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- Although the term “testicular torsion” (TT) is most commonly used, it is a pathologic misnomer. “Torsion of the spermatic cord” is the anatomically correct description of the urologic emergency in which the testis twists on its spermatic cord axis, occluding blood flow to the testis.
- TT is classified as extravaginal torsion (predominant in the neonatal period) or intravaginal torsion (most common during the pubertal period).
- Rapid diagnosis and correction is necessary to save testicular tissue. Duration of ischemia and degree of spermatic cord twisting are the primary determinants of testis viability.
- Reported to be as high as 1 per 4,000 and as low as 4.5 per 100,000 males ≤25 years
- Peak incidence is bimodal: the 1st year of life (likely the 1st month) and the pubertal period
- The only known risk factor is the anatomic “bell-clapper” deformity (see “Pathophysiology”).
- There have been reports of increased incidence of extravaginal TT in colder climates. Large database studies have refuted this observation.
- Family history
- There are associated conditions that do not increase risk of TT itself but may alter the entity’s presentation, thus increasing the risk of delayed presentation and initial misdiagnosis.
- Onset of symptoms with physical activity or genital trauma
- Undescended (cryptorchid) testis
- Clear predispositions have not been identified.
- A meta-analysis found up to 10% of unilateral torsion patients have an affected 1st-degree relative. Incidence among family members may be higher in bilateral cases.
- Paramount are awareness of genital pathology unique to pubertal boys and promptly seeking medical attention at onset of symptoms.
- Caretakers of patients with developmental, cognitive, or social disorders should be educated about scrotal pathology unique to the adolescent period (including TT and testis tumors) as these patients are less likely to report symptoms.
- Testicular compartment anatomy
- The spermatic cord suspends the testis in a compartment between parietal and visceral layers of tunica vaginalis (TV; derived from peritoneum).
- The parietal and visceral TV are fused at the posterolateral border (forming a mesentery).
- The gubernaculum fuses the testis to the TV at the inferior pole.
- These points of fusion fix the testis in the scrotum. If either the tunical mesentery or gubernacular fixation is deficient, the testis is free to rotate within the TV compartment (commonly called the “bell-clapper deformity”).
- The incidence of bell-clapper deformity in autopsy series has been reported to be ~12%, much higher than the incidence of TT.
- Blood supply to the testis
- The primary arterial supply is the testicular (gonadal) arteries (branches off the aorta).
- The deferential artery (branch off the inferior vesical artery) and cremasteric artery (branch off the inferior epigastric artery) provide supplemental arterial support.
- The testicular, deferential, and cremasteric arteries have collateral connections at the tail of the epididymis; thus, torsion of the spermatic cord effectively occludes all blood flow to the testis.
- Extravaginal torsion
- Primarily occurs in the neonatal period (only 11% of torsion after 1 month of age has been reported as extravaginal)
- 10% of all TT
- In the neonatal period, the TV may not be fused within the scrotum, allowing the spermatic cord and TV to twist as a unit.
- This mechanism of neonatal torsion is distinct from that of a pubertal/postpubertal male.
- The incidence of contralateral bell-clapper deformity noted during surgical exploration of neonatal torsion has been reported.
- There is controversy on whether or not to surgically explore cases of neonatal torsion without acute changes given the unknown duration of ischemia (e.g., potentially as long as labor), decreased likelihood of contralateral bell-clapper deformity, and risks of general anesthesia in the newborn period.
- Cases of occult contralateral testis ischemia have been reported at time of preventative fixation.
- Extravaginal torsion may occur prior to birth (e.g., a “vanishing testis”). These children may only have a palpable testis remnant.
- Intravaginal torsion
- Commonly the result of bell-clapper anatomy
- The spermatic cord twists medially/inward approximately 2/3 of the time.
- A clear explanation for the increased incidence of TT in the pubertal period is lacking. Most theorize a connection with increased testicular growth and hormonal changes.
- Given the high incidence of a contralateral bell-clapper deformity, preventative fixation of the contralateral side is standard practice.
Commonly Associated Conditions
Intermittent TT (extravaginal)
- Patients will report history of recurrent episodes characteristic of TT (see “History” and “Physical Exam”).