Intraoperative color Doppler during manual vacuum aspiration prevents retained products of conception

OBJECTIVE: To investigate whether intraoperative confirmation of the disappearance of uterine cavity blood flow using color Doppler during manual vacuum aspiration (MVA) for missed miscarriage reduces the occurrence of retained products of conception (RPOC). METHODS: We conducted a retrospective cohort study of 202 patients who underwent MVA for missed miscarriage before 12 weeks of gestation at the University of Yamanashi between April 2019 and July 2025. Patients were divided into a flow-confirmation group, in which intraoperative transvaginal ultrasound with color Doppler was used to confirm the disappearance of blood flow, and a non-confirmation group. The primary outcome was the occurrence of RPOC diagnosed by postoperative ultrasound. Patient characteristics and surgical variables were compared between groups. RESULTS: RPOC occurred in 25 of 202 cases (12%). None of the 25 patients in the flow-confirmation group developed RPOC, whereas 14% of the 177 patients in the non-confirmation group did (P = 0.04). The surgeon's years of experience (2.6 ± 1.6 vs 4.9 ± 4.7 years, P = 0.004) and postoperative follow-up duration (1.9 ± 1.0 vs 3.3 ± 4.3 weeks, P = 0.02) were significantly shorter in the flow-confirmation group, but no other significant differences were found in baseline characteristics or surgical variables. CONCLUSION: Intraoperative confirmation of the disappearance of uterine cavity blood flow using color Doppler during MVA is a simple, safe, and effective technique to prevent RPOC. This approach may reduce the need for repeat surgery and postoperative hemorrhage and could be incorporated into standard MVA protocols.