Puberty is the most common age at which testicular torsion occurs, with the newborn period being the second most common. The incidence is 1 in 4000 males younger than 25 years
Testicular torsion can be classified into two types, relative to the tunica vaginalis' relationship to the area of the spermatic cord that twists: extravaginal and intravaginal. Extravaginal torsions occur perinatally, during testicular descent and prior to testicular fixation in the scrotum (2). This incomplete fixation of the gubernaculum (the fibrous cord extending from the fetal testis to the fetal scrotum which occupies the potential inguinal canal and guides the testis in its descent) to the scrotal wall allows the entire testes and tunica free rotation within the scrotum (3). The rotation of the cord is "extravaginal" because the rotation of the cord is proximal to the attachment of the tunica vaginalis that encloses the testes. These comprise 5% of all testicular torsions.