Association of immune-inflammatory indices with focal adenomyosis of the outer myometrium in deep infiltrating endometriosis.

Deep infiltrating endometriosis (DIE) and focal adenomyosis of the outer myometrium (FAOM) are closely related chronic inflammatory conditions that often coexist. The systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and pan-immune-inflammation value (PIV) are novel inflammatory indices derived from peripheral blood cell counts. This study investigates the association between these indices and FAOM in patients with DIE. A retrospective analysis was conducted on 300 patients with pathologically confirmed DIE, comprising 158 patients with FAOM and 142 without. Preoperative peripheral blood counts were collected to calculate SII, SIRI, and PIV levels. After adjusting for all potential confounding factors, multivariate logistic regression analysis showed that SII, SIRI, and PIV were significantly positively associated with FAOM (P < 0.05). Restricted cubic spline (RCS) analysis indicated a significant nonlinear relationship between PIV and FAOM (P for nonlinear < 0.01). Receiver operating characteristic (ROC) curve analysis revealed that the combination of SII, SIRI, and PIV demonstrated the highest diagnostic efficacy for FAOM, with an area under the curve (AUC) of 0.757, a sensitivity of 62.0%, and a specificity of 81.0%. This study demonstrates that elevated levels of SII, SIRI, and PIV in patients with DIE are significantly associated with FAOM. These findings suggest that the aforementioned inflammatory indices can provide valuable supplementary information for the clinical assessment of whether patients with DIE have concomitant FAOM, particularly when MRI or other imaging results are inconclusive. Large-scale, multicenter prospective studies are needed to validate these results and further investigate the underlying biological mechanisms.