Testicular torsion occurs when the testicle is twisted on the spermatic cord, which holds the testicle in place within the scrotum and is the source of blood to the testicle. This twisting cuts off the blood supply to the testicle. Symptoms include sudden and severe pain in one testicle, and scrotal swelling may soon develop. Please note: Testicular torsion should be treated as a medical emergency. If the flow of blood to the testicle is not restored within 6 hours, the testicle can die.