Polymerase chain reaction (PCR) for Toxoplasma gondii DNA
This test is used to diagnose Toxoplasma gondii infection in the fetus. T. gondii is a parasite that can infect humans, but infections often don't cause any symptoms. People can become infected with this parasite after eating infected undercooked meat, especially pork and lamb, or drinking contaminated water. People can also be exposed to the parasite by handling cat feces.
This disease is of particular concern to pregnant women. If a woman becomes infected with the parasite for the first time while she is pregnant, the infection can travel to the fetus. This can lead to birth defects such as brain damage and serious eye problems. Children who appear unaffected at birth may still develop problems later in life. Women who are infected before they become pregnant only rarely pass the disease to their unborn babies.
The test involves sticking a needle through a pregnant woman's abdomen, or belly, into the uterus, and taking out some of the fluid surrounding the fetus. This fluid is called amniotic fluid.
You might have this test if you're pregnant and your health care provider strongly suspects that you have a new T. gondii infection. The results can help guide treatments that may help keep your baby from having medical problems.
Your health care provider may want to test you for antibodies called IgM and IgG, which your immune system makes against this parasite. These can help find out whether you have been infected during pregnancy. Your blood may also be tested to look for this infection.
The provider may also want to examine the fetus with a CT scan or ultrasound.
A result for a lab test may be affected by many things, including the method the laboratory uses to do the test. If your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
If your results are negative, you and your fetus don't have an infection. A positive result means that you and your fetus have T. gondii.
This test requires taking a sample of the amniotic fluid that surrounds the fetus by doing an amniocentesis. Using ultrasound as a guide, your health care provider will put a long needle into your abdomen and into the uterus.
Risks from the amniocentesis procedure include:
Cramping and discomfort
Vaginal bleeding in the mother
Leakage of amniotic fluid afterward
Miscarriage, which occurs in about one in every 300 to 500 procedures
Also, if you have hepatitis, HIV, or another chronic infection, it may infect the fetus.
The PCR test is not able to find T. gondii DNA in amniotic fluid if you develop antibodies against the parasite during your first trimester.
Ask your health care provider whether you should take any special steps to prepare for this test.