Massive antenatal fetomaternal hemorrhage: evidence for long-term survival of fetal red blood cells.

BACKGROUND: Massive fetomaternal hemorrhage (FMH) can lead to life-threatening anemia. Quantification based on flow cytometry with anti-hemoglobin F (HbF) is applicable in all cases but underestimation of large fetal bleeds has been reported. A large FMH from an ABO-compatible fetus allows an estimation of the life span of fetal red blood cells (RBCs) in the maternal circulation. CASE REPORT: The mother went to the obstetrician twice antepartum owing to symptoms assumed to be preeclampsia; that, however, was not found. She later delivered by cesarean section owing to diminished fetal movements. No fetal weight gain was observed during the last 2 weeks of pregnancy. STUDY DESIGN AND METHODS: Fetal RBCs were quantified by flow cytometry with anti-HbF, anti-Fya, anti-s, and anti-Jkb on a regular basis. RESULTS: The infant had anemia at delivery and an FMH was determined to be 314 ± 17 mL (± SD) of whole blood. It is assumed that the two antenatal visits were associated with the FMH. Postpartum follow-up showed that fetal RBCs in the maternal circulation were detectable with anti-HbF up to 119 days. Quantification by flow cytometry based on anti-HbF was in agreement with quantification based on anti-Fya, anti-s, and anti-Jkb, although they were less sensitive. CONCLUSION: ABO-compatible fetal RBCs from an FMH had a life span in the maternal circulation close to that of adult RBCs.