Evaluating the TWIST score and point-of-care ultrasound for paediatric testicular torsion

Abstract

Background: An acute scrotum is an urological emergency. One of its most important causes is testicular torsion, which can result in testicular necrosis unless quickly diagnosed and treated. Along with point-of-care ultrasound (POCUS), the Testicular Workup for Ischemia and Suspected Torsion (TWIST) score can be used to differentiate between testicular torsion and other causes of an acute scrotum. However, their diagnostic performance when undertaken by emergency physicians (EPs) and paediatricians in the emergency department (ED), as opposed to urologists/radiologists, is uncertain.

Methods: This retrospective observational study investigated patients aged ≤15 years with an acute scrotum who visited a paediatric tertiary care hospital's ED between March 2018 and August 2022. The diagnostic accuracy of the TWIST score and POCUS when performed by EPs and paediatricians to diagnose testicular torsion was calculated. Each TWIST score served as a cut-off. For practical purposes, a cutoff ≥3 points was used for sensitivity and the negative predictive value (NPV), and a cutoff ≥5 points was used for specificity and the positive predictive value (PPV). The final diagnosis served as the reference standard.

Results: Of 512 patients, 55 (11%) had testicular torsion. The TWIST score had 91% sensitivity (95% CI 80%-97%), 95% specificity (95% CI 93% to 97%), 63% PPV (95% CI 50% to 75%) and 99% NPV (95% CI 97% to 100%). When positivity was defined as either impaired testicular blood flow or the whirlpool sign, the sensitivity, specificity, PPV and NPV were 96% (95% CI 87% to 100%), 95% (95% CI 93% to 97%), 70% (95% CI 58% to 80%) and 100% (95% CI 98% to 100%) respectively.

Conclusion: Although the TWIST score and POCUS had high diagnostic accuracy for paediatric testicular torsion when performed by EPs or paediatricians in the ED, the non-negligible, false-negative rate indicated that the TWIST score should be used for risk stratification rather than as an exclusionary method.

Keywords: Prognosis; emergency department; epidemiology; pediatric emergency medicine; ultrasonography.