P-326 No higher incidence of chronic endometritis in infertile women with polycystic ovary syndrome: a propensity score-matched study

Abstract Study question Do infertile women with polycystic ovary syndrome(PCOS) have a higher incidence of chronic endometritis(CE) and need to screened for CE before assisted reproductive technology(ART)? Summary answer Under the diagnosis by CD138 immunohistochemical staining, no significant difference was found in the comparison of CE incidence between PCOS patients and non-PCOS patients. What is known already PCOS is the most common endocrinopathy among women of reproductive age and causes increased risks of embryo implantation failure and pregnancy loss. The chronic low-grade inflammation of the endometrium in PCOS women should not be ignored. CE is a local inflammation of the endometrium and also harms endometrial receptivity. Some specialists suggest that women at high risk of CE (such as endometrial polyps, repeated implantation failure, etc.) should be screened for CE before before ART. However, the risk of CE under the diagnosis by CD138 immunohistochemical staining for endometrial specimen in PCOS women has not been previously evaluated. Study design, size, duration We conducted a retrospective analysis of all infertile patients undergoing their first hysteroscopic operations during 2017-2022 from one tertiary hospital. All patients underwent hysteroscopy in the proliferative phase and endometrial biopsy for immunohistochemistry staining for CD138 was carried out. Cesarean section, intrauterine adhesion, recurrent spontaneous abortion or recurrent implantation failure and other diseases potentially related to chronic endometritis were strictly excluded. The CE incidence between PCOS patients and non-PCOS patients was compared. Participants/materials, setting, methods Endometrial biopsy and immunohistochemistry staining for CD138 was carried out among all patients. Demographic information were recorded. A propensity score matching (PSM) model was used to match the independent variables to balance the influence of confounding factors. Subgroup analysis according to different body mass index were also taken among PCOS patients and non-PCOS patients. Furthermore, a multivariate logistic model was used to explore the risk factors affecting CE incidence. Main results and the role of chance A total of 205 cases were allocated to the PCOS group, while 4021 cases were allocated to the non-PCOS group in the final analysis. After PSM, 197 PCOS patients were matched with 197 patients in the non-PCOS group. Significant differences were only found in the comparisons of PCOS-associated characteristics (P < 0.05) and the other baseline characteristics of the two groups were not significantly different(P > 0.05). No higher CE incidence in infertile women with PCOS was found either in total analysis or after PSM (P = 0.969, OR 1.01, 95% CI: 0.75-1.36; P = 0.385, OR 1.21, 95% CI: 0.75-1.36; respectively). Similar results were discovered in the subgroup of BMI≥28 kg/m2, BMI 24 -28kg/m2, and BMI＜24 kg/m2 (P = 0.301, OR 1.64, 95% CI: 0.64-4.19; P = 0.671, OR 1.13, 95% CI: 0.65-1.95; P = 0.427, OR 0.85, 95% CI: 0.58-1.27; respectively). Interestingly, a rising trend of CE incidence was found with the BMI increased in the PCOS group, even though no significant differences were found (BMI＜24 kg/m2: 28.80%; BMI 24 -28kg/m2: 36.66%; BMI≥28 kg/m2: 45.00%; respectively). Multivariate logistic regression showed that age, infertility duration, infertility type, PCOS, and obesity were not the independent risk factors affecting CE incidence. Limitations, reasons for caution Information bias cannot be ruled out because of the retrospective design of this study. Hence, we used PSM and regression analysis to minimize the impact of confounding variable. Besides, the sample size of patients with PCOS was limited. Therefore, a larger sample size will be used in our future study. Wider implications of the findings We firstly investigate the relationship between PCOS and CE diagnosed by CD138. The current evidence does not support PCOS women should screened for CE before ART. In the future, a larger sample of studies are needed to investigate the relationship between PCOS and CE, especially for obese PCOS patients. Trial registration number not applicable