AMNIOCENTESIS
Amniocentesis is a prenatal test in which a small amount of amniotic fluid is removed from the sac surrounding the fetus for testing.
- Amniotic fluid is a substance much like water that surrounds and protects the fetus during pregnancy.
- Amniotic fluid contains live fetal cells and other substances, such as alpha-fetoprotein (AFP).
- These cells can be used to provide genetic and other important information about the health of the fetus before birth.
- Amniocentesis is not necessary for every pregnancy, but if tests and ultrasounds screening for abnormalities raise danger about a potential birth defect, an amniocentesis may be carried out.
WHY IS AMNIOCENTESIS PERFORMED?
Prior to amniocentesis, a complete anatomical ultrasound will be done to look for certain types of birth defects, such as Down syndrome.
Because genetic amniocentesis presents a small risk for both the mother and her baby, it is offered only to women who have a significant risk for genetic disorders. These may include women with:
- A family history of a specific genetic condition
- A partner that is a known carrier of a genetic condition such as cystic fibrosis, sickle cell disease, and similar diseases
- Abnormal ultrasound findings or abnormal lab screens
- You are older than 35 years of age
- A previous child or pregnancy with a birth defect or neural tube defect (a serious abnormality of the brain and spinal cord).
Genetic amniocentesis is usually done between weeks 15 and 20 of pregnancy. Any amniocentesis that is done earlier than that may result in a higher rate of complications.
Complications during pregnancy that may require the delivery of the baby earlier than the full term may also require amniocentesis. Fetal lung maturity amniocentesis can determine whether the baby’s lungs are mature enough to allow the child to survive outside the womb. This is usually done between 32 and 39 weeks of pregnancy. A baby’s lungs are unlikely to be fully developed earlier than 32 weeks.
Amniocentesis may also be performed if your doctor suspects that the fetus has an infection or anemia.
If you are having an amniocentesis, you may recommend finding the baby’s sex. This is the most accurate way to determine the baby’s gender before birth.
Amniocentesis will not detect birth defects such as cleft palate, cleft lip, club foot, or heart defects.
HOW IS THE PROCEDURE CARRIED OUT?
The test is an outpatient procedure, so it won’t be necessary for you to stay in the hospital.
An ultrasound is first performed to determine the exact location of the baby in your uterus.
You will lie on your back on an exam table while your abdomen is exposed.
An antiseptic is then used to clean your abdomen. Generally, anesthetic is not used.
Guided by ultrasound, a thin hollow needle is inserted through your abdominal wall into your uterus, withdrawing a small amount of amniotic fluid.
The sample of the amniotic fluid is then sent to the lab for analysis
The result of genetic amniocentesis is usually available within a few days, while fetal lung maturity amniocentesis is usually available within a few hours.
RISKS
- Leaking amniotic fluids through the vagina’\
- Miscarriage
- Needle injury
- Uterine infection
- Infection such as hepatitis C, toxoplasmosis or HIV/AIDS may be transferred to the baby. This is why amniocentesis may be discouraged if you have such infections.
Contact your health care provider if you experience certain symptoms after your procedure, such as:
- Fever
- Lack of fetal movement or abnormal fetal activity
- Redness or inflammation on the spot where the needle was inserted
- Vaginal bleeding
- Severe uterine cramping that lasts more than a few hours.
RESULTS
A genetic doctor or your health care provider may help you understand your result. Genetic amniocentesis can be reliable to diagnose genetic conditions. If a genetic condition is indicated, you might be faced with hard decisions such as terminating the pregnancy.
Fetal lung maturity amniocentesis can indicate a baby’s lung maturity. This can offer assurance that a baby is ready for the birth if it is needed that a baby is delivered early.