High prevalence of chronic endometritis in women with nonstructural abnormal uterine bleeding and benefits of antimicrobial treatment on blood loss pattern: A prospective, observational study

Objective The causal link between chronic endometritis (CE) and nonstructural abnormal uterine bleeding (AUB) has been poorly investigated and requires further clarification. This study aimed to evaluate the prevalence of CE in women with nonstructural AUB and to assess the effect of CE cure on the menstrual blood loss pattern. Methods This prospective study was conducted between 2022 and 2024 at the Department of Obstetrics and Gynecology, University of Bari, Italy. Women aged 20-45 undergoing hysteroscopy for AUB with confirmation of nonstructural causes were evaluated for CE and considered affected when both hysteroscopic and histologic/immunohistochemical (HIS/IHC) criteria were met. Women with CE were treated with specific culture-guided therapy. Cure ascertainment was confirmed by triple negativity at hysteroscopy-HIS/IHC-culture (Group A). In cases of a positive test, a second course of therapy, up to three courses, was repeated before declaring a persistent condition (Group B). At enrollment and at end-of-treatment evaluation, all participants completed a questionnaire to describe the bleeding characteristics and the Pictorial Blood Assessment Chart (PBAC). Serum hemoglobin and ferritin were also assessed. Results Chronic endometritis was diagnosed in 102 of 145 (70.3%) women with nonstructural AUB enrolled in the study. Out of 102 CE patients, 81 (79.4%) patients showed CE resolution after therapy (group A), while in 21 patients (20.6%) CE was persistent (group B). The duration of heavy bleeding before treatment (baseline) was similar in both groups (P = ns). In contrast, at the end of treatment, days of heavy bleeding, days of spotting, and PBAC scores decreased significantly in group A compared with both same-group baseline assessment and group B. Serum hemoglobin and ferritin levels in cured women (A) were significantly higher than in those with persistent CE (B). PBAC scores in group A at 3 and 6 months after the end of treatment showed persistence of cure benefits on AUB. Finally, among patients with CE diagnosis, both univariate and multivariate regressions showed a significant association between cure of CE and reduced bleeding. Conclusion Chronic endometritis was highly prevalent in women with nonstructural AUB in our cohort. Cure of CE by targeted antimicrobial therapy led to significant improvements in bleeding patterns.