Prenatal Screening Tests
Nantucket Cottage Hospital offers prenatal screening tests to screen for a variety of disorders.
This diagnostic test offered to women over age 35 or with a family history of genetic abnormalities. A thin needle passed through the mother’s abdomen into the uterus obtains a sample of amniotic fluid. Cells from this fluid are grown in a genetic laboratory for two weeks. The chromosomes are then studied for Down’s syndrome and other chromosomal abnormalities. We provide genetic counseling at the time of amniocentesis and again in more detail should an abnormality be detected. In the third trimester, this test can also be administered to analyze for chemicals that indicate fetal lung maturity.
Ashkenazi Jewish Carrier Screening
Distinct ethnic groups are known to have an increased risk for particular genetic diseases. In the Ashkenazi Jewish (Eastern European) population, several inherited diseases are known including Cystic Fibrosis, Tay-Sachs disease, Canavan disease and familial dysautonomia. There are a number of other disorders that occur more often in the Ashkenazi Jewish population for which carrier testing is also available. Interested couples can have a blood test to learn about their chances of having a child affected with one of these conditions.
Biophysical Profile (BPP)
The BPP uses ultrasound to observe amniotic fluid volume and fetal activity, muscle tone and breathing. It is performed in certain circumstances in the third trimester.
This test determines your blood type. For women whose blood type is RH negative, an injection of Rhogam is given at 28 weeks of pregnancy and again postpartum if your baby is RH positive. These injections prevent antibody formation which could affect future pregnancies.
The Glucose Loading Test (GLT), usually performed at 26 to 28 weeks, is a blood test performed one hour after taking a flavored glucose drink. It screens for diabetes which may arise during pregnancy. There is no fasting preparation for this test. An elevated GLT indicates the need for further testing.
Group B. Streptococcus (GBS)
GBS is a common bacterium that normally lives in the vaginal or gastrointestinal tracts of about 25 percent of healthy adult women. Although rare, it can become an issue when it is found in the vagina during delivery, where it can cause serious infections for both mother and baby. Women are screened for GBS between the 35th and 37th weeks of pregnancy. A swab sample is taken from both the vagina and rectum; test results are usually available within 24 to 48 hours. Positive tests may result in antibiotic treatment during labor.
This blood test determines anemia.
This virus can cause illness which may or may not be obvious. It infects the liver and can cause liver damage that may persist for long periods of time. Even if you have never had symptoms of Hepatitis B, if it is in your blood, you can pass the disease on to your infant at birth. Infants who are born to women with Hepatitis B in their bloodstream should receive treatment at birth to prevent serious liver damage.
HIV, the virus that causes AIDS, is a sexually transmitted disease which may take years for symptoms to occur. Therefore, many people who are infected with the HIV virus don’t know it. A pregnant woman who has been exposed to the HIV virus can pass it on to her baby. Certain behaviors put a woman at risk for contracting the virus, such as: using injection drugs; having unprotected sex (sex without a condom); receiving a blood transfusion prior to 1985. A blood test, which is offered to all patients, and encouraged, determines if you have been exposed.
Non-Stress Testing (NST)
This test assesses fetal well-being by monitoring the fetal heart rate. Testing may take up to 40 minutes.
Rubella (German Measles)
Screening This disease can cause birth defects if a pregnant woman contracts it during early pregnancy. Once a person has had rubella, he or she cannot get it again. This test indicates whether a person has ever had the infection or has ever been vaccinated against it.
Screening for Chromosomal Disorders
The blueprint of the body is ‘written’ in DNA, and genes correspond to words. These words are grouped together into chapters of varying lengths called chromosomes. We get one set of 23 chromosomes from each parent, for a total of 46. When a baby is conceived with an abnormal number of chromosomes, there can be varying degrees of problems after birth. Examples of chromosomal disorders are Down syndrome, Trisomy 13 and Trisomy 18. Screening for these disorders may involve ultrasound and a maternal blood sample at a certain time in pregnancy to determine the probability for the baby to have one of these disorders. There are many options of screening for chromosomal disorders including early risk assessment (ERA), quad screening and cell free DNA testing.
Syphilis is an infection which can be present without causing any symptoms and can be passed from a pregnant woman to her unborn child. This is one of the maternal infections that can be harmful to the baby. The blood test screens for this.
Tuberculosis (TB) Screening
This screening is a simple skin test that detects the presence of TB, a highly contagious, serious infection most commonly located in the lungs.
This is a diagnostic test which uses sound waves to produce an image of the fetus before birth. We recommend this test for specific indications, such as vaginal bleeding, the question of twins or assessment of fetal growth.