Diagnostic Accuracy of Uroflowmetry for Urethral Strictures in Pediatric Hypospadias: TIP vs. Non-TIP Outcomes.

Abstract

Introduction: To evaluate the diagnostic accuracy of uroflowmetry in detecting pediatric urethral strictures following Tubularized Incised-Plate (TIP) and non-TIP urethroplasty.

Materials and methods: A retrospective cohort study was conducted on children who underwent primary hypospadias repairs from June 2016 to June 2023 at our institution. Patients were categorized into the TIP and the non-TIP groups. Urethral calibration and uroflowmetry were used to evaluate urethral patency following urethroplasty. Data on demographic characteristics, perioperative information, uroflowmetry results, urethral calibration outcomes, and postoperative complications were collected. The relationship between calibration and uroflowmetry and the diagnostic accuracy of uroflowmetry for urethral strictures were analyzed.

Results: A total of 62 cases were included, with 38 in the TIP group and 24 in the non-TIP group. Ten patients were diagnosed with urethral strictures. The maximum urinary flow rate (Qmax) exhibited a higher area under the curve (AUC) than the average urinary flow rate (Qave) in both the TIP and non-TIP groups. The Qmax in the non-TIP group demonstrated a higher AUC than in the TIP group (non-TIP: AUC=0.94, Cut-off=6.65 ml/s, sensitivity=100%, specificity=81.0%; TIP: AUC=0.80, Cut-off=5.75 ml/s, sensitivity=100%, specificity=58.1%). A significant quadratic correlation was found between Qmax and urethral calibration (non-TIP: C2=14.72*Qmax, R2=0.96; TIP: C2=14.76*Qmax, R2=0.88). The Qmax nomogram interval ≤ -3 standard deviation was a significant predictor for non-TIP urethral strictures (Kappa=0.70).

Conclusions: Uroflowmetry, particularly Qmax, shows promise as a non-invasive screening tool for detecting urethral strictures after hypospadias repair, with high diagnostic accuracy in non-TIP cases but limited utility in TIP cases.