Development and validation of a risk prediction model for postpartum urinary incontinence in primiparas using clinical and pelvic floor ultrasound characteristics.

Objective: To develop and validate a nomogram prediction model for postpartum stress urinary incontinence (SUI) in primiparous women, and to evaluate its clinical predictive performance. Methods: This retrospective study enrolled 447 primiparous women who delivered at Zhejiang Hospital and completed follow-up at 6-8 weeks postpartum between July 2022 and January 2024. Clinical characteristics and three-dimensional pelvic floor ultrasound parameters were collected. Participants were randomly assigned to a training set ( Results: Operative vaginal delivery, bladder neck position during maximal Valsalva, urethral rotation angle, retrovesical angle during Valsalva, and levator hiatus area were identified as independent predictors of postpartum SUI. The nomogram demonstrated excellent discriminative ability, with an area under the curve (AUC) of 0.93 (95% CI: 0.91-0.96) in both the training and testing cohorts. Calibration curves showed strong concordance between predicted and observed outcomes. Decision curve analysis further confirmed the clinical utility of the model. Conclusion: The nomogram, which integrates clinical and sonographic variables, shows promising potential as an individualized tool for predicting the risk of postpartum stress urinary incontinence in primiparous women, thereby supporting early screening and timely intervention.