Increased Intrauterine Transfusion Blood Volume Needed to Correct Fetal Anemia due to Placental Chorioangioma.

Introduction: To compare the blood volume transfused for fetal anemia in cases of placental chorioangioma versus red blood cell (RBC) alloimmunization in patients matched for gestational age (GA) and hydrops.

Methods: Study patients had intrauterine transfusions and were obtained from 3 sources: group (1) placental chorioangioma patients treated at our center (2016-2023); group (2) placental chorioangioma patients reported in the medical literature; and group (3) RBC alloimmunization patients treated for fetal anemia at our center (2016-2023) matched (2:1) to patients in groups 1 and 2 by GA at procedure and presence of hydrops. The expected volume (cc) of transfusion was calculated for all patients based on a formula commonly used for fetal anemia in cases of RBC alloimmunization that includes the GA at procedure, pre-transfusion hemoglobin, donor hemoglobin, and target hemoglobin. The ratio of the volume actually transfused to the expected volume was calculated for each group and for groups 1 and 2 combined; comparisons were made using nonparametric testing.

Results: By group, the patients studied included: (1) 7 treated chorioangioma patients, (2) 8 chorioangioma patients described in the literature, and (3) 30 matched RBC alloimmunization patients. The median (range) GA at procedure for groups 1, 2, and 3 was 29.6 (22.7-32.7), 27.0 (24.0-30.0), 28.4 (22.7-34.3) weeks. The median pre-procedure hemoglobin for each group was 8.5 (5.8-12.5), 6.7 (5.6-12.0), and 5.3 (2.2-10.7) g/dL, and the median post-procedure hemoglobin for each group was 12.9 (11.5-14.0), 12.7 (9.6-14.7), and 13.6 (8.0-15.7) g/dL. The median (range) ratio of the actual to the expected volume transfused for each group was 2.50 (1.79-8.33), 1.64 (1.11-3.85), and 1.10 (0.69-1.86) (p < 0.001). When groups 1 and 2 were combined, the median ratio was 1.89 (1.11-8.33), which remained statistically significant when compared to group 3 (p < 0.001).

Conclusion: Intrauterine transfusion for fetal anemia in cases of large placental chorioangiomas appeared to require nearly twice the blood volume that was normally anticipated for cases of RBC alloimmunization, although the actual amount transfused varied widely.