OBJECTIVE:To describe fetomaternal hemorrhage (FMH) during second-trimester dilation and evacuation (D&E) to evaluate if Rhesus-immune globulin (RhIG) 100 mcg (used in the United Kingdom) and 300 mcg (used in the United States) provide adequate prophylaxis. STUDY DESIGN:We conducted an exploratory prospective descriptive study of women undergoing D&E between 15 weeks 0 days and 23 weeks 6 days of gestation. Enrolled participants had Kleihauer-Betke testing on specimens obtained before and after D&E. We assessed the main outcome measures of FMH in mL suggesting need for more than 100 mcg and 300 mcg RhIG (FMH of 10 mL and 30 mL fetal whole blood, respectively) and association of postprocedure FMH with demographic characteristics and procedure-related variables. RESULTS:The 300 participants had a mean gestational age of 19 weeks 6 days±2 weeks 2 days. The median preprocedure FMH was 0 mL (range 0-50 mL) with 2 (0.67%) women exceeding 10 mL (19 mL and 50 mL). The median postprocedure FMH was 1 mL (range 0-60 mL). Almost all participants had postprocedure FMH <10 mL (n=295, 98.3%) and <30 mL (n=298, 99.3%). All participants under 18 weeks had FMH <10 mL. We found no demographic or procedure-related factors to be predictive of FMH quantity. CONCLUSIONS:FMH occurring with routine second-trimester D&E procedures is minimal. Adequate prophylaxis with RhIG 100 mcg and 300 mcg occurred in >98% of women and in all cases <18 weeks of gestation. This study is the first step to potentially reducing the dose and costs of RhIG administration with D&E. IMPLICATIONS:This study is a first step in quantifying fetomaternal hemorrhage with routine dilation and evacuation procedures; larger trials are needed, especially to understand why some women have recognizable hemorrhage preprocedure. If dosing requirements are too high with current guidelines, lower doses will result in resource and cost savings.