According to the U.S. Department of Health & Human Services your spouse may need other lab tests, like blood or urine tests, cultures for infections, or ultrasound exams in the first trimester, for special genetic or medical reasons. The doctor will discuss them with you and your spouse during your visits. The most common tests recommended in the first trimester include:
Nuchal translucency screening (NTS)
This new type of screening can be done between 11 and 14 weeks of pregnancy. It uses an ultrasound and blood test to calculate the risk of some birth defects. Doctors use the ultrasound exam to check the thickness of the back of the fetus' neck. They also test your spouse’s blood for levels of a protein called pregnancy-associated plasma protein and a hormone called human chorionic gonadotropin (hCG). Doctors use this information to tell if the fetus has a normal or greater than normal chance of having some birth defects.
In an important recent study, NTS found 87% of cases of Down syndrome when done at 11 weeks of pregnancy. When NTS was followed by another blood test done in the second trimester (maternal serum screening test), 95% of fetuses with Down syndrome were identified. Like all screening tests, the results are sometimes misleading. According to the U.S. Department of Health & Human Services, in 5% of women who have NTS, results show that their babies have a high risk of having a birth defect when they are actually healthy. This is called a false positive.
To find out for sure if the fetus has a birth defect, NTS must be followed by a diagnostic test like chorionic villus sampling or amniocentesis. NTS is not yet widely used. If you and your spouse are interested in NTS, talk to your doctor. If she is unable to do the test, she can refer you to someone who can. Your spouse should also call her insurance company to find out if they cover the cost of this procedure.
According to the U.S. Department of Health & Human Services, NTS allows women to find out early if there are potential health problems with the fetus. This may help them decide whether to have follow-up tests.
Chorionic villus sampling (CVS)
CVS is performed between 10 and 12 weeks of pregnancy. In CVS, the doctor inserts a needle through the abdomen or inserts a catheter through the cervix to reach the placenta. The doctor then takes a sample of cells from the placenta. Experts use this sample to look for problems with the baby's chromosomes. This test cannot find out whether your baby has open neural tube defects.
According to the U.S. Department of Health & Human Services, about 1 in 200 women have a miscarriage as a result of this test.