Your pregnancy: Amniocentesis
Amniocentesis is a procedure in which amniotic fluid is removed from the uterus for testing or treatment. Amniotic fluid surrounds and protects a baby during pregnancy. This fluid contains foetal cells and various chemicals produced by the baby.
Amniocentesis can be done for various reasons:
*With genetic amniocentesis, a sample of amniotic fluid is tested for certain conditions -- such as Down's syndrome and spina bifida.
*With maturity amniocentesis, a sample of amniotic fluid is tested to determine whether the baby's lungs are mature enough for birth.
* Occasionally, amniocentesis is used to evaluate a baby for infection or other illness.
*Rarely, amniocentesis is used to decrease the volume of amniotic fluid.
Although amniocentesis can provide valuable information about your baby's health, the decision to pursue invasive diagnostic testing is serious. It's important to understand the risks of amniocentesis -- and be prepared for the results.
Genetic amniocentesis can provide information about your baby's genetic make-up. Generally, genetic amniocentesis is offered when the test results might have a significant impact on the management of the pregnancy -- or your desire to continue the pregnancy. Typically, the value of this information can only be assessed by you and your partner.
Genetic amniocentesis is usually done after week 15 of pregnancy. Rarely, genetic amniocentesis might be done as early as week 11 of pregnancy.
Maturity amniocentesis can determine whether a baby's lungs are ready for birth. This type of amniocentesis is done only if early delivery -- either through induction or C-section -- is being considered to prevent pregnancy complications for the mother. It's usually done between 32 and 39 weeks of pregnancy. Earlier than 32 weeks, a baby's lungs are unlikely to be fully developed.
Amniocentesis carries various risks, including:
*Miscarriage. Second-trimester amniocentesis carries a slight risk of miscarriage -- between one in 300 and one in 500. Research suggests that the risk of miscarriage is higher for amniocentesis done before 15 weeks of pregnancy.
*Needle injury. During amniocentesis the baby might move an arm or leg into the path of the needle. Serious needle injuries are rare.
*Leaking amniotic fluid. Rarely, amniotic fluid leaks through the vagina after amniocentesis. If the leak seals, the pregnancy is likely to proceed normally. It's possible, however, for chronic leakage to lead to orthopaedic problems for the baby.
*Rh sensitisation. Rarely, amniocentesis might cause the baby's blood cells to enter the mother's bloodstream. If you have Rh negative blood, you'll be given a drug called Rh immunoglobulin after amniocentesis to prevent you from producing antibodies against your baby's blood cells.
*Infection. Rarely, amniocentesis might trigger a uterine infection.
*Infection transmission. If you have an infection -- such as hepatitis C, toxoplasmosis or human immunodeficiency virus -- the infection might be transferred to your baby during amniocentesis.
— Mayo Clinic