Massive fetomaternal hemorrhage and successful prevention of maternal RhD alloimmunization: A case report.

BACKGROUND: Massive fetomaternal hemorrhage can lead to significant fetal morbidity or mortality. RhD negative patients require appropriate treatment to prevent alloimmunization in subsequent pregnancies. Few cases with follow-up into future pregnancies have been reported. CASE REPORT AND RESULTS: 30-year-old gravida 3 para 1 presented at 40 weeks and 2 days gestation for late term evaluation. Ultrasonography identified an intrauterine fetal demise. The patient was O RhD negative and had previously received Rh immunoglobin (RhIG) at 26 weeks of gestation. The patient was induced and delivered a 3,450 gram stillborn fetus. Kleihauer-Betke testing performed and revealed massive fetomaternal hemorrhage with a result of 5.4-6.0%. The calculated fetomaternal hemorrhage was estimated to be 281.6 mL (approaching the total estimated fetal blood volume of 293 mL). The patient received 3 vials of intramuscular RhIG (300 μg/vial), 2 vials of intravenous RhIG (1,000 μg/vial), and 1 vial of intravenous RhIG (300 μg/vial) for a total RhIG dose of 3,200 μg, over a 3-day period, with no adverse clinical sequelae. Serological investigations for anti-D antibodies remained positive until 6 months and were inconclusive at 8 months postpartum. At 10 months postpartum, she was 9 weeks pregnant and no anti-D antibodies were detected. With this subsequent pregnancy, she was treated with routine RhIG and delivered a healthy RhD positive neonate. CONCLUSION: Adequate dosing of RhIG can be achieved to prevent alloimmunization, even in massive fetomaternal hemorrhages. After large doses of RhIG, anti-D antibodies may persist for several months and do not necessarily indicate maternal alloimmunization.