A 17-year-old man is evaluated for possible epididymitis. He reports exquisite, unilateral, left-sided scrotal and testicular pain and tenderness. The pain started suddenly about 3 hours earlier, and he denies any recent history of trauma, fever, chills, dysuria, or urethral discharge. His most recent sexual activity involved condomless vaginal intercourse approximately 10 days prior. His physical examination reveals a swollen, tender, and high-riding testicle and loss of the cremasteric reflex. In addition, palpating along the posterior region of his left spermatic cord elicits pain. A point-of-care urinalysis is performed and is negative for cells and markers of inflammation.