There are two types of tests that can be performed on amniotic fluid to show different types of problems with the fetus:
- Genetic amniocentesis
- Chemical tests
The cells in the amniotic fluid contain genetic material that can be used to observe chromosomal abnormalities or defects in specific genes. Biochemical substances, like proteins and lipids, can give clues about the health or maturity of the fetus.
The need for genetic testing of amniotic fluid depends on:
- The age of the parents
- Family history of genetic abnormalities
- Problems found during blood tests on the mother
- Ultrasound results
For genetic testing, fetal cells collected by amniocentesis, isolated, and allowed to grow in the laboratory and divide. The
A commonly detected abnormality is
Sex chromosome abnormalities can also be detected. Some, like
The chromosome test can also reveal the sex of the fetus, since males have an X and a Y chromosome, while females have two X chromosomes.
Many other tests can also be performed on amniotic fluid. A test for the presence of
Other diseases, such as
When a mother is Rh negative, meaning her red blood cells lack a specific protein on their surface, amniocentesis can reveal if the fetus is Rh positive. The resulting fetal anemia from destruction of red blood cells in Rh immunization disease can also be detected from levels of bilirubin in amniotic fluid.
Nice to Know:
85 percent of people are Rh positive. If the mother is Rh negative and the father is Rh positive, there is a chance of having an Rh positive baby.
In the second and third trimesters, analyzing the amniotic fluid can help show how mature the fetal lungs are by measuring the fetal lung lipid (surfactant) in the fluid. This can help prevent a premature delivery. In a pregnancy complicated by diabetes, monitoring the levels of glucose and insulin in amniotic fluid can be helpful. In cases of preterm labor or preterm ruptured membranes, checking for the presence of bacteria in the amniotic fluid is an important diagnostic test.
For more detailed information about preterm labor, go to Premature Labor.