Diagnosing with a TWIST: Systematic Review and Meta-Analysis of a Testicular Torsion Risk Score

The Testicular Workup for Ischemia and Suspected Torsion (TWIST) score is a 7-point tool to evaluate acute scrotal pain. Parameters include testicular swelling (2 points), hard testis (2), high-riding testis (1), absent cremasteric reflex (1) and nausea/vomiting (1). This review aimed to determine the diagnostic utility of TWIST and its role in risk stratification.

A systematic review and meta-analysis of diagnostic test accuracy was conducted. Five risk stratification systems were explored, including the Barbosa (0-2, 3-4, 5-7) and Sheth (0, 1-5, 6-7) scoring systems, to obtain sensitivity, specificity and area under the receiver operating curve.

Thirteen studies were identified, 9 prospective studies proceeded to meta-analysis of diagnostic test accuracy and 5 pediatric studies (1,060 patients, 199 torsions) were included in the primary analysis. The most accurate risk stratification system was Barbosa (0-2, 3-4, 5-7), with an AUC of 0.924 (95% CI: 0.865, 0.956). Barbosa showed favorable sensitivity in low-risk patients (0.984), facilitating rule out of torsion, and favorable specificity (0.975) in high-risk patients, facilitating urgent surgical exploration. Sensitivity and specificity in intermediate-risk patients were 0.922 and 0.682, respectively, indicating a need for further workup with ultrasound. Using this stratification, 65.2% of patients were low-risk, 19.9% were intermediate-risk and 14.9% were high-risk. Per 100 presentations of acute scrotum, there was a missed torsion rate of 1.6/100, ultrasound rate of 19.9/100 and negative exploration rate of 2.5/100.

TWIST is an effective tool for suspected testicular torsion and is appropriate for widespread adoption. The Barbosa scoring system is reliable and reduces reliance on scrotal ultrasound.