September 4, 2015
On a typical day at Women’s Contemporary Care Associates in Long Island, NY, many anxious pregnant women wait to see Martin Chavez, MD, FACOG, a maternal-fetal medicine specialist.
Pregnant women come to see him only for those pregnancies where either mom or baby is at risk of having complications, heightening the normal worries and fears that accompany pregnancy. These women have been referred by another physician, most often their obstetrician, to see Dr. Chavez for further testing and specialized care, both for themselves and their developing baby(ies). When he walks into the room, he brings a sense of authority and reassurance to his patients that they will be well cared for.
In practice for more than 12 years, Dr. Chavez and his team cares for more than 4,500 women each year. He views every patient as a unique case, each with nuance and intricacies. In order to provide the best patient care, he constantly reviews the latest medical journals, attends medical conferences and stays at the forefront of technological innovation in this field. As a leading physician in maternal-fetal medicine, Dr. Chavez also evaluates the most advanced technical innovations and incorporates those he supports into his patient care regimen.
In the last several years, a new test to detect the presence of an abnormal number of chromosomes in the fetus (fetal aneuploidy) represents one of the biggest changes in Dr. Chavez’s practice. Called non-invasive prenatal testing (NIPT), the test evaluates cell free DNA found within a blood sample from the pregnant woman.
NIPT is able to detect a fetal aneuploidy that could result in genetic syndromes such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18) and Patau syndrome (Trisomy 13) and also abnormalities in the sex chromosomes X and Y.
Dr. Chavez served as an investigator in the clinical study to evaluate the safety and efficacy of this test, and was one of the first physicians in New York to incorporate the test for patients in his practice.
“The practice of maternal-fetal medicine evolved rapidly with the introduction of NIPT, and my practice along with it,” says Dr. Chavez. The American College of Obstetricians and Gynecologists and the Society for Maternal Fetal Medicine currently recommend this test for women at high risk of having a fetal aneuploidy, and a large number of Dr. Chavez’s patients fit this description.
Dr. Chavez believes NIPT allows him to make decisions about best clinical practice – how often a patient should be seen, when to worry and when not to worry. He is confident in the results, particularly as it compares to prior methods of testing, called serum screening. He believes that NIPT provides increased accuracy, sensitivity and specificity, and avoids the need for a large number of unnecessary invasive procedures.
“For me, it’s particularly rewarding to know I can help two patients at once; one just happens to be on the inside.”
To hear more about NIPT from Dr. Chavez, watch his video interview below. Continued below.
More information about NIPT
NIPT available today analyzes DNA found in a pregnant woman’s blood to detect missing or extra chromosomes in the fetus. Chromosomes normally come in pairs. Healthy people usually have 23 pairs of chromosomes, the last pair of which determines sex. Men normally have an XY pair of sex chromosomes. Women normally have an XX pair of sex chromosomes. Sometimes, a genetic change happens to cause an extra or missing chromosome, referred to as aneuploidy. Most NIPT today detects Down syndrome (trisomy 21 or T21), Edwards syndrome (trisomy 18 or T18), Patau syndrome (trisomy 13 or T13), and sex chromosome aneuploidies.
In addition to NIPT, there are a number of genetic testing options available for expectant women and their health care providers. Traditional serum screening tests are used to predict the chance of a pregnancy having certain chromosomal conditions and neural tube defects (NTDs). Some screening tests require more than one office visit to perform multiple blood draws and ultrasound examinations at very specific times during pregnancy. Results from screening tests usually provide a “risk score” (such as 1 in 500 or 1 in 50) that describes the chance of a baby having a certain aneuploidy.
The serum screening tests do not provide definitive answers and can have a relatively high rate of “false negative” or “false positive” results. It is important to note that, while NIPT provides very useful information for pregnant women and their families regarding chromosomal abnormalities, there is additional information about potential birth defects that are provided by ultrasound and serum screening and these remain the standard to detect neural tube disorders.
Diagnostic tests, such as amniocentesis or chorionic villus sampling (CVS), can accurately determine whether a pregnancy has trisomy 21 (Down syndrome) and other chromosomal conditions. However, the invasive nature of these procedures poses a risk of complications, including miscarriage. Many women fear these complications and opt for NIPT, which poses no risk to the mother or her fetus.
For more information about Illumina’s noninvasive prenatal testing options, please visit our website.