Dual diagnosis of prenatal haemophilia A by measurement of fetal factor VIIIC and VIIIC antigen (VIIICAg)

Abstract

Procoagulant factor VIII (VIIIC) and procoagulant factor VIII antigen (VIIICAg) were measured in 20 samples of pure fetal blood obtained by fetoscopy at mid-term from non-haemophilic fetuses. VIIIC levels ranged from 25 to 89 U/dl (mean 43.5) and VIIICAg from 11 to 43 U/dl (mean 22.3). Samples from 39 consecutive fetuses at risk of haemophilia A gave results indicating haemophilia in 11, and these pregnancies were terminated at the parents' request. Of the remaining 28, 18 have resulted in normal births, 8 still await delivery, and 2 pregnancies were terminated for non-haematological reasons. The results confirm that pure fetal blood can be aspirated fetoscopically for plasma assays of both VIIIC and VIIICAg. Dual measurement enhances the reliability of predicting or excluding haemophilia A, and makes prenatal diagnosis a dependable option for known or potential carriers seeking this information.