• Incomplete or improper descent of one or both testicles; also called undescended testes (UDT) (1)
  • Normally descent is in month 7 to 8 of gestation. The cryptorchid testis may be palpable or nonpalpable.
  • Can be congenital or acquired
  • Types of cryptorchidism
    • Prescrotal: at or above scrotal inlet
    • Abdominal: testis located inside the internal inguinal ring
    • Canalicular: testis located between the internal and external inguinal rings
    • Ectopic: located outside the normal path of testicular descent; 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 due to scar tissue after inguinal surgery.
    • Also may be referred to as palpable versus nonpalpable (1)
  • System(s) affected: reproductive
  • Synonym(s): UDT


Predominant age: newborn, more common in premature newborns


  • 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.
  • Descent at 6 to 9 months of age is rare (1).

Etiology and Pathophysiology

  • Not fully understood, 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), and neural factors (ilioinguinal nerve and genitofemoral nerve)
    • Insulin-like growth factor 3 (IGF-3) or androgen receptor gene (1)
    • Environmental factors acting as endocrine disruptors
  • Major regulators of testicular descent are the Leydig cell–derived hormones, testosterone, and IGF-3.
  • Risk of ascent as high as 32% in retractile testis

Increased risk of UDT in first-degree relatives suggests a genetic etiology.

Risk Factors

  • Family history: highest risk if brother had UDT, followed by uncle and then father
  • Low birth weight, prematurity, and small for gestational age (1)
  • Retractile testes are at increased risk for ascent.
  • Maternal smoking and diabetes during gestation

Commonly Associated Conditions

  • Anatomic anomalies: inguinal hernia/hydrocele, abnormalities of vas deferens and epididymis, hypospadias, meningomyelocele
  • Endocrine disorders: intersex abnormalities, hypogonadotropic hypogonadism, germinal cell aplasia
  • Genetic disorders: Prune-belly syndrome, Prader-Willi syndrome, Kallmann syndrome, cystic fibrosis
  • Wilms tumor

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