Associations of Vaginal Pressure and Transversus Abdominis Muscle Thickness with Overactive Bladder in Women: A Cross-Sectional Study

Background and Objectives: Overactive bladder (OAB) has been associated with pelvic floor dysfunction, but the associations of vaginal pressure (VP) and transversus abdominis (TVA) thickness with OAB remain unclear. We examined these associations in women with lower urinary tract symptoms. Materials and Methods: This retrospective cross-sectional study included 213 women; 106 met the prespecified Overactive Bladder Symptom Score criteria and 107 did not. Maximal VP during voluntary pelvic floor contraction and ultrasonographic TVA thickness at rest, during maximal inspiration and maximal expiration, and during the abdominal drawing-in maneuver were compared between groups. Multivariable logistic regression adjusted for age, body mass index, number of deliveries, postmenopausal status, and hypertension. Results: Maximal VP and TVA thickness during the abdominal drawing-in maneuver were lower in the OAB group. In the continuous-variable model, higher VP (per 5-cmH2O increase: OR = 0.704, 95% CI 0.576–0.845) and greater TVA thickness during the abdominal drawing-in maneuver (per 1-mm increase: OR = 0.500, 95% CI 0.343–0.708) were associated with lower odds of OAB. Neither measure showed a consistent stepwise relationship with OAB severity. Exploratory ROC analyses yielded moderate apparent AUCs, but the cohort-derived cutoffs require external validation and should not inform clinical decisions. Conclusions: Lower VP and lower TVA thickness during the abdominal drawing-in maneuver were associated with OAB in this selected cohort. Concurrent cross-sectional assessment cannot establish causality or temporal relationships and cannot exclude reverse causation. Prospective studies are required before considering predictive or preventive roles, and cohort-derived cutoffs require external validation before clinical use.