Uterine-cavity Lactobacillus relative abundance and endometrial polyp recurrence after hysteroscopic polypectomy: a retrospective cohort study

BackgroundEndometrial polyps are among the most common benign uterine lesions, yet their recurrence after hysteroscopic polypectomy remains poorly understood. Emerging evidence suggests that uterine-cavity microbial composition may be related to endometrial inflammation and tissue biology. However, the association between uterine microbiome composition and polyp recurrence has not been systematically investigated.MethodsWe conducted a single-center retrospective cohort study of 288 women who underwent hysteroscopic polypectomy between January 2021 and June 2024. Uterine cavity fluid was collected intraoperatively for 16S rRNA amplicon sequencing (V3–V4 region). Patients were classified into Lactobacillus-Dominant (LD, n = 156) and Lactobacillus-Non-Dominant (LND, n = 132) groups based on Lactobacillus relative abundance ≥70%. The primary outcome was endometrial polyp recurrence confirmed by hysteroscopy at 12 months. Multivariable Cox proportional hazards regression identified independent predictors of recurrence.ResultsThe 12-month recurrence rate was higher in the LND group than in the LD group (31.8% vs. 14.1%, p < 0.001). LND samples had higher relative abundances of Gardnerella (15.3%), Prevotella (12.1%), and Streptococcus (8.7%), higher Shannon diversity (3.87 ± 0.98 vs. 1.34 ± 0.52, p < 0.001), and higher serum IL-6 and CRP levels. In the multivariable Cox model, LND status remained associated with recurrence (adjusted HR 2.41; 95% CI 1.48–3.93; p = 0.001). BMI ≥ 28 kg/m2, polyp size ≥15 mm, multiplicity, and postoperative hormonal therapy were also associated with recurrence; the hormonal-therapy estimate indicated lower recurrence (adjusted HR 0.48). These estimates are observational and may be affected by residual confounding.ConclusionLactobacillus-non-dominant uterine-cavity microbiome status was associated with higher 12-month endometrial polyp recurrence after hysteroscopic polypectomy after adjustment for measured clinical factors. These findings support further evaluation of uterine microbiome profiles as potential risk-stratification markers, but they do not establish causality or justify routine antimicrobial or microbiome-guided treatment.