Amniocentesis: What is it?

It is a procedure in which a small amount of the amniotic fluid (about 20 cc) surrounding the fetus is withdrawn for testing for chromosomes and genetic disease.

This is done by inserting a very fine needle through the mother’s abdomen into the uterus under ultrasound guidance.

The procedure is performed on an outpatient basis and takes only a few minutes.

Most women do not experience any pain and a local anesthetic is not necessary. The needle may cause some pain when it penetrates the uterus, but the pain should not last long and should not hurt more than an injection into any other part of the body.

After the fluid has been withdrawn, the removal of the needle will cause no further discomfort. The fluid is then sent to the laboratory for analysis.

Why is Amniocentesis necessary?

The majority of amniocentesis are done for the detection of chromosomal disorders.

Chromosomes carry genes that pass certain characteristics from parents to their children. When there are too many or too few chromosomes or there is a defect in a chromosome, birth defects can occur.

Down Syndrome is the most common chromosomal disorder. It causes mental retardation and other health problems such as heart defects. Other less common chromosomal disorders may lead to serious handicaps and death.

When is Amniocentesis performed?

Amniocentesis is usually performed between 16th to 20th weeks of pregnancy.

When will the result be available? 

Usually it takes about 2–3 weeks. If you wish, a rapid test can provide a preliminary report in 3 working days (additional charge applies).

Can all birth defects be detected?

No. Amniocentesis can detect almost all known chromosomal disorders. However, birth defects not due to chromosomal abnormalities cannot be detected through this test.

Who should consider Amniocentesis?

• Women whose First Trimester Screening or Maternal Serum Screening or Non Invasive prenatal testing test results shows a “High Risk” for Trisomy 21 or 13 or 18.
• Women who know that they or their partners carriers of a known genetic disease.
• Women who had an early ultrasound report shows that the fetus has structural defects which are associated with chromosomal
• Women who have had a child with Down Syndrome or other chromosomal disorders.
• Women who know that they or the partners have an unusual chromosome arrangement  

There may be other reasons that apply uniquely to you.  Both you and your obstetrician should decide together if you need an Amniocentesis.

Is Amniocentesis safe?

Amniocentesis is a safe, low risk procedure when done by experienced medical experts. The risk of miscarriage following the test is reported to be 0.3-0.5%

Useful Information

No fasting is required for the procedure

Activity – You should be able to return to your normal activities within a few hours after the procedure.

Rest – If you ae working, you will be given a medical certificate for the day of the procedure.

Medication – Some hormonal support in the form of oral tablets will be given after the procedure.

Diet – There are no dietary restriction relating to this procedure

Return to the Hospital or call your obstetrician if: 

• You run a fever
• You feel nauseous or have vomiting
• You experience any unusual lower abdominal pain
• You notice vaginal bleeding 
• You notice leakage of fluid from the vagina