Prenatal Testing: Interview with Serdar H. Ural, M.D.

Photo of Dr. Serdar H. Ural, M.D

Regular prenatal care, proper nutrition, and getting exercise all are important parts of your job as a pregnant woman. Sometimes, those doctor visits also come with prenatal testing. Although waiting for results can be scary, it helps to have all the information you need to prepare for your child's birth.

LoveToKnow Pregnancy spoke with Serdar H. Ural, M.D., director of maternal-fetal medicine and medical director of labor and delivery at Penn State Milton S. Hershey Medical Center about what woman can expect from prenatal testing.

Popular Prenatal Testing

LoveToKnow (LTK): In a typical pregnancy, what are some of the basic prenatal tests that most pregnant women will undergo?

Serdar H. Ural. M.D. (SU): Usually, it entails blood work and looking at blood counts. It could entail a pap smear and checking for certain STDs. This is usually done very early in the pregnancy or at the first prenatal visit. After that, the American College of Obstetricians and Gynecologists suggests that OB/GYNs should offer first trimester screening to all women, including bloodwork and ultrasounds.

LTK: What are you looking for in the blood work?

SU: We look for markers that screen patients for chromosomal aberrations, such as Down Syndrome. This is not diagnostic, it is just a screening tool.

LTK: I think many women look at the ultrasound simply as a chance to learn their child's sex, but physicians use this as screening tool as well, don't they?

SU: Yes, an anatomy ultrasound typically occurs between 18-20 weeks for the most part. Again, it is a screening test that looks for markers that could indicate several chromosomal aberrations. We use it as a general screening tool to assess for markers.

LTK: If there is a suspected problem, what are some of the additional tests that may be performed?

SU: Depending on what it is, the expectant mother could have repeated ultrasounds or genetic counseling. We might also consult with other specialties depending on the abnormality. In the least severe cases, we may just do close observation.

LTK: What are some of the risk factors associated with prenatal testing?

SU: The first trimester testing has no side effects to mom or the baby. But, if it comes back abnormal, there are two invasive tests that can be offered to provide a more accurate diagnosis. Chorionic villus sampling, or CVS, is performed right after the blood tests come back. It has a miscarriage rate of 1 in a 100. The other option is amniocentesis which is usually performed around 16 weeks. That miscarriage rate is about 1 in 200 to 250.

There is some recent data that suggests that the rate of miscarriage with amnio is actually even lower, but it's not zero.

Testing Concerns and Options

LTK: What are the accuracy rates of these tests?

SU: They are generally considered 99.9 percent accurate while some places claim it's 100 percent accurate. If the results come back as normal, then the issue resolves on its own. If the results show a chromosomal problem, then the patient is aware of the problem but there is still not a treatment option.

LTK: What are some of the emerging tests that are being developed?

SU: Some research is looking at fetal DNA in maternal circulation. These are blood tests on the mom that would try to detect fetal DNA matter and the research is looking to see if this can be tested and what the accuracy is. If it's as accurate as an amnio, then it could replace it, but that technology is not here yet and the research is ongoing.

LTK: How do these tests allow the physicians to prepare for the child's birth?

SU: Unfortunately, if there does appear to be chromosomal abnormality like Down Syndrome, there is no treatment. But, we do alert the patient and have them consult with pediatricians or specialists that deal with other chromosomal abnormalities. The pediatrician consults the patient on what to expect with the baby.

LTK: Are all of these tests optional?

SU: Everything is offered but there are no rules or requirements that say a pregnant woman has to have a test. The standard of care is to offer prenatal testing options and let the patient determine what to do with the information.

Prenatal Testing Decisions

Generally, prenatal testing is safe and poses only a small risk to mothers and their babies. But only the baby's parents, in close consultation with their doctor, can make the important decision about whether or not to perform any tests.

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Prenatal Testing: Interview with Serdar H. Ural, M.D.