Prenatal eradication of Hb Bart's hydrops fetalis

OBJECTIVE: To evaluate the effectiveness of prenatal prevention of Hb Bart' s hydrops fetalis. STUDY DESIGN: The study was a prospective descriptive analysis of pregnant women attending an antenatal clinic between June 1990 and June 1998. The st udy consisted of two periods, the first half with no prenatal diagnosis (PN D) (1990-1994) and the second half with PND. During the study period, all c ases of Hb Bart's hydrops fetalis were prospectively collected and postnata lly confirmed. In the second period, prenatal strategy to control severe th alassemia was introduced. The strategy included (1) carrier identification by retrospective (history review for known risk) and prospective screening (simple erythrocyte osmotic fragility test) in women without known risks, ( 2) the couples at risk were offered genetic counseling and cordocentesis, ( 3) analysis of fetal blood for diagnosis, and (4) counseling for terminatio n of pregnancy. RESULTS: During the first half of the study, the prevalence of Hb Bart's hy drops was 0.30% (89 in 29,399 deliveries). There were no fetuses with Hb Ba rt's hydrops fetalis among 16,360 screened pregnancies in the second half. However, of 6,856 pregnancies in the second half not screened due to a late first visit, 10 (0.15%) fetuses had Hb Bart's hydrops fetalis. Among the s creened group, cordocentesis was performed in 361 pregnancies at risk, 170 and 191 from retrospective and prospective screening, respectively; and 75 (20.8%) were proven to have Hb Bart's disease, which was diagnosed before h ydropic changes occurred. CONCLUSION: The strategy proved effective in preventing Hb Bart's hydrops f etalis, and extensive experience with it suggests that it be considered an effective way to control severe thalassemia.