Confirmatory serologic testing for acute toxoplasmosis and rate of inducedabortions among women reported to have positive Toxoplasma immunoglobulin M antibody titers

OBJECTIVE: Results obtained with commercial testing kits for immunoglobulin M Toxoplasma antibodies may be inaccurate or may be inaccurately interpret ed, which may influence whether a woman decides to terminate the pregnancy. This study was undertaken to determine whether confirmatory testing at a r eference laboratory and communication of the results and an expert interpre tation to the patient's physician would affect the rate of induced abortion s among pregnant women with positive results of testing for immunoglobulin M Toxoplasma antibodies in outside laboratories. STUDY DESIGN: This was a retrospective cohort study of 811 consecutive preg nant women for whom the toxoplasma serologic profile was performed at a ref erence laboratory. Almost ail the patients had been informed by their physi cians that a result of a test for immunoglobulin M Toxoplasma antibodies pe rformed in an outside laboratory was positive. Women were separated into th ose with a toxoplasma serologic profile result suggestive of a recently acq uired infection (group 1) and those with a result suggestive of an infectio n acquired in the more distant past (group 2). Physician reports of induced abortions were used to determine rates or induced abortion in groups 1 and 2. RESULTS: Of the 811 women 321 (39.6%) were considered likely to have a rece nt infection (group 1) and 490 (60.4%) were considered likely to have a pas t infection (group 2). Physicians reported pregnancy outcomes for 433 (53.4 %) of 811 women (65.1% and 45.7% in groups 1 and 2, respectively). Whereas 36 of 209 women in group 1 (17.2%) terminated the pregnancy, only 1 of 224 women in group 2 (0.4%) chose abortion (P<.001). CONCLUSION: Confirmatory serologic testing in a reference laboratory and co mmunication of the results and their correct interpretation by an expert to the patient's physician decreased the rate of unnecessary abortions by app roximately 50% among women for whom positive immunoglobulin M Toxoplasma te st results had been reported by outside laboratories.