P-348 Correlation between cesarean scar defect and chronic endometritis and its effect on the pregnancy outcomes of in vitro fertilization

Abstract Study question Do patients with symptomatic cesarean scar defect (CSD) have a higher risk of chronic endometritis (CE) and worse early pregnancy outcomes after hysteroscopic reconstruction for CSD? Summary answer Symptomatic CSD has a positive correlation with CE. Antibiotic administration is a promising option for patients with CE to obtain better early pregnancy outcomes. What is known already Cesarean scar defect (CSD), a niche-shaped myometrium defect, can be noticed after cesarean sections (CS). Studies about the impact of CSD on fertility are limited. The uterine isthmic region is a sperm reservoir, and CSD may negatively affect natural fertility. CE could reduce endometrial receptivity and thus leads to a lower clinical pregnancy rate. Secondary infertile patients with a history of CS are quite common in the department of reproductive medicine. However, there was still limited data to determine whether CSD correlates with CE, especially in cases suffering from symptomatic CSD with postmenstrual spotting. Study design, size, duration This is a retrospective study including 118 patients with a leading symptom of postmenstrual spotting and 224 asymptomatic patients from January 1, 2018 to May 31, 2021. Participants/materials, setting, methods Group A was with a leading symptom of postmenstrual spotting, and group B was asymptomatic. Office operative hysteroscopy was performed to correct the CSD for symptomatic patients in group A, and thermoablation of the endometrium in CSD was performed. Out-patient hysteroscopy was performed for asymptomatic patients in group B, and only the morphology of the endometrium was evaluated. Both groups have CD138 immunohistochemistry staining of their endometrium. Main results and the role of chance A higher incidence of CE was found in group A compared with group B (50/118 vs. 62/224, P=0.006, OR = 1.921, 95%CI=1.203-3.068). There were no significant differences in the comparisons of chemical pregnancy rate (26/86 vs. 75/216, P=0.455, OR = 0.815, 95%CI=0.475-1.396), ectopic pregnancy rate (1/86 vs. 1/216, P=0.489, OR = 2.529, 95%CI=0.156-40.901), miscarriage rate (6/86 vs. 22/216, P=0.368, OR = 0.661, 95%CI=0.258-1.692), preterm birth rate (2/86 vs. 4/216, P=1.000, OR = 1.262, 95%CI=0.227-7.020) or full-term pregnancy rate (12/86 vs. 35/216, P=0.626, OR = 0.839, 95%CI=0.413-1.704) between the two groups. Limitations, reasons for caution First, different doctors might have inconsistent judgments on the definition of postmenstrual spotting. Second, three different operators performed the hysteroscopy. It might contribute to the heterogeneity of the study findings. Wider implications of the findings Canalling and thermoablation during hysteroscopy are effective treatments for symptomatic CSD. CSD accompanied by CE should be given more attention before embryo transfer. Trial registration number No. 2020A1515110791