The spectrum of conditions that affect the scrotum and its contents ranges from incidental findings to pathologic events that require expeditious diagnosis and treatment (eg, testicular torsion, testicular cancer). The most common causes of acute scrotal pain in children and adolescents include testicular torsion, torsion of the appendix testis, and epididymitis. In one review of 238 consecutive boys, ages 0 to 19 years, who presented with acute scrotal pain to a children's hospital over a two-year period, 16 percent had testicular torsion, 46 percent had torsion of the appendix testis, and 35 percent had epididymitis .
The causes of scrotal pain will be reviewed here. The evaluation of scrotal pain or swelling and causes of scrotal swelling are discussed separately. (See "Evaluation of scrotal pain or swelling in children and adolescents" and "Causes of painless scrotal swelling in children and adolescents".)
Testicular torsion is the most dramatic and potentially serious of the acute processes affecting the scrotal contents because it may result in the loss of the testicle. Normal testicular anatomy is depicted in the figure (figure 1).
Intravaginal torsion results from inadequate fixation of the testis to the tunica vaginalis through the gubernaculum testis. The most common abnormality associated with testicular torsion is known as the "bell clapper" deformity: the testicle lacks the normal attachment to the tunica vaginalis (permitting increased mobility) and rests transverse within the scrotum (figure 2) . The bell clapper deformity may be bilateral and predisposes to testicular torsion.
If fixation of the lower pole of the testis to the tunica vaginalis is insufficiently broad-based or absent, the testis may torse (twist) on the spermatic cord (figure 3). The twisting of the spermatic cord within the tunica vaginalis causes venous compression and subsequent edema of the testicle and cord with ultimate ischemia of the testicle caused by arterial occlusion [2,3].