Diagnosing Testicular Torsion before Urological Consultation and Imaging: Validation of the TWIST Score

Purpose: The TWIST (Testicular Workup for Ischemia and Suspected Torsion) score uses urological history and physical examination to assess risk of testis torsion. Parameters include testis swelling (2 points), hard testis (2), absent cremasteric reflex (1), nausea/vomiting (1) and high riding testis (1). While TWIST has been validated when scored by urologists, its diagnostic accuracy among nonurological providers is unknown. We assessed the usefulness of the TWIST score when determined by nonurological nonphysician providers, mirroring emergency room evaluation of acute scrotal pain. Materials and Methods: Children with unilateral acute scrotum were prospectively enrolled in a National Institutes of Health clinical trial. After undergoing basic history and physical examination training, emergency medical technicians calculated TWIST score and determined Tanner stage per pictorial diagram. Clinical torsion was confirmed by surgical exploration. All data were captured into REDCap (TM) and ROC curves were used to evaluate the diagnostic usefulness of TWIST. Results: Of 128 patients (mean age 11.3 years) 44 (13.0 years) had torsion. TWIST score cutoff values of 0 and 6 derived from ROC analysis identified 31 high, 57 intermediate and 40 low risk cases (positive predictive value 93.5%, negative predictive value 100%). Conclusions: TWIST score assessed by nonurologists, such as emergency medical technicians, is accurate. Low risk patients do not require ultrasound to rule out torsion. High risk patients can proceed directly to surgery, with more than 50% avoiding ultrasound. In the future emergency medical technicians and/or emergency room triage personnel may be able to calculate TWIST score to guide radiological evaluation and immediate surgical intervention at initial assessment long before urological consultation.