At a Glance
Why Get Tested?
To detect and diagnose certain birth defects, genetic diseases, and chromosomal abnormalities in a fetus, especially if maternal serum screening tests are abnormal; to evaluate fetal lung maturity when there is an increased risk of premature delivery; sometimes to diagnose a fetal infection; occasionally to help diagnose and monitor hemolytic disease in a fetus
When to Get Tested?
Between 15 and 20 weeks of gestation to test for genetic diseases, chromosomal abnormalities, and open neural tube defects; after 32 weeks to evaluate fetal lung maturity; when it is suspected that a fetus has an infection or other illness; serially, about every 14 days, when it is suspected that a pregnant woman has an Rh or other blood type incompatibility with her fetus
Test Preparation Needed?
You may be instructed to have either a full or empty bladder prior to amniocentesis, depending on when during your pregnancy the testing is being performed; follow any instructions you are given.