Pyramidal Thickness: A New Player in Predicting the Need for Pyeloplasty-A Nonrandomized Prospective Study

To evaluate the predictive value of pyramidal thickness and the ipsilateral-to-contralateral pyramidal thickness ratio for pyeloplasty in children with suspected ureteropelvic junction obstruction, and to develop a prediction model incorporating pyramidal thickness-based parameters.

This prospective observational cohort study included 76 children with suspected UPJO between September 2024 and September 2025. Thirty-six patients underwent pyeloplasty and 40 were managed conservatively. The decision to perform pyeloplasty was based on established clinical indications in accordance with current literature. Baseline demographic, ultrasonographic, and diuretic renography findings were recorded. Ultrasonographic parameters included anteroposterior pelvic diameter (APD), parenchymal thickness, pyramidal thickness, and the ipsilateral-to-contralateral pyramidal thickness ratio. ROC analyses and multivariable logistic regression were performed to identify predictors of pyeloplasty and develop a prediction model.

At baseline, patients who underwent pyeloplasty had significantly lower pyramidal thickness (2.1 vs 3.15 mm, P < .001), lower pyramidal thickness ratio (0.48 vs 0.61, P < .001), and larger APD (21 vs 15.5 mm, P < .001) than conservatively managed patients. Pyramidal thickness and pyramidal thickness ratio demonstrated good discriminatory performance for pyeloplasty (AUC 0.800 and 0.816, respectively). Multivariable analysis identified lower pyramidal thickness (OR 0.005, P < .001), lower parenchymal thickness (OR 0.18, P = .034), and larger APD (OR 1.41, P = .018) as independent predictors. The resulting prediction model achieved excellent discrimination (AUC 0.915). Following pyeloplasty, all ultrasonographic parameters showed significant longitudinal improvement (all P < .001).

Pyramidal thickness and the pyramidal thickness ratio are reproducible sonographic parameters that may serve as useful adjuncts in identifying children with suspected UPJO who are more likely to undergo pyeloplasty.