Amniocentesis is done by withdrawing 1/2 to 1 ounce of amniotic fluid from one of the pockets of amniotic fluid that surrounds the baby in the uterus. An ultrasound examination with the amniocentesis shows the doctor precisely where the baby, placenta, umbilical cord, and pockets of fluid are located.
The procedure is relatively painless. Local anesthetic numbs the skin before the doctor inserts the long, thin needle into the uterus. Most women say they just feel pressure as the needle goes in, but not pain. The procedure takes 10 to 15 minutes to complete.
Intermittent cramping may be felt after the amniocentesis, but it usually subsides within a couple of hours. Occasionally, a small amount of amniotic fluid leaks from the vagina. The small leak quickly seals over, and newly manufactured amniotic fluid replaces the lost fluid without harming the baby. If the leaking continues, call your doctor. Refrain from douching, intercourse, and use of tampons until your doctor can evaluate the leaking.
The incidence of complications for amniocentesis is 1 percent – extremely low. The potential risks, such as preterm labor or sticking the baby, cord, or placenta with the needle, are more hypothetical than real, particularly when used with ultrasound guidance. Amniocentesis is widely used and considered an important tool to help your doctor make an appropriate and a safe obstetrical decision for both you and your baby.
Common Uses for Amniocentesis
1. Genetic studies and counseling that indicate inherited diseases such as Tay-Sachs disease or chromosome disorders such as Down’s syndrome (mongolism). Testing can be done at 15 to 18 weeks when there’s sufficient amniotic fluid for a specimen.
2. Neural tube defects suspected – spina bifida (spinal cord not covered and anencephaly – deformed head with exposed brain).
3. Fetal lung maturity. If your due date is uncertain or if preterm labor threatens, amniotic fluid analysis can determine whether or not the attempt should be made to stop labor.
4. Rh disease where blood incompatibility is a factor. The test can determine the amount of bilirubin (decomposed red blood cells) in the amniotic fluid. High rates of bilirubin may indicate that the baby is severely anemic and needs to be delivered.