Risk factors of retained products of conception after miscarriage or termination with gemeprost in the second trimester of pregnancy: a retrospective case-controlled study in Japanese population

Retained products of conception (RPOC) is a complication that occurs in the second trimester of pregnancy. We enrolled 98 women who had a miscarriage or termination with gemeprost in the second trimester of pregnancy. Eighteen cases (18.4%) were RPOC-positive. The gestational week at miscarriage or termination was earlier in the RPOC-positive group than those in the RPOC-negative group (p = .003). The period of the third stage of labour was longer in the RPOC-positive group than in RPOC-negative group (p = .040). The proportion of placental forceps use was higher in the RPOC-positive group than in RPOC-negative group (p = .003). Multivariate logistic regression analysis showed that gestational week (OR: 3.53; p = .04) and use of placental forceps at delivery (OR: 2.21; p = .012) were independent risk factors for RPOC. Earlier gestational weeks at miscarriage or termination and use of placental forceps at delivery were predictive factors for RPOC after second trimester miscarriage or termination with gemeprost.Impact Statement What is already known on this subject? There have been some reports on risk factors of RPOC. A previous report showed that the termination of pregnancy with misoprostol at earlier periods was associated with an increased risk of RPOC. What the results of this study add? There have been few studies on the risk factors of RPOC after miscarriage or termination with gemeprost. In this study, we evaluated the risk factors of RPOC after miscarriage or termination of pregnancy with gemeprost in the second trimester. We found that an earlier gestational age (between 12 and 17 weeks) at delivery and using placental forceps to remove placenta were significant risk factors of RPOC after miscarriage or termination of pregnancy with gemeprost in the second trimester. What the implications are of these findings for clinical practice and/or further research? An earlier gestational age and using forceps to remove placenta may be significant risk factors for RPOC. The accurate evaluation and treatment for RPOC is important for maternal life-saving efforts and subsequent pregnancies. Further research is needed to draft a standardised protocol for RPOC.