The etiology of cryptorchidism is multifactorial. Extensive research and clinical observations have elucidated some of the factors involved, but the exact mechanism of cryptorchidism has proved elusive.

Birth weight is the principal determining factor for undescended testes at birth to age 1 year, independent of the length of gestation.

One study found that almost 23% of index patients with undescended testes had a positive family history of cryptorchidism, as opposed to 7.5% in control families. [3] The familial cluster is 3.6 fold overall, 6.9 if a brother is affected and 4.6 if the father. Mutations in the homeobox gene HOXA10, which plays a pivotal role in regulation of testicular descent, may be involved in select cases. [45]

Transabdominal descent of the testis involves differential growth of vertebrae and pelvis until 23 weeks’ gestation. Afterward, further descent is facilitated by the development of the gubernaculum, processus vaginalis, spermatic vessels, and scrotum. [2] A normal hypothalamic-pituitary-gonadal axis is a prerequisite for testicular descent. [6] Furthermore, testosterone and its conversion to dihydrotestosterone (DHT) are also necessary for continued migration, especially during the inguinoscrotal phase. [789]

Exposure to endocrine-disrupting chemicals may contribute to cryptorchidism, and may account for the increasing incidence rate of cryptorchidism seen in some regions. Synthetic chemicals identified as endocrine disruptors include phthalates, pesticides, brominated flame retardants, diethylstilbestrol, and dioxins. [10] Different studies have found conflicting data regarding the involvement of müllerian-inhibiting substance, prenatal estrogen exposure, and descendin (a specific gubernacular growth factor) in the pathophysiology of cryptorchidism. [111213]

Although its exact mechanism of action is unclear, the gubernaculum has significant importance in undescended testes. In patients with cryptorchidism, the gubernaculum is not firmly attached to the scrotum, and the testis is not pulled into the scrotum. [14] Both hormonal and mechanical factors appear to mediate the aid of the gubernaculum and descent of the testis. [15] The genitofemoral nerve may also aid in descent and gubernacular differentiation, which may be mediated by calcitonin gene-related peptide. [1617]

Intra-abdominal pressure also appears to play a role in testicular descent. Conditions associated with decreased pressure include prune belly syndromecloacal exstrophyomphalocele, and gastroschisis, among other various syndromes. Each is associated with an increased risk of undescended testes. [1819] The effect of decreased intra-abdominal pressure is most significant during transinguinal migration to the scrotum, probably in conjunction with androgens and a patent processus vaginalis. [2021]

Epididymal abnormalities often accompany undescended testes, but the causal relationship has not been established. In 1992, Elder concluded that most epididymal abnormalities probably do not contribute to maldescent. [22]

Risk factors

Factors that might increase the risk of an undescended testicle in a newborn include:

  • Low birth weight
  • Premature birth
  • Family history of undescended testicles or other problems of genital development
  • Conditions of the fetus that can restrict growth, such as Down syndrome or an abdominal wall defect
  • Alcohol use by the mother during pregnancy
  • Cigarette smoking by the mother or exposure to secondhand smoke
  • Parents' exposure to some pesticides

 

 

The first surgical orchiopexy was attempted in 1820 by Rosenmerkal. However, it was not until 1877 that Annandale performed the first successful orchiopexy. [2

A cricopharyngeal bar, appearing as a prominent indentation behind the lower third of the cricoid cartilage, is related to Zenker’s diverticulum in that it involves limited distensibility of the cricopharyngeus and can lead to the formation of a Zenker’s diverticulum.

However, a cricopharyngeal bar is a common radiographic finding, and most patients with transient cricopharyngeal bars are asymptomatic, making it important to rule out alternative etiologies of dysphagia before treatment. Furthermore, cricopharyngeal bars may be secondary to other neuromuscular disorders.

 

 

 

Overall, 3% of full-term male newborns have cryptorchidism, decreasing to 1% in male infants aged 6 months to 1 year. The prevalence of cryptorchidism is 30% in premature male neonates. Factors that predispose to cryptorchidism include prematurity, low birth weight, small size for gestational age, twinning, and maternal exposure to estrogen during the first trimester. Seven percent of siblings of boys with undescended testes have cryptorchidism. An undescended testis may descend spontaneously during the first few months of life but is unlikely to do so after 6 months (corrected for gestational age). Cryptorchidism may also be acquired, with an initially descended testis ascending out of the scrotum. [1]

In the United States, the prevalence of cryptorchidism ranges from 3.7% at birth to 1.1% from age 1 year to adulthood. Internationally, prevalence ranges from 4.3-4.9% at birth to 1-1.5% at age 3 months to 0.8-2.5% at age 9 months. Cryptorchidism is identified in 1.5-4% of fathers and 6.2% of brothers of patients with cryptorchidism. Heritability in first-degree male relatives is estimated to be 0.67.

 

 

In order for testicles to develop and function normally, they need to be slightly cooler than normal body temperature. The scrotum provides this cooler environment.

  • Testicular cancer. Testicular cancer usually begins in the cells in the testicle that produce immature sperm. What causes these cells to develop into cancer is unknown. Men who've had an undescended testicle have an increased risk of testicular cancer.

    The risk is greater for undescended testicles located in the abdomen than in the groin, and when both testicles are affected. Surgically correcting an undescended testicle might decrease, but not eliminate, the risk of future testicular cancer.

  • Fertility problems. Low sperm counts, poor sperm quality and decreased fertility are more likely to occur among men who've had an undescended testicle. This can be due to abnormal development of the testicle, and might get worse if the condition goes untreated for an extended period of time.

Other complications related to the abnormal location of the undescended testicle include:

  • Testicular torsion. Testicular torsion is the twisting of the spermatic cord, which contains blood vessels, nerves and the tube that carries semen from the testicle to the penis. This painful condition cuts off blood to the testicle.

    If not treated promptly, this might result in the loss of the testicle. Testicular torsion occurs 10 times more often in undescended testicles than in normal testicles.

  • Trauma. If a testicle is located in the groin, it might be damaged from pressure against the pubic bone.
  • Inguinal hernia. If the opening between the abdomen and the inguinal canal is too loose, a portion of the intestines can push into the groin.

 

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Update April 7, 2021