Pathophysiology
Testicular torsion occurs when there is mechanical twisting of the spermatic cord, which suspends the testicle within the scrotum and contains the testicular artery and vein. Twisting of the cord reduces or eliminates blood flow to the testicle. The degree of arterial and venous obstruction depends on the duration and severity of the torsion event. Typically, venous blood flow is compromised first. The increase in venous pressure subsequently causes decreased arterial blood flow, leading to decreased oxygen supply to the testicle, and if untreated, testicular infarction.It is also believed that torsion occurring during fetal development can lead to so-called neonatal torsion or vanishing testis, and is one of the causes of an infant being born with monorchism (one testicle). Intermittent testicular torsion
Intermittent testicular torsion (ITT) is a less serious but chronic variant of torsion. It is characterized by intermittent scrotal or testicular pain, followed by eventual spontaneous detorsion and resolution of pain. Nausea and vomiting may also occur. : 150  Though less pressing, such individuals are at significant risk of complete torsion and possible subsequent orchiectomy and the recommended treatment is elective bilateral orchiopexy. Ninety-seven percent of patients who undergo such surgery experience complete relief from their symptoms. : 316

Extravaginal testicular torsion
Torsion occurring outside of the tunica vaginalis, when the testis and gubernaculum can rotate freely, is termed an extravaginal testicular torsion. This type occurs exclusively in newborns, however, newborns can be affected by other testicular torsion variants as well.
Of children with testicular pain of rapid onset, testicular torsion is the cause of about 10% of cases. Complications may include an inability to have children. The condition was first described in 1840 by Louis Delasiauve. Signs and symptoms
Testicular torsion usually presents with severe testicular pain or pain in the groin and lower abdomen. Pain generally begins suddenly and typically involves only one side. There is often associated nausea and vomiting. The testicle may lie higher in the scrotum due to twisting and subsequent shortening of the spermatic cord or may be positioned in a horizontal orientation. Mild warmth and redness of the overlying area may be present. Elevation of the testicle may worsen the pain. Urinary symptoms, such as pain or increased frequency of urination are also typically absent. Symptom onset often follows physical activity or trauma to the testes or scrotum. Children with testicular torsion may awaken with testicular or abdominal pain in the middle of the night or in the morning. There may be a history of previous, similar episodes of scrotal pain due to prior transient testicular torsion with spontaneous resolution. Complications
Testicular infarction: Testicular damage occurs as a consequence of decreased blood flow, and therefore decreased oxygen and nutrient supply, to the testicle. If the testicle is not viable during surgical exploration, it must be removed to prevent further necrosis, or tissue death. Infertility: The impact of testicular torsion on long-term fertility is not yet fully understood.