Lower Urinary Tract Symptoms in Women with Surgically Confirmed Endometriosis: Association with Urethral Ultrasonographic Findings

Background: Endometriosis is a chronic inflammatory disease affecting approximately 10% of women of reproductive age and is commonly associated with pelvic pain and infertility. Increasing evidence indicates that lower urinary tract symptoms (LUTS) are more common in women with endometriosis, even in the absence of direct urinary tract involvement; however, the underlying mechanisms remain poorly understood. This study aimed to compare LUTS in women with surgically confirmed endometriosis and symptomatic women in whom endometriosis was surgically excluded, and to investigate their association with urethral ultrasonographic parameters and lesion localization. Methods: This prospective case–control study included 163 women: 81 with surgically confirmed endometriosis and 82 symptomatic controls in whom endometriosis was surgically excluded. Urinary symptoms were assessed using the validated Urogenital Distress Inventory Short Form (UDI-6). Urethral length and mobility were evaluated by transvaginal pelvic floor ultrasonography at rest, during pelvic floor muscle contraction, and during the Valsalva maneuver. Associations between urinary symptoms, ultrasonographic findings, lesion localization, and selected clinical variables were analyzed using appropriate non-parametric tests and multivariable linear regression. Results: Women with endometriosis demonstrated significantly higher total UDI-6 scores than symptomatic controls (p = 0.002), indicating a greater burden of lower urinary tract symptoms. Significant differences were observed only for pain/discomfort and post-void urine leakage, whereas the remaining UDI-6 domains did not differ between groups. Overall urethral ultrasonographic parameters were comparable between groups. However, among symptomatic women (UDI-6 ≥ 1), urethral mobility during the Valsalva maneuver was significantly lower in women with endometriosis than in controls (p = 0.041). Endometriosis localization was not associated with urinary symptom severity or urethral ultrasonographic findings. In multivariable analysis, previous cesarean section, but not endometriosis itself, was independently associated with higher UDI-6 scores. Conclusions: Women with surgically confirmed endometriosis experienced a greater burden of lower urinary tract symptoms than symptomatic women without endometriosis, particularly pain/discomfort and post-void urine leakage. These symptoms were not associated with lesion localization or major differences in urethral morphology, indicating that structural urethral abnormalities alone do not explain urinary symptom severity in this population. Routine assessment of urinary symptoms using validated questionnaires may facilitate comprehensive evaluation of women with endometriosis. Further prospective multicenter studies incorporating standardized pain assessment, urodynamic evaluation, and longitudinal follow-up are warranted to better elucidate the mechanisms underlying lower urinary tract symptoms in this population.