An easy-to-use method for detecting fetal hemoglobin--a test to identify bleeding from vasa previa.

BACKGROUND Vasa previa is a rare but potentially dangerous fetal condition that may occur during pregnancy. Ideally, all cases such cases are detected antenatally, but many present as late vaginal hemorrhaging. At the current time, there is no test for fetal hemoglobin (HbF) in general use. METHODS A modified method of identifying HbF is presented. Five milliliters of 0.14 M NaOH was combined with 50 microl of a mixture of fetal and maternal blood. After 2 min, it was judged if the solution still had a red tone or not. The sensitivity of this method for detecting HbF was assessed. RESULTS All 15 clinical personnel could identify both 69% and 34% HbF mixed with adult hemoglobin (100% sensitivity), 14 out of 15 could identify 17% HbF (93% sensitivity), and 12 out of 15 could identify a mixture containing 8% HbF (80% sensitivity). CONCLUSION Our rapid, simple test for HbF was at least as sensitive as slower, more cumbersome alkali denaturation tests in common use. It could prove to be a lifesaving tool in ruling out vasa previa bleeding in cases of unclear late pregnancy hemorrhages.