Determinant Factors From Transvaginal Ultrasonography for the Intervention of Retained Products of Conception: A Retrospective Analysis of 61 Cases.

OBJECTIVE: This study aimed to retrospectively analyze the determining factors for intervention in patients with retained products of conception (RPOC). METHODS: We included 61 patients diagnosed with RPOC at our institute from January 2018 to May 2024. Interventions were performed for postpartum hemorrhage in 18 patients (intervention group), while the remaining 43 patients were observed until spontaneous resolution occurred (non-intervention group). The maximal dimension of RPOC (size) and blood flow were assessed using transvaginal ultrasonography before the intervention (median, 23.5 days postpartum) in the intervention group and at the 1-month check-up in the non-intervention group. Color Doppler profiles were evaluated for the degree of vascularity using the Gutenberg classification (types 0 to 3). A logistic regression analysis was used to compare the background and ultrasonographic findings of the maximal dimension of RPOC and Gutenberg classification with the requirement for intervention. RESULTS: The multivariate analysis showed significant differences in the maximal dimension of RPOC (P=0.002) and the Gutenberg classification (P=0.005). The receiver operating characteristics curve for predicting the requirement for intervention, based on the maximal dimension of RPOC and the Gutenberg classification, showed a cut-off of 41 mm and type 1, with areas under the curve of 0.86 (95% confidence interval, 0.75-0.98) and 0.80 (0.69-0.90), respectively. Using a simple prediction model (the maximal dimension of RPOC [mm]×0.1+ [Gutenberg classification] ×2) with a cut-off value of 7.3, the prediction showed a higher area under the curve (0.94, 0.89-0.99) than individual parameters. CONCLUSION: The combination of the maximal dimension of RPOC and the blood flow profile according to the Gutenberg classification effectively predicts the requirement for intervention.