Development and Internal Validation of a Nomogram for Delayed Treatment in Pediatric Testicular Torsion: A Retrospective Study Spanning Over Two Decades.

BACKGROUND: Testicular torsion (TT) is a time-sensitive pediatric urologic emergency in which delayed treatment markedly reduces the likelihood of testicular salvage. This study aimed to identify factors associated with delayed treatment in children with TT and to develop and internally validate a nomogram for retrospective characterization of delay-risk profiles. METHODS: A total of 540 pediatric patients with surgically confirmed TT were retrospectively included and randomly assigned to a training cohort (n=377) and a validation cohort (n=163). Least absolute shrinkage and selection operator (LASSO) regression was used for variable selection in the training cohort, followed by multivariable logistic regression to construct the final model and nomogram. Model performance was evaluated by discrimination, calibration, decision curve analysis (DCA), and bootstrap internal validation. RESULTS: Nine predictors were retained for final model development: age, sports or injuries, persistent symptoms, onset during sleep, misdiagnosis, degree of cord twisting > 180°, guardian awareness of TT, transfer distance, and ipsilateral hydrocele. The nomogram showed good discrimination, with an area under the receiver operating characteristic curve (AUC) of 0.952 (95% CI, 0.932-0.973) in the training cohort and 0.940 (95% CI, 0.904-0.976) in the validation cohort. Calibration curves showed good agreement between predicted and observed probabilities. DCA indicated potential net benefit in both cohorts. CONCLUSIONS: To our knowledge, this study developed the first nomogram for retrospectively characterizing delay-risk profiles in children with TT. Internal validation showed good retrospective discrimination within the study cohorts. This nomogram may help identify clinical and care-pathway patterns relevant to quality improvement.