Description

• 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

Epidemiology

Incidence
Predominant age: newborn, more common in premature newborns

Prevalence

• 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

Genetics
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