Aims: To develop a decision tree model using US features to differentiate testicular torsion and other conditions of acute scrotum and to investigate predictive parameters of unsalvageable testis in testicular torsion.
Materials and methods: Scrotal US was reviewed in patients aged <30 years who presented with acute scrotum from 2014 to 2020. US findings of whirlpool sign, testicular volume ratio, heterogeneous echotexture, testicular vascularity, epididymis enlargement and/or hyperemia, and avascular nodule were evaluated and compared. A decision tree model was created using the conditional inference tree analysis and the accuracy was calculated. Univariate logistic regression analysis was performed to find out the predictive US features of unsalvageable testes.
Results: Total of 381 patients (13.2±7.2 years old; range, 1 day-30 years) were included. Thirty-four patients were diagnosed with testicular torsion, and the others with orchitis or epididymo-orchitis (n=59), epididymitis (n=264), and appendage torsion (n=24). In the conditional inference tree analysis, whirlpool sign, avascular nodule, and increased testicular vascularity were the most significant discriminators (p<0.001), and the whirlpool sign was the first discriminator. The overall accuracy of the conditional inference tree was 91.1% (95% confidence interval [CI], 87.8-93.7%). Heterogeneous echotexture (odds ratio [OR], 74.99; 95% CI, 2.75-2046.26; p=0.01) and symptom-to-operation time >24 h (OR, 49.28; 95% CI, 1.92-1262.03; p=0.02) were significant predictors of unsalvageable testis.
Conclusions: Conditional inference tree analysis showed that the whirlpool sign of the spermatic cord, avascular nodule, and altered testicular vascularity were significant discriminators. Heterogeneous echotexture and symptom-to-operation delay were important prognostic factors for unsalvageable testis.