Early Postoperative Testicular Volume Ratio Is Associated With Long-Term Growth Failure After Unilateral Redo Orchiopexy in Children.

Abstract

Background: Redo orchiopexy is usually evaluated based on the position of the scrotum after surgery, but satisfactory scrotal placement may not necessarily reflect preserved long-term testicular growth. In this study, we evaluated whether the early postoperative testicular volume ratio (TVR) is associated with long-term growth failure after unilateral redo orchiopexy in children.

Methods: This retrospective single-center cohort study included children who underwent unilateral redo orchiopexy between January 2013 and January 2023. Early postoperative ultrasonography was performed 6-12 months after surgery, and subsequent follow-up ultrasonography was performed at ≥24 months. TVR was calculated as the operated testicular volume divided by the contralateral testicular volume × 100. Long-term growth failure was defined as long-term TVR <50% and/or the absence of an interval increase in operated testicular volume beyond expected ultrasonographic measurement variability. The discriminative ability of early TVR was assessed using receiver operating characteristic (ROC) analysis. The ROC-derived cutoff was considered exploratory because it was derived and evaluated in the same cohort.

Results: Sixty-eight children met the inclusion criteria. The mean age at redo orchiopexy was 7.8 ± 2.9 years, and the median follow-up was 36 months. Long-term growth failure occurred in 20 patients (29.4%). Children with growth failure had significantly lower early TVR than those with preserved growth (48.6 ± 13.2% vs. 80.4 ± 16.8%, p < 0.001). Early TVR showed good apparent discrimination, with an area under the curve (AUC) of 0.84 (95% confidence interval [CI], 0.72-0.96). In the exploratory multivariable model, each 10-percentage-point increase in early TVR was associated with a lower odds of growth failure (odds ratio [OR] 0.56; 95% bootstrap CI 0.36-0.84). The apparent model AUC was 0.86, and the optimism-corrected AUC after 1000 bootstrap resamples was 0.81. The exploratory 55% cutoff yielded 82% sensitivity, 78% specificity, 69% positive predictive value, and 88% negative predictive value.

Conclusions: Early postoperative TVR is associated with long-term testicular growth failure after unilateral redo orchiopexy. A TVR of approximately 55% may help identify children who require closer ultrasonographic surveillance, but this threshold is hypothesis-generating and requires external validation before clinical implementation. TVR should be interpreted as an imaging-based risk stratification marker rather than a direct measure of endocrine, fertility, or histologic testicular function.