Women's Services Encyclopedia

Amniocentesis

Approximately 3-5% of newborns can have a birth defect. In some instances the risks may be greater (parents at risk for certain family diseases). For this reason, amniocentesis has been used for early recognition of potentially serious birth defects.

A local anesthetic is used. A needle is inserted through the mother’s abdomen into the uterus. The baby is floating in the amniotic fluid, an environment of liquid which protects the fetus and contains the chemical by-products of its development. The analysis of this fluid can give important clues to the health status and genetic makeup of the baby.

Not all birth defects can be detected through amniocentesis. Congenital heart disease, cleft lip and palate, and some forms of mental retardation cannot be diagnosed.

Genetic problems such as Down’s syndrome, spina bifida (incomplete closure of the spinal canal), and a large number of rare inheritable metabolic disorders can be detected.

Indications for amniocentesis are varied but are generally reserved for pregnancies occurring in which the couples are at higher risk for genetic disorders. Discuss these issues with your physician.

Risk Factors:

• The mother is 35 years or older
• There is history of a prior child with a genetic abnormality (e.g. Down’s syndrome)
• There is history of both parents being “carriers” of the same gene for an inheritable disorder
• The mother has a history of 3 or more spontaneous miscarriages
• There is a family history of a known sex-linked disorder (hemophilia, etc.)
• One parent has a history for an unusual chromosomal (genetic) abnormality (translocation)

Remember...

• Risks of amniocentesis are low, however, there is a slight risk of triggering a miscarriage
• There is a very small chance of introducing infection or injury to the fetus
• The sex of the child can be determined by this procedure

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