Description

• Incomplete or improper descent of one or both testicles; also called undescended testes (1)
• Normally, descent is in the 7th to 8th month of gestation. The cryptorchid testis may be palpable or nonpalpable.
• Types of cryptorchidism
  • Abdominal: located inside the internal ring
  • Canalicular: located between the internal and external rings
  • Ectopic: located outside the normal path of testicular descent from abdominal cavity to scrotum; may be ectopic to perineum, femoral canal, superficial inguinal pouch (most common), suprapubic area, or opposite hemiscrotum
  • Retractile: fully descended testis that moves freely between the scrotum and the groin
  • Iatrogenic: Previously descended testis becomes undescended secondary to scar tissue after inguinal surgery, such as an inguinal hernia repair or hydrocelectomy.
  • Also may be referred to as palpable versus nonpalpable (1)
• System(s) affected: reproductive
• Synonym(s): undescended testes (UDT)

Epidemiology

• Predominant age: premature newborns
• Predominant sex: male only

• In the United States, cryptorchidism occurs in 1–3% of full-term and 15–30% of premature newborn males (2).
• Spontaneous testicular descent occurs by age 1 to 3 months in 50–70% of full-term males with cryptorchidism.
• Descent at 6 to 9 months of age is rare (1).

Etiology and Pathophysiology

• Not fully known
• May involve alterations in
  • Mechanical factors (gubernaculum, length of vas deferens and testicular vessels, groin anatomy, epididymis, cremasteric muscles, and abdominal pressure), hormonal factors (gonadotropin, testosterone, dihydrotestosterone, and müllerian-inhibiting substance [MIS]), and neural factors (ilioinguinal nerve and genitofemoral nerve)
  • Major regulators of testicular descent from intra-abdominal location into the bottom of the scrotum are the Leydig cell–derived hormones, testosterone, and insulin-like growth factor 3 (IGF-3).
  • Mutations in the gene for IGF-3 and in the androgen receptor gene have been evaluated as possible causes of cryptorchidism as well as chromosomal alterations (1).
  • Environmental factors acting as endocrine disruptors of testicular descent also may contribute to the etiology of cryptorchidism.
• Risk of ascent may be as high as 32% in retractile testis.

Genetics
Occurrence of UDT in siblings as well as fathers suggests a genetic etiology.

Risk Factors

• Family history of cryptorchidism: highest risk if brother had UDT, followed by uncle and then father
• Low birth weight, prematurity, and small for gestational age are associated with a substantial increase in incidence of cryptorchidism (1). Retractile testes are at increased risk for ascent.

Commonly Associated Conditions

• Inguinal hernia/hydrocele
• Abnormalities of vas deferens and epididymis
• Intersex abnormalities
• Hypogonadotropic hypogonadism
• Germinal cell aplasia
• Prune-belly syndrome
• Meningomyelocele
• Hypospadias
• Wilms tumor
• Prader-Willi syndrome
• Kallmann syndrome
• Cystic fibrosis