Treatment of fetal anemia due to red-cell alloimmunization with intrauterine transfusions in the Netherlands, 1988-1999.

OBJECTIVE: To assess pregnancy outcome after intrauterine transfusion (IUT) for fetal anemia due to red-cell alloimmunization in the Netherlands over 11 years, in order to improve care and counseling.

METHODS: A retrospective cohort study was conducted from January 1, 1988, to January 1, 1999. Data were collected prospectively on all red-cell alloimmunized pregnancies requiring intrauterine blood transfusions. Primary outcome variables were fetal and neonatal survival in relation to the type of antibody, gestational age and presence or absence of hydrops. In addition, we studied short-term neonatal morbidity and procedure-related complications.

RESULTS: A total of 210 fetuses from 208 pregnancies received 593 transfusions. Overall survival rate was 86%. Survival of hydropic fetuses (78%) was significantly different from those without hydrops (92%). Low survival rates were especially found in hydropic fetuses with the first transfusion at gestational ages of 20 weeks or less (55%) or between 28 and 32 weeks (59%). In maternal rhesus D [Rh(D)] immunization 89% of fetuses survived, whereas survival in the case of Kell immunization was 58%. All fetuses with anemia due to Rh(c) immunization survived. The overall fatal procedure-related complication rate was 1.7% per procedure, resulting in a fetal loss rate of 4.8%.

CONCLUSIONS: Intrauterine intravascular transfusions are effective in the management of fetal alloimmune anemia. Fetal hydrops, mostly associated with late referral, decreases the chance of survival. To improve the outcome of red-cell alloimmunized pregnancies early diagnosis of fetal anemia and referral to a specialized center are important, enabling the start of treatment before hydrops develops.