Testicular Workup for Ischemia and Suspected Torsion (TWIST) score

The Testicular Workup for Ischemia and Suspected Torsion (TWIST) score is a clinical decision tool derived to help emergency providers assess pediatric males presenting with an acute scrotum. Specifically, the most critical and time-sensitive diagnosis of testicular torsion is the focus of this tool, and patients are stratified into low, intermediate, and high risk for this concern.

The derivation study (Barbosa et al. 2013) was a prospective evaluation of 338 pediatric patients with an acute scrotum, assessing a primary outcome of rates of testicular torsion. Notably in this study, the physical assessment was performed by a urologist and all patients had a scrotal ultrasound performed. The NPV for torsion was 100% for scores 0-2 and the PPV was 100% for scores 5-7, making the test performance extremely useful in reducing rates of imaging while improving diagnostic certainty.

A subsequent prospective validation study (Frohlich et al. 2017) enrolled 258 pediatric patients presenting to a tertiary care pediatric emergency department with acute scrotal pain. The primary outcome was rates of surgically confirmed testicular torsion (including diagnoses of intermittent torsion). All patients enrolled received scrotal ultrasounds. This validation demonstrated reduced utility for the TWIST score. Specifically, while higher scores were associated with increased rates of torsion, only a score of 7 had a PPV of 100% for torsion while all lower scores needed an ultrasound to complement the work up.

In conclusion, while this tool utilizes the strata from the derivation study, results should be taken with caution. Higher scores are associated with increased probability of torsion, but further studies are necessary to improve the rule out and rule in power of this tool.

Variable & Associated Points

• Testicular swelling (Yes +2, No 0)
• Hard testes (Yes +2, No 0)
• Absent cremasteric reflex (Yes +1, No 0)
• Nausea or vomiting (Yes +1, No 0)
• High-riding testicle (Yes +1, No 0)

Results:

• Scores of 0, 1, or 2 = Low Risk
• Scores of 3 or 4 = Intermediate Risk
• Scores of 5 or 6 or 7 = High Risk