ExitCare ImageAmniocentesis (amnio) is the removal of a small amount of fluid that surrounds the baby in the amniotic sac. Once the fluid is removed, it may be examined to find answers to a number of serious questions. An amnio is often done early in pregnancy (between 15 and 17 weeks) to determine if there is a complication with the baby, or it is done later in pregnancy (between 33 and 37 weeks) to see if the baby's lungs are mature. Amnios that are done later in pregnancy are often done to help weigh the risks and benefits of a needed early delivery. Amnios done early in the second trimester are commonly referred to as genetic amnios, as they are typically done to check for a potential life-altering genetic abnormality. Rarely, an amnio is done to evaluate the amniotic fluid for concerns of infection.

Amniocentesis may be done for other reasons, including:

  • If the mother is 35 years old or older. This is because of the increased risk of chromosome abnormalities, such as Down's syndrome or various chromosomal trisomies.

  • To determine any genetic problems.

  • To look for signs of infection in the uterus.

  • To determine if the baby's lungs are mature enough for the baby to survive outside of the uterus. This information is important in pregnancies when the baby must be delivered early.


  • Any complications you have had with the pregnancy, such as bleeding or contractions.

  • Allergies.

  • Medicines taken, including vitamins, herbs, eyedrops, over-the-counter medicines, and creams.

  • Use of steroids (by mouth or creams).

  • Previous problems with numbing medicines.

  • History of bleeding problems or blood clots.

  • Previous surgery.

  • Other health problems.


Complications can include:

  • Vaginal bleeding.

  • Transmission of an infection from mother to baby, such as hepatitis C or other viruses.

  • Leaking of amniotic fluid.

  • Premature labor.

  • Fetal injury.

  • Injury to the placenta.

  • Miscarriage (rare).

This procedure is done only if your caregiver feels the information obtained from the procedure justifies the risk. Amnios should not be performed before 15 weeks of pregnancy unless it is absolutely necessary.


  • Ask your caregiver any questions you may have.

  • Eat as usual.

  • Drink enough fluids to keep your urine clear or pale yellow.

  • You may want to arrange for someone to drive you home after the procedure.


A careful ultrasound is done to evaluate the baby for its position and for where the best pockets of fluid lie. The mother's abdomen is prepped with a solution to prevent infections. Often, a sterile ultrasound probe is used to watch the location of the amniocentesis needle being used. A small spot of the skin may be injected with a numbing medicine. In that location, a longer needle is introduced through the skin and down to the level of the baby. Amniotic fluid is removed into a syringe and sent to the lab for evaluation.


  • Ask your caregiver if you need a RhoGam shot.

  • You will rest for 1 to 2 hours for observation.

  • Your baby will be placed on a monitor for 1 to 2 hours to see if there are any problems.

  • You may develop cramping and a small amount of vaginal bleeding right after the amnio.

  • Ask when your test results will be ready. Make sure you get your test results.