Transvaginal ultrasound assessment of ovarian and deep endometriosis using the #Enzian classification: Distribution, laterality, and risk of pouch of Douglas obliteration

OBJECTIVE: To describe the anatomical distribution and laterality patterns of ovarian endometriosis (OE) and deep endometriosis (DE) using TVS and the #Enzian classification, and to evaluate the association between lesion location and the clinical symptoms. METHODS: Retrospective analysis of 394 consecutive women evaluated for suspected endometriosis at a specialized center. All underwent TVS by a single expert operator following the International Deep Endometriosis Analysis (IDEA) consensus protocol. Lesion distribution was classified using the #Enzian system. Poisson regression with robust variance was used to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs). RESULTS: DE was identified in 33.5% of patients and OE in 35.8%. The most frequently affected deep compartment was the uterosacral ligament or pelvic sidewall (B compartment; 52.9%), followed by rectal involvement (C compartment; 31.0%). Laterality differed significantly among compartments: tubo-ovarian adhesions were predominantly bilateral (63.1%), uterosacral ligament lesions were predominantly unilateral (bilateral in only 7.9%), and OE showed an intermediate pattern (38.6%). Rectouterine pouch obliteration was strongly associated with combined OE and DE (PR, 9.14; 95% CI, 5.83-14.35). Symptoms were generally not predictive of lesion location, except for an inverse association between heavy menstrual bleeding and OE (PR, 0.57; 95% CI, 0.38-0.85). CONCLUSION: TVS with the #Enzian classification reveals distinct anatomical and laterality patterns among pelvic compartments. The strong association between combined OE and DE and rectouterine pouch obliteration supports systematic and comprehensive ultrasound evaluation (including the sliding sign) whenever an endometrioma is detected, as it may signal more advanced and surgically complex disease.