• One or both testes are not present within the dependent portion of the scrotal sac

Risk Factors
  • Strong
    • FHx cryptorchidism
    • Prematurity
    • Low birth weight (<2.5 kg) and/or small for gestational age
  • Weak
    • Environmental exposures
    • Maternal alcohol use
    • Gestational diabetes
    • Prior inguinal surgery
Differential diagnosis
  • The prevalence of cryptorchidism in newborn term infants is 2% to 9% worldwide. [2] 
  • This decreases to 1% to 2% after the first few months of life
    • Congenital cryptorchidism may spontaneously resolve with the neonatal peak of testosterone by 3 months. [3] 
  • There is controversy regarding reports of increasing incidence
    • Potentially due to endocrine disruption/environmental exposures
  • Two thirds of cases are unilateral, while the remainder are bilateral
  • Hormonal
    • Testosterone, mullerian inhibiting substance, insulin-like 3 hormone or its receptor LGR8, epidermal growth factor and/or oestrogens. [8]
  • Environmental or maternal toxins
    • Organochlorines, environmental oestrogens, phthalate esters, smoking and pesticides
    • Maternal alcohol consumption. [3] [7] [9]
  • Genetic
    • Up to 23% of cases have been associated with familial clustering
    • Mutations in insulin-like factor 3 and its receptor, LGR8, have been demonstrated in a small number of cases
  • Mechanical
    • Problems with development of the gubernaculum
    • Patent processus vaginalis
    • Impaired intra-abdominal pressure
  • Neuromuscular
    • Abnormalities of the genitofemoral nerve's calcitonin gene-related peptide or the cremasteric nucleus 
Clinical features
  • Common
    • Presence of risk factors
    • Malpositioned or absent testis
    • Palpable cryptorchid testis
    • Non-palpable testis 
    • Testicular asymmetry
    • Scrotal hypoplasia or asymmetry
    • Retractile testis
  • Uncommon
    • Ascending cryptorchidism
    • Hypospadias
    • Micropenis
    • Secondary sex characteristics/pubertal signs in prepubertal/pubertal patients
    • Surgical scar in the inguinal region
  • Incomplete migration of the testis during embryogenesis
    • This occurs in both androgen-dependent and androgen-independent phases. [14]
  • Less commonly, the underlying aetiology is either absent testis or severely atrophic testis (nubbin)
    • Usually thought to be secondary to malformation or the result of testicular torsion.
  • Ultrasound
    • Testis can be identified, either within the inguinal canal or as it emerges into the superficial inguinal pouch
  • MRI
    • Testis is identified along its normal path of descent
  • Hormonal evaluation
    • With hCG stimulation test no increase in testosterone after hCG, in conjunction with elevated basal rates of gonadotropins LH and FSH, signifies that the testes are absent
  • Retractile testicle(s)
    • Annual follow-up examination
  • Undescended testicle(s): prepubertal
    • No hypospadias: both testicles palpable
      • Orchiopexy
    • No hypospadias: one testicle palpable
      • Examination under anaesthesia + orchiopexy
      • Surgical exploration
    • No hypospadias: no testicle palpable
      • hCG stimulation test
    • Eith hypospadias
      • Endocrinology and/or genetic + urology referral
  • Undescended testicle: postpubertal
    • Orchiopexy ± biopsy
    • ? Orchiectomy
  • Patient outcomes depend on multiple factors
    • Unilateral versus bilateral cryptorchidism
    • Llocation of cryptorchid testis
    • Age at surgical correction
  • Successful surgical correction has been reported as 92% to 95% for testes located beyond the external inguinal ring
    • Failure rates increase for testes in higher locations
  • Rates of testicular cancer may be somewhat higher compared to the general population
  • Rates of malignancy are increased nearly 6 times in patients who undergo late surgical correction or do not undergo correction of cryptorchidism compared to patients who undergo early orchiopexy. [28] [41]
  • Chance of later neoplasia:
    • Unilateral undescended testicle 1 in 120
    • Bilateral undescended testicles 1 in 44
    • The higher the testis is in the abdomen, the higher the risk appears. [28] [41]
  • Increasingly, cryptorchid patients who are infertile are using assisted reproduction and testis sperm retrieval
    • Often sperm can be retrieved in adult men with azoospermia with repaired uni- or bilaterally undescended testes. [42]