The differential diagnosis of the acutely swollen or painful scrotum also includes torsion of the testicular appendage, epididymitis, orchitis, hernia, varicocele, tumor, trauma, idiopathic scrotal edema, fat necrosis, viral inflammation, and Henoch–Schönlein purpura. As testicular torsion is the diagnosis requiring the most urgent action, it should be first on the differential diagnosis list. Testicular torsion may result in irreversible damage to the involved testis. It may also affect the contralateral testicle. Recent studies have examined the possible immunologic mechanism for this global effect on fertility but the exact pathophysiology has not been established.24,25