Association between monocyte percentage and chronic endometritis among infertile patients: a retrospective study.

The diagnosis rate of chronic endometritis (CE), closely associated with infertility, recurrent pregnancy loss, and recurrent implantation failure, remains low in clinical practice. The monocyte percentage (MP) has been identified as a biomarker predicting prognosis in various severe diseases. Although monocytes have been linked to clinical endometritis in animals, their associations with CE in infertile patients remains unclear. This cross-sectional study included patients pathologically diagnosed with CE at a single center in 2021. Demographic data, history of abortion, causes of infertility, Ureaplasma urealyticum infection history, laboratory findings, and histological information were recorded. The correlation between MP and CE was investigated using logistic regression analysis, and subgroup analyses were conducted based on age, gravidity, parity, and follicular phase. The cohort consisted of 631 individuals, including 494 patients with CE, corresponding to a CE prevalence of 78%. Univariate logistic regression analysis revealed an inverse correlation between MP and CE risk (odds ratio [OR] = 0.85; 95% confidence interval [CL], 0.76-0.96; P < 0.01). Multivariate regression after adjusting for all covariates yielded an OR of 0.82 (95% CI 0.71-0.95). Furthermore, the stratified and subgroup analyses yielded consistent results. Sensitivity analyses excluding participants with pathological endometrial changes (OR = 0.83; 95% CI 0.71-0.96), those in the non-follicular phase (OR = 0.78; 95% CI 0.66-0.92), and those with both endometrial abnormality and non-follicular phase status (OR = 0.82; 95% CI 0.7-0.95) further confirmed the correlation between MP and CE risk. MP was significantly associated with CE in infertile participants in models adjusted for all covariates, suggesting that MP may be a valuable parameter for early CE prediction.