testes (undescended, incompletely)

Last reviewed 01/2018

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.