The term cryptorchidism is derived from the Greek words “kryptos” meaning “hidden” and “orchis” meaning testes.
Incomplete descent of one (unilateral) or both (bilateral) testicles from the abdominal cavity, through the inguinal canal into the scrotum is a multifactorial etiology abnormality that affects 1-1.8% of male infants. It is the most common genitourinary anomaly in male children. Its incidence can reach 3% in full term neonates, rising to 30% in premature boys. In unique cases, cryptorchidism can develop later in life, often as late as young adulthood.
In fact cryptorchidism has been proposed to be part of a "testicular dysgenesis syndrome" which includes hypospadias, reduced semen quality and testicular cancer. These conditions are thought to have a common origin in prenatal testicular maldevelopment, which affects both Leydig and Sertoli cells and germ cell differentiation. During development, the gonads are at first capable of becoming either ovaries or testes. In humans, starting at about week 4 the gonadal rudiments are present within the intermediate mesoderm adjacent to the developing kidneys. At about week 6, sex cords develop within the forming testes. These are made up of early Sertoli cells that surround and nurture the germ cells that migrate into the gonads shortly before sex determination begins. In males, the sex-specific gene SRY that is found on the Y-chromosome initiates sex determination by downstream regulation of sex-determining factors, which leads to development of the male phenotype, including directing development of the early bipotential gonad down the male path of development. Testes follow the "path of descent" from high in the posterior fetal abdomen to the inguinal ring and beyond to the inguinal canal and into the scrotum. In most cases (97% full-term, 70% preterm), both testes have descended by birth. In most other cases, only one testis fails to descend and that will probably express itself within a year. After six months of life therapeutic intervention is indicated, as a spontaneous descent is then unlikely.

A testis absent from the normal scrotal position can be found:

  • along the "path of descent" from high in the posterior (retroperitoneal) abdomen, just below the kidney, to the inguinal ring
  • in the inguinal canal
  • ectopically, that is, to have "wandered" from that path, usually outside the inguinal canal and sometimes even under the skin of the thigh, the perineum, the opposite scrotum, or the femoral canal
  • undeveloped (hypoplastic) or severely abnormal (dysgenetic)
  • to have vanished (anorchia)

In addition to quite common congenital forms, other – rare forms exist:

  • acquired undescended testis - now a well-recognized disorder. It was suggested that acquired undescended testis is in fact congenital because of a short funiculus at birth, which allows scrotum to stay in a low position during early childhood. As boy grows, testis imght get into undescended position. Usually it descends spontaneously, when testosterone levels rises significantly at puberty.
  • retractile testis- can readily move or be moved between the scrotum and canal
  • gliding testes - which can be manipulated into a satisfactory scrotal position but will retract quickly once released. 

In relation to diagnosis, despite a sensitivity of 70-90% in the diagnosis of inguinal testes, ultrasonography is not useful in intra-abdominal cases. Although presenting a better quality, both computed tomography and nuclear magnetic resonance lack sufficient sensitivity and specificity to be considered as gold standard diagnostic tools. The treatment of the cryptorchid testicle(s) before 2 years of age is justified by the increased risk of infertility and malignancy, as well as an associated inguinal hernia and the risk of trauma to the ectopic testicle against the pubis. Furthermore, the psychological stigma of a missing testis for the patient, as well as the parents’ anxiety is also factors that justify this type of treatment.

Associated diseases

Undescended testes are associated with reduced fertility, high rate of anomalies of the epididymis, increased risk of testicular germ cell tumors, and psychological problems when the boy is grown. Undescended testes are also more susceptible to testicular torsion and infarction, and inguinal hernias. To reduce these risks, undescended testes are usually brought into the scrotum in infancy by a surgical procedure called an orchiopexy.

One of the strongest arguments for early orchiopexy is prevention of testicular cancer. About 1 in 500 men born with one or both testes undescended develop testicular cancer, roughly a 4 to 40 fold increased risk. The peak incidence occurs in the 3rd and 4th decades of life. The risk is higher for intra-abdominal testes and somewhat lower for inguinal testes. The most common type of testicular cancer occurring in undescended testes is seminoma (65%); in contrast, after orchiopexy, seminomas represent only 30% of testis tumors.

It is usually treatable if caught early, so urologists often recommend that boys who had orchiopexy as infants be taught testicular self-examination, to recognize testicular masses and seek early medical care for them. Cancer developing in an intra-abdominal testis would be unlikely to be recognized before considerable growth and spread, and one of the advantages of orchiopexy is that a mass developing in a scrotal testis is far easier to recognize than an intra-abdominal mass.

Cryptorchidism is also associated with some types of hypogonadotropic hypogonadism and gonadal dysgenesis caused by Swyer syndromeKlinefelter syndrome and Kallmann syndrome.


Risk factors

Risk factors include premature birth, genetic predisposition, small-for-gestational-weight (SGA), birth weight < 2500 g as well as environmental factors (nicotine, alcohol, pesticides) and endocrine disorders (e.g. disrupted hypothalamic-pituitary-gonad axis). 10 % of the cases are bilateral and are commonly associated with complex syndromes or other congenital malformations such as abdominal wall defects or neural tube defects.

Many men who were born with undescended testes have reduced fertility, even after orchiopexy in infancy. The fertility reduction after orchiopexy for bilateral cryptorchidism is more marked, about 38%, or 6 times that of the general population.

At least one contributing mechanism for reduced spermatogenesis in cryptorchid testes is temperature. The temperature of testes in the scrotum is at least a couple of degrees cooler than in the abdomen and the temperature rising may damage fertility. Some circumstantial evidence suggests tight underwear and other practices that rise testicular temperature for prolonged periods can be associated with lower sperm counts. Nevertheless, research in recent decades suggests that the issue of fertility is more complex than a simple matter of temperature. It seems likely that subtle or transient hormone deficiencies or other factors that lead to lack of descent also impair the development of spermatogenic tissue.

There is no way to prevent this condition because the exact cause is not known.

Usually, there are no symptoms other than the absence of the testicle in the scrotum (an empty scrotum.) In the minority of cases with bilaterally non-palpable testes, further testing to locate the testes, assess their function, and exclude additional problems is often useful. Pelvic ultrasound or magnetic resonance imaging performed and interpreted by a radiologist can often, but not invariably, locate the testes while confirming absence of a uterus. A karyotype can confirm or exclude forms of dysgenetic primary hypogonadism, such as Klinefelter syndrome or mixed gonadal dysgenesis. Hormone levels (especially gonadotropins and AMH) can help confirm that there are hormonally functional testes worth attempting to rescue, as can stimulation with a few injections of human chorionic gonadotropin to elicit a rise of the testosterone level. Occasionally these tests reveal an unsuspected and more complicated intersex condition.




European Society of Paediatric Urologists' (ESPU) is in favour of using gonadotrophin releasing hormone (GnRH) analogues to improve fertility in boys with undescended testis, particularly in those with bilateral disorders. Although the number of studies is limited and patient numbers are relatively low, GnRH analogues (in some studies used in combination with hCG) do appear to have a statistically significant beneficial effect on fertility indices both when used before orchidopexy and after. A series of human chorionic gonadotropin (hCG) injections (10 injections over 5 weeks is common) is given and the status of the testis/testes is reassessed at the end. Hormone treatment does have the occasional incidental benefits of allowing confirmation of Leydig cell responsiveness (proven by a rise of the testosterone by the end of the injections) or inducing additional growth of a small penis (via the testosterone rise, if the defect in the hypothalamic-pituitary-gonadal axis was present).

In the absence of testosterone generated by Leydig cells or in the case of non functional or absent androgen receptors, testicular descent is arrested at inguino-scrotal stage. In boys, testosterone replacement is initiated most frequently with testosterone enanthate 50 mg per month intramuscularly, with increasing dose every 6 months until 250 mg is given every 3 weeks in the third year. While testosterone treatment effectively induces virilisation including penile growth, pubic and male hair and beard growth, change of voice, libido, and pubertal growth spurt, testicular volume remains small, lacking spermatogenesis. LH stimulates intratesticular testosterone secretion by Leydig cells inhibiting Anti-Müller’s hormone production of the Sertoli cells, FSH induces testis growth via proliferation of seminiferous tubules, and both stimulate Inhibin B secretion by the Sertoli cells and sperm maturation.

Surgical therapy

Orchiopexy (or orchidopexy) is a surgery to move an undescended (cryptorchid) testicle into the scrotum and permanently fix it there. Orchiopexy typically also describes the surgery used to resolve testicular torsion. The undescended testicle may be located within the normal line of descent (for example, in the inguinal canal) or high in the scrotum or ectopically (i.e. the abdomen). During laparoscopy the surgeon uses an endoscope through the umbilicus to locate the testicle, and through other small opening(s) performs the procedure to complete the orchiopexy. The higher the testicle, the less successful the procedure. However, the procedure has a high success rate overall. In the open orchiopexy, if the testis isn’t found in the inguinal canal, a retroperitoneal and intraperitoneal exploration is carried out through the deep ring. In both approaches, the viable testis is brought down into the scrotum by mobilization of the spermatic pedicle; spermatic vessel ligation isn’t employed in any patient in this series. The finding of blind-ending vas and vessels indicated vanishing testis and further exploration is abandoned after removal of the nubbin of tissue at the termination of the vas and vessels. The considered atrophic testes are removed.

The incidence of azoospermia in unilateral cryptorchidism is 13% and this figure increases to 89% in untreated bilateral cryptorchidism, making cryptorchidism the most common etiologic factor of azoospermia in the adult. A major advancement in recent years has been the introduction of IVF with ICSI which allows successful fertilization with the sperm obtained directly from testicular tissue. IVF-ICSI allows for pregnancy in couples where the man has irreversible testicular azoospermia as long as it is possible to recover sperm material from the testes. Pregnancies have been achieved in situations where azoospermia was associated with cryptorchism and sperm where obtained by testicular sperm extraction (TESE).

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