words more often, said Jorge Perez, M.D., medical director of South Miami Hospital’s Neonatal Intensive Care Unit, a part of its Center for Women and Infants.
“Years ago when I started practicing, these issues were basically a surprise, but with the advancement of prenatal care and maternal-fetal medicine and the awareness the March of Dimes has promoted over the years, it’s now unusual not to know something prior to the baby’s delivery,” he said. “Chromosomal abnormalities occur in about one out of every 160 live births, so it’s pretty common when you think there are about four million live births in the U.S. per year.”
Cell-Free DNA testing (cfDNA)
“The new cell-free DNA test or cfDNA, significantly reduces false alarms and can be given as early as ten weeks,” said Jason James, M.D., chair of the Department of Obstetrics and Gynecology at Baptist Hospital. “It has the potential to revolutionize the whole field of prenatal screening,” he said. The accuracy of the test, he says, also decreases the need for the two more invasive tests – amniocentesis and chorionic villus sampling, or CVS, – both of which carry a risk of miscarriage.
The cfDNA test screens for three specific abnormalities – Down Syndrome (trisomy 21), Edwards Syndrome (trisomy 18) and Patau Syndrome (trisomy 13). The test is able to assess small amounts of fetal DNA in the mother’s blood. Results are usually returned in a week, he said.
The test is specifically for screening, however, and does not replace amniocentesis and CVS to confirm abnormal results.
“Any of our high-risk patients, those with a child born with a chromosomal abnormality, or a patient 35 or over, more often than not are receiving this test,” Dr. James said.
While cfDNA has been on the market for about two years, its use has been limited to high-risk cases, Dr. James said. However, recently published research has shown that in comparison to traditional screening, the test has higher accuracy rates in the general population as well. Published in The New England Journal of Medicine, the report showed that in a study of almost 2,000 women, the rate of false positives was ten times lower than regular screening tests.
Currently insurance companies do not cover the test for the general population, but the new research could one day change that, Dr. James said. The cfDNA test is about 99 percent accurate, he said.
“Hopefully it results in a lot less anxiety,” said Dr. James, who along with Dr. Perez, is involved with the March of Dimes prevention efforts as an advocate and lecturer.
What happens if screening and follow-up tests confirm a birth defect or other abnormality? The Center for Women & Infants helps families prepare for a reality they could not have imagined, said Dr. Perez. Some cases involve children with abnormalities or potentially fatal medical conditions.
As soon as the problem is confirmed, said Dr. Perez, the family receives prenatal counseling at the Center, but is also referred to a geneticist. The geneticist consults with both the family and a multidisciplinary team of doctors participating in the care of both the mother and the baby.
Dibe Martin, M.D., a perinatologist affiliated with the Center for Women and Infants, cares for both mothers and babies in high-risk pregnancies, and is often part of treatment teams. The Center has a Maternal-Fetal Special Care Unit for high risk pregnancies, including women carrying babies with birth defects. Along with compassion and medical knowledge, Dr. Martin said, the services of South Miami Hospital’s patient care navigator are invaluable to many women. Anxious patients often run the gauntlet of doctors and appointments, and have questions about their care, at a time when they feel least able to cope. The patient care navigator handles appointments and even helps out-of-town patients find transportation and housing, she said.
With the family and extended family – which may include clergy or close friends – the team develops a plan. The plan not only includes medical expertise, but the parents’ needs and wishes.
“It’s very important for us to be good listeners, to listen to what their needs and wants are and then facilitate those needs and wants,” Dr. Perez said.
“We develop a plan so if that patient comes in at 3 in the morning, everybody is on the same page. We talk to everybody,” he said, “We disseminate that information, and we abide by that plan. There’s no one who knows better, what they want for their child than the parents.”