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

BACKGROUND

Endometrial 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.

METHODS

We 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.

RESULTS

The 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.

CONCLUSION

Lactobacillus-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.