Prenatal screening for toxoplasmosis.

OBJECTIVE

To evaluate the merits of screening for toxoplasmosis in all pregnant women.

METHODS

We used decision analysis to compare three strategies for the antepartum management of congenital toxoplasmosis: 1) no testing for congenital toxoplasmosis; 2) current practice, which is to perform targeted screening in cases of incidental abnormalities noted on ultrasound; and 3) universal serologic screening of pregnant women followed by amniocentesis to diagnose fetal infection in cases of maternal seroconversion. For each of the three strategies, we considered the two available treatment options: intrauterine antiparasitic treatment or pregnancy termination.

RESULTS

Universal screening reduced the total number of cases of congenital toxoplasmosis compared with no testing or targeted screening. However, compared with no testing, universal screening with medical treatment resulted in 18.5 additional pregnancy losses for each case of toxoplasmosis avoided. If infected pregnancies underwent termination, universal screening resulted in 12.1 additional pregnancy losses for each case avoided.

CONCLUSION

Maternal screening reduces the number of cases of disease, but at a substantial clinical cost. The rarity of the disease and limitations in diagnosis and therapy limit the effectiveness of screening strategies. The risks associated with amniocentesis are particularly important. Universal maternal screening for congenital toxoplasmosis should not be performed.