Toxoplasmosis During Pregnancy: Exams And Tests

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Exams and Tests

In most areas of the United States and Canada, fetal toxoplasmosis infection is rare. In the United States, about 1 to 10 infants per 10,000 actually become infected before birth.³ This is why screening for toxoplasmosis is not a part of routine prenatal care in this country. But getting tested for toxoplasmosis may be a good idea if you are pregnant or planning to become pregnant and:

• You are worried that you might get toxoplasmosis.
• You think you may not be able to avoid exposure to the parasite.

Consider what higher-risk countries recommend as you make your decision about testing:

• In countries where toxoplasmosis risk is moderate, all newborns are screened for toxoplasmosis infection. Some states in the United States now screen all newborns for toxoplasmosis.
• In some countries where toxoplasmosis risk is high, all pregnant women are screened for toxoplasmosis antibodies.

A blood test is used to see whether you have the antibody to the toxoplasma parasite. If you have the antibody, that means you have already been infected, and your immune system now makes antibodies that can fight toxoplasma. These antibodies protect your fetus and newborn from infection.

You may need more than one blood test to make sure the result is accurate.

Tests for toxoplasmosis

• Toxoplasmosis blood test looks for the antibody to toxoplasma. If test results or symptoms show possible infection, another test is done 2 to 3 weeks later to confirm the diagnosis.
• Amniocentesis is used to collect amniotic fluid for testing. A polymerase chain reaction (PCR) test is used on the fluid to check for signs of toxoplasma DNA. This test can detect fetal toxoplasmosis.
• Fetal ultrasound is used to check for signs of toxoplasmosis damage in the fetus.

Early Detection

Birth defects are most likely to develop when a fetus is infected during weeks 10 through 24 of pregnancy.⁴ This is why early detection and treatment of fetal toxoplasmosis is important for preventing severe fetal problems. (If an infection develops later in pregnancy, severe fetal problems are less likely, but treatment is important to prevent future problems.)

Last updated:	June 27, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	Joy Melnikow, MD, MPH - Family Medicine, Gregory A L Davies, MD, FRCSC, FACOG - Maternal-Fetal Medicine
Editors:	Susan Van Houten, RN, BSN, MBA, Pat Truman, MATC