SEVERE FETOMATERNAL ALLOIMMUNE THROMBOCYTOPENIA PRESENTING WITH FETALHYDROCEPHALUS

We report two patients where the finding of isolated fetal hydrocephal us led to the detection of severe fetal thrombocytopenia, using fetal blood sampling. Serological investigation led to the diagnosis of feto maternal alloimmune thrombocytopenia (FMAIT) due to anti-HPA-la. Both women had had previous unsuccessful pregnancies probably due to FMAIT; one had had four miscarriages at 17-18 weeks' gestation. The other ha d had one previous pregnancy complicated by severe fetal anaemia, and eventually hydrocephalus developed and the fetus died without the diag nosis of FMAIT being considered. Subsequent pregnancies in the two wom en were also affected by FMAIT, but prenatal treatment, predominantly with serial fetal platelet transfusions, resulted in a successful outc ome in both cases. These observations suggest that FMAIT should be sus pected if there is isolated fetal hydrocephalus, unexplained fetal ana emia, or recurrent miscarriages. The accurate diagnosis of FMAIT is im portant because recent advances in prenatal management can improve the outcome of subsequently affected pregnancies.