Amniocentesis is a prenatal test that takes a small sample of amniotic fluid (the fluid that surrounds the fetus during pregnancy).
This fluid contains cells shed by the fetus. The cells contain genetic information that can be tested for chromosomal disorders and open neural tube defects. Your doctor may recommend amniocentesis for any of the following reasons:
Complications from amniocentesis are rare, but do occur. There is a one in 300 or less risk of losing your pregnancy from the procedure, primarily due to the chance of rupturing membrane. Later in pregnancy, ruptured membranes can lead to preterm birth. There is also a small risk of infection inside the uterus.
Amniocentesis testing usually occurs during the second trimester, but can also be done in the third trimester. Before having an amniocentesis procedure, let your doctor know if you have a history of bleeding disorders or if you are taking blood-thinning medicine, as these may affect the procedure.
In rare cases, amniocentesis can cause some of the baby’s blood cells to enter the mother’s bloodstream. Let your doctor know if you are Rh negative. If this is the case and your baby is Rh positive, your body’s immune system may produce antibodies against your baby’s blood.
During amniocentesis, an ultrasound of the abdomen helps your doctor locate the uterus and the amniotic sac. Your abdomen is cleansed with antiseptic, and you should not touch the sterilized area during the procedure.
Using the ultrasound, the doctor guides a long, hollow needle into the abdomen, through the uterus and into the amniotic sac. You may feel a slight sting as the needle is inserted, and you may feel some cramping as it enters the uterus. The doctor withdraws a small amount of the amniotic fluid into a syringe, which may feel like a tugging sensation.
A sample of amniotic fluid is sent to a lab where specialists evaluate it for genetic or chromosomal abnormalities. The fluid can also be checked for a protein that is present when there is an open neural tube defect.
Do not do any strenuous activities for at least 24 hours afterward. Some cramping is normal, but let your doctor know if you experience any of the following symptoms:
It may take a week to 10 days to receive results. Our office will call you with the results when they are available. During the call, we can arrange further follow-up that may be needed.
These valuable resources can help expectant parents become more informed about prenatal tests such as amniocentesis.
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
This organization for physicians has information for patients about screening and diagnostic tests that may be performed during pregnancy.
This U.S. government website publishes information about many types of health conditions, tests and treatments, and includes a description of prenatal testing.