undescended testes (incompletely descended)

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The undescended testis lies along the correct path of descent but outside the scrotum. It may be abdominal, inguinal or retractile.

The incidence of testicular undescent is:

  • 20% in premature boys (100% in male neonates of 32 weeks gestation)
  • 2% in boys born at full term boys
  • 1% at l year

There is little evidence that testes descend spontaneously after the first year.

The right testis is affected alone in 50% of cases and the left alone in 30%. The condition is bilateral in 20%.

The scrotum is often underdeveloped and flattened. At operation, the testis often appears grossly abnormal. It is small and soft, and has a dissociated epididymis. It is accompanied by a hernial sac.

Absence of testicular tissue suggests intrauterine torsion or true testicular agenesis. If the latter is suspected, than an abdominal ultrasound should be performed to check for renal agenesis.

Last reviewed 01/2018

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