MEDICAL ANIMATION TRANSCRIPT: Amniocentesis is a procedure that lets doctors detect or rule out problems with your baby's health long before birth. In the uterus, your baby is surrounded by amniotic fluid that provides protection and nourishment. Floating in the fluid are cells from your baby, providing doctors with genetic material for testing. In amniocentesis, your doctor will take a sample of this fluid to test for specific genetic disorders and birth defects. Amniocentesis is usually done in the second trimester of pregnancy at 15 to 18 weeks. It is generally offered to women with certain risk factors. Age 35 or older, which increases the risk of chromosomal disorders, such as Down Syndrome. A previous child or pregnancy with a birth defect. Blood test or ultrasound suggesting a birth defect, such as Down Syndrome or neural tube defects. Or a family history of genetic disorders, such as cystic fibrosis. Amniocentesis may also be done in the third trimester for these reasons. To determine if the baby's lungs are mature enough should early delivery become necessary, to diagnose a uterine infection or to check for anemia in a baby with RH incompatibility. To begin your procedure, your doctor would use ultrasound to create an image of the fetus and nearby structures on a computer screen. Looking at this image, the doctor can choose a safe place to insert the needle. Your doctor may give you an injection of local anesthesia to numb the surface of your abdomen where the amniocentesis needle is to be inserted. Carefully watching the ultrasound monitor to avoid contact with the placenta or the baby, your doctor will introduce the thin needle through your abdominal wall into your uterus and into the amniotic sac. He or she will then withdraw a small sample of amniotic fluid, remove the needle, and cover the site with a bandage. Your body will make additional fluid to replace what was removed. Your doctor will continue to monitor the ultrasound to check that the fetal heartbeat is normal and the baby tolerated the procedure well. You may feel mild cramping or pressure in your lower abdomen for about 24 hours after your procedure. You will be advised to avoid physical stress, such as vigorous exercise, lifting, prolonged standing, and sexual activity.