Antibiotics improve reproductive outcomes after frozen-thaw embryo transfer for chronic endometritis treatment, especially in those with repeated implantation failure

To investigate the impact of antibiotic treatment for chronic endometritis (CE) on the pregnancy outcome of frozen-thawed embryo transfer (FET) cycles and the relevant clinical risk factors associated with CE. A retrospective cohort analysis was conducted on 1352 patients who underwent hysteroscopy and diagnostic curettage at Nanjing Maternal and Child Health Hospital from July 2020 to December 2021. All patients underwent CD138 immunohistochemical (IHC) testing to diagnose CE, and a subset of them underwent FET after hysteroscopy. Patient histories were collected, and reproductive prognosis was followed up. Out of 1088 patients, 443 (40.7%) were diagnosed with CE. Univariate and multivariate binary logistic regression analyses revealed that parity ≥ 2, a history of ectopic pregnancy, moderate-to-severe dysmenorrhea, hydrosalpinx, endometrial polyps, a history of ≥ 2 uterine operations, and RIF were significantly associated with an elevated risk of CE (P 0.05). Infertile patients with a history of parity ≥ 2, hydrosalpinx, a history of ectopic pregnancy, moderate-to-severe dysmenorrhea, endometrial polyps, a history of ≥ 2 uterine operations, and RIF are at an increased risk of CE; these patients should be recommended to undergo hysteroscopy combined with CD138 examination before embryo transfer. Antibiotic treatment can improve the reproductive outcomes of FET in patients with CE, especially those with RIF.