Amniocentesis - Purpose & Procedure

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.


  • between 15 and 20 weeks of gestation to test for genetic diseases, chromosomal abnormalities, and open neural tube defects
  • after 32 weeks to evaluate fetal lung maturity
  • when it is suspected that a fetus has an infection or other illness
  • serially, about every 14 days, when it is suspected that a pregnant woman has an Rh or other blood type incompatibility with her fetus

Test Preparation: a full or empty bladder as instructed by your health provider


  • First, your health care provider will use ultrasound to determine the baby’s exact location in your uterus. You’ll lie on your back on an exam table and expose your abdomen. Your health care provider will apply a special gel to your abdomen and then use a small device known as an ultrasound transducer to show your baby’s position on a monitor.
  • Next, your health care provider will clean your abdomen with an antiseptic. Generally, anesthetic isn’t used. Most women report only mild discomfort during the procedure.
  • Guided by ultrasound, your health care provider will insert a thin, hollow needle through your abdominal wall and into the uterus. A small amount of amniotic fluid will be withdrawn into a syringe, and the needle will be removed. The specific amount of amniotic fluid withdrawn depends on the number of weeks the pregnancy has progressed.
  • After the amniocentesis, your health care provider will continue using the ultrasound to monitor your baby’s heart rate. You might experience cramping or mild pelvic discomfort after an amniocentesis.
  • You can resume your normal activity level after the procedure. However, you might consider avoiding strenuous exercise and sexual activity for a day or two.


* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.