Pilot feasibility study of transscrotal near infrared spectroscopy in the evaluation of adult acute scrotum

Purpose: We investigated the usefulness of transscrotal near infrared spectroscopy that measures testicular oxygen saturation (StO₂%) in the diagnosis of testicular torsion vs other causes of the acute scrotum in adults. Materials and Methods: Between January and May 2009, 16 adult males presenting with acute scrotum underwent StO₂% measurement of the affected and unaffected testis using near infrared spectroscopy followed by color Doppler ultrasound. If surgically explored, near infrared spectroscopy was performed at surgery and on postoperative day 1. Data were presented as means ± SD and/or normalized to the internal control. Cutoff value was generated for the StO₂% difference between the affected testis and control side. Results: Sixteen males with acute scrotum of mean duration 12 hours were enrolled. Of 11 patients with abnormal Doppler undergoing surgical exploration, mean StO₂% of the affected testis at presentation and at surgery decreased from 40.09 ± 2.66 (range 36 to 44) to 37.18 ± 3.31 (range 32 to 42), respectively, while StO₂% of the unaffected testis remained 63.09 (range 55 to 69) both at presentation (SD 4.72) and at surgery (SD 4.98). Of the 11 surgically explored, 4 had orchiectomy and 7 patients underwent surgical detorsion. At presentation and at surgical exploration of the detorsed group, the mean normalized difference between the StO₂% values of the affected and unaffected sides was -16.12 and -25.9, respectively. A cutoff value of -11.5 was measured for the StO ₂% difference between the affected testis and control side at presentation in patients who underwent surgery. Conclusions: Near infrared spectroscopy identified all surgically confirmed cases of testicular torsion when affected testis StO₂% was more than 11.5 units lower than the contralateral testis. In pilot testing, near infrared spectroscopy is a rapid, noninvasive, easy and safe method for the differential diagnosis of adult human testicular torsion.