Abstract
BACKGROUND: Mullerian anomalies are frequently associated with endometriosis, particularly in the presence of genital tract obstruction; however, the anatomical distribution and determinants of disease in this population remain incompletely characterized. Most existing data are derived from surgical series, with limited use of standardized imaging-based classification systems. AIM: To characterize the prevalence and distribution of endometriosis in patients with Mullerian anomalies using pelvic magnetic resonance imaging (MRI) and the Enzian classification. METHODS: This retrospective observational study included pelvic MRI examinations performed over a 15-month period. Patients whose MRI reports described Mullerian anomalies were identified, and imaging datasets were re-evaluated. Mullerian anomalies were classified using the Society of Human Reproduction and Embryology/European Society for Gynaecological Endoscopy system. Endometriosis was assessed on MRI and mapped using the Enzian classification, including ovarian (O), peritoneal (P), and deep infiltrating tissue (T) involvement across pelvic compartments. The presence of genital tract obstruction was determined based on MRI evidence of hemorrhagic collections. RESULTS: Seventy-five patients with Mullerian anomalies were included. MRI findings consistent with endometriosis were identified in 22 patients (29.3%). Ovarian endometriomas were the most common manifestation, present in 16 patients (21.3%), while tubo-ovarian involvement corresponding to Enzian T2-T3 disease was seen in 11 patients (14.7%). Endometriosis was more frequently observed in complex uterine configurations, particularly bicorporeal septate uterus (U3c), aplastic uterus with a functional rudimentary cavity (U5a), and in patients classified as U0 with associated cervicovaginal anomalies. Vaginal aplasia (V4) was associated with a significantly lower prevalence of endometriosis compared with normal vaginal anatomy (P = 0.019). Genital tract obstruction showed a strong association with endometriosis, with affected patients demonstrating nearly threefold higher prevalence compared with non-obstructive anomalies (61.5% vs 22.6%, P = 0.005). CONCLUSION: Endometriosis in patients with Mullerian anomalies demonstrates variable distribution on MRI, with higher prevalence in complex and obstructive uterine configurations. MRI combined with standardized Society of Human Reproduction and Embryology/European Society for Gynaecological Endoscopy and Enzian classifications provides a structured, anatomy-driven approach for evaluating disease patterns in this heterogeneous population.