All Medical Procedures

Amniocentesis is a procedure in which amniotic fluid is removed from the uterus for testing or treatment. Amniotic fluid is the fluid that surrounds and protects a baby during pregnancy. This fluid contains fetal cells and various chemicals produced by the baby.

Amniocentesis can be done for various reasons:

  • With genetic amniocentesis, a sample of amniotic fluid is tested for certain conditions — such as Down syndrome and spina bifida.
  • With maturity amniocentesis, a sample of amniotic fluid is tested to determine whether the baby's lungs are mature enough for birth.
  • Occasionally, amniocentesis is used to evaluate a baby for infection or other illness.
  • Rarely, amniocentesis is used to decrease the volume of amniotic fluid.

Although amniocentesis can provide valuable information about your baby's health, the decision to pursue invasive diagnostic testing is serious. It's important to understand the risks of amniocentesis — and be prepared for the results.

Chorionic villus sampling (CVS) is a prenatal test in which a sample of chorionic villi is removed from the placenta for testing.

During pregnancy, the placenta provides oxygen and nutrients to the growing baby and removes waste products from the baby's blood. The chorionic villi are wispy projections that make up most of the placenta and share the baby's genetic makeup.

Chorionic villus sampling can reveal whether a baby has a chromosomal condition, such as Down syndrome. Chorionic villus sampling can also be used to test for other genetic conditions, such as cystic fibrosis.

Although chorionic villus sampling can provide valuable information about your baby's health, the decision to pursue invasive diagnostic testing is serious. It's important to understand the risks of chorionic villus sampling — and be prepared for the results.

Cordocentesis — also known as percutaneous umbilical blood sampling — is a highly specialized prenatal test in which a sample of the baby's blood is removed from the umbilical cord for testing.

Cordocentesis can be used to detect certain blood conditions and infections. Cordocentesis can also be used to deliver blood transfusions and medication to a baby through the umbilical cord.

Use of cordocentesis is decreasing, however, since newer forms of technology can sometimes provide the same information from tests that pose a smaller risk of miscarriage — such as amniocentesis or chorionic villus sampling.

Cordocentesis might be offered when:

  • The desired information can't be obtained any other way
  • Results from other prenatal tests are unclear
  • Test results might have a significant impact on the immediate management of the pregnancy

Fetal fibronectin is a protein that acts as a "glue" during pregnancy, attaching the amniotic sac — the fluid-filled membrane that cushions your baby in the uterus — to the lining of the uterus.

Fetal fibronectin is often present in vaginal discharge before week 22 of pregnancy. Fetal fibronectin also begins to break down and can be detected in vaginal discharge toward the end of pregnancy.

If your health care provider is concerned about preterm labor, he or she might test a swab of secretions near your cervix for the presence of fetal fibronectin between week 22 and week 34 of pregnancy. A positive fetal fibronectin test is a clue that the "glue" has been disturbed and you're at increased risk of preterm labor.

A fetal ultrasound, or sonogram, is an imaging technique that uses high-frequency sound waves to produce images of a baby in the uterus.

Fetal ultrasound images can help your health care provider evaluate your baby's growth and development and determine how your pregnancy is progressing. A fetal ultrasound might also give you the chance to study your baby's profile months before delivery. In some cases, fetal ultrasound is used to evaluate possible problems or confirm a diagnosis.

Fetal ultrasound is often done during the first trimester to confirm and date the pregnancy and again during the second trimester — between 18 and 20 weeks — when anatomic details are visible. If your baby's health needs to be monitored more closely, ultrasounds might be repeated throughout the pregnancy.

Gene therapy is a treatment that involves altering the genes inside your body's cells to stop disease.

Genes contain your DNA — the code that controls much of your body's form and function, from making you grow taller to regulating your body systems. Genes that don't work properly can cause disease.

Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight disease. Gene therapy holds promise for treating a wide range of diseases, including cancer, cystic fibrosis, heart disease, diabetes, hemophilia and AIDS.

Researchers are still studying how and when to use gene therapy. Currently, in the United States, gene therapy is available only as part of a clinical trial.

Genetic testing involves examining your DNA, the chemical database that carries instructions for your body's functions. Genetic testing can reveal changes or alterations in your genes that may cause illness or disease.

Although genetic testing can provide important information for diagnosing, treating and preventing illness, there are limitations. For example, if you're a healthy person, a positive result from genetic testing doesn't always mean you will develop a disease. On the other hand, in some situations, a negative result doesn't guarantee that you won't have a certain disorder.

Talking to your doctor or a genetic counselor about what you will do with the results is an important step in the process of genetic testing.

The quad screen — also known as the quadruple marker test or simply the quad test — is a prenatal test that measures levels of four substances in a pregnant woman's blood:

  • Alpha-fetoprotein (AFP), a protein made by the developing baby
  • Human chorionic gonadotropin (HCG), a hormone made by the placenta
  • Estriol, a hormone made by the placenta and the baby's liver
  • Inhibin A, another hormone made by the placenta

Typically, the quad screen is done between weeks 15 and 20 of pregnancy — the second trimester.

Results of the quad screen indicate your risk of carrying a baby who has certain chromosomal conditions, such as Down syndrome. The alpha-fetoprotein part of the test can help detect neural tube defects, such as spina bifida.

If your risk level is low, the quad screen can offer reassurance of a healthy pregnancy.

If your risk level is moderate or high, you might choose to follow the quad screen with another test that's more definitive.