Undescended Testicles

After the first year of life, true undescent occurs in about 0.7% of boys.

The testis determining factor once thought to be the HY antigen is now known to be SRY, or the sixth determining region of the Y chromosome.

A recent study suggests that the number of boys with cryptorchidism may be increasing.

Retractile testicles are rare before the age of two weeks.

Spontaneous descent by three months to a year is more likely in babies with low birth weights or pre-term infants. A number of these testicles may secondarily “ascend.”

Siblings of boys with undescended testes are at increased risk for cryptorchidism, with a reported incidence of up to 10%.

To distinguish retractile testicles from ones truly undescended is important, as goals of treatment of undescended testicles include:

possible enhancement of fertility treatment of associated hernias reduction of effects of external injury by scrotal placement improvement of aesthetics and possible prevention of malignant degeneration.

The possibility of malignant degeneration in a patient with an undescended testicle does not reside solely with the testicle that is/was undescended. Malignant degeneration may occur in the contralateral so-called “normal” testicle.

Radiologic evaluation, such as ultrasounds, CT scans and MRI scans, is generally not helpful. Timing of orchiopexy is recommended for sometime before the age of two years because histologic changes in the undescended testicle begin at about two years of age with increasing fibrosis of interstitial tissue. THIS PROCESS IS NOT REVERSIBLE. An increased incidence of epididymal abnormalities in undescended testes contributes to infertility.


A patent processus vaginalis and abnormal epididymis are commonly associated with undescended testicles. Moreover, when the processus vaginalis is patent, the ipsilateral epididymis is more likely to be abnormal. It is postulated that the patency of the processus vaginalis and epididymal maldevelopment are related to androgen deficiency.

Epididymal anomalies associated with cryptorchidism include agenesis, detachment of the caput or cauda epididymis, atresia, elongation with looping epididymis or vas, and widening of the mesentery between the testis and epididymis.

Anorchia may occur in 3-5% of boys operated on for cryptorchidism. Anorchia is unilateral in about 85% of these cases. The HCG stimulation test to document a testosterone surge has been shown not to be a reliable indicator of bilateral testicular agenesis. Extra and intraperitoneal exploration (when indicated) is still recommended for nonpalpable testes.


A significant decrease in the number of spermatogonia per tubule (S:T ratio) in undescended testes and a less prominent reduction on contralateral descended testes as early as the second year of life has been noted. Cryptorchid testes also have atrophic Leydig cells, supporting the observation that testosterone secretion is impaired in cryptorchidism during early infancy.

Patients with poor testicular histology (S:T ratio less or equal to 0.1) and at high risk for impairment of fertility may benefit from treatment with Buserelin, a luteinizing, hormone-releasing hormone (LHRH) analogue. A significant increase in mean S:T ratio was found in testes rebiopsied after orchiopexy and six months after Buserelin treatment, while no change was seen after orchiopexy alone.

Although the retractile testicle is considered a normal variant, some studies suggest that not all testes diagnosed as retractile have a benign course. Some apparently ascend into the undescended position while others show volume loss and histological abnormalities that are similar but less severe than those found in cryptorchid testes. Additionally, there are reports of infertile adults with persistent retractile testicles who have improved sperm counts after scrotal orchiopexy.

In some instances, testes confirmed to be intrascrotal under anesthesia later required orchiopexy. Ascended testes may be previously retractile, or a history of temporary spontaneous descent during the first year of life may be present.

The etiology of testicular ascent is postulated to be the relative shortening of the spermatic cord with gross “resorption” of a patent processus vaginalis or development of adhesions around a retractile testicle. This phenomenon underscores the need for periodic testicular examination in all boys.

HCG treatment is sometimes suggested, as it is non-surgical. However, this technique requires multiple injections and only in about 10% of cases is there permanent testicular descent. In a large percentage of cases there is ascent once more of the testicle after HCG withdrawal. Furthermore, there is no treatment of the underlying hernia.

However, in cases where both testicles are non-palpable, a course of HCG may make the testicles easier to palpate by enlarging them and the spermatic vessels.

LHRH, a synthetic analogue of pituitary gonadotropin-releasing hormone, appears to have 2-3 times the success of HCG; however, this result is still substantially less than the result of surgery.


At present, surgical treatment is advocated, in most cases, at approximately one year of age. This recommendation is based on two observations: spontaneous postnatal testicular descent is unlikely after this age, and histological abnormalities are subsequently more likely. Scrotal positioning also allows early detection of any testicular cancer, reduced risk of trauma and torsion, and improvement in germ cell function and ultimate prognosis of fertility.

The majority of parents opt for surgical treatment of undescended testicles because of the reasons outlined, such as the associated hernia, and also because they are unwilling to put their children through injections and the possible side effects of these hormones. Furthermore, because of the low benefit rate of hormonal treatment and the high success rate of single stage surgery, most children can undergo scrotal placement of testes by about 12 months of age.

Surgery is done under an outpatient general anesthetic. The inguinal canal is opened and the testicle identified and dissected free. A passageway is made into the scrotum on the side of the affected testis, and a small scrotal incision is made. A small scrotal pouch is formed and the testicle placed within it and secured. The wounds are then closed with absorbable sutures.

Complications of surgery are unusual but may include testicular atrophy, retraction and hernia formation. Placement of an artificial testis in those in whom a testis is absent may be an option for some teenage boys, who may be self-conscious. (See Saline-Filled Testicular Implants.)


Semen quality may be impaired in men with a history of unilateral cryptorchidism, but reduction in paternity rates in these men has not been conclusively shown.

For men with a history of bilateral cryptorchidism, the prognosis for fertility is clearly worse and not proven to be improved by type or timing of treatment.

The risk of testicular cancer in men with a history of cryptorchidism has been adjusted downward in recent years. There now exists a relative risk of 4.7% in men with a history of cryptorchidism. This is essentially for intra-abdominal testicles, and this risk is not altered by orchiopexy. Approximately 15-20% of tumors occur in the contralateral descended testis.

Most tumors occurring in testes after previous successful orchiopexy are commonly non-seminomatous germ cell tumors, while those arising in abdominal testes are most frequently seminomas.

Recent studies have recommended non-intervention in patients older than 32 years with persistent cryptorchidism after weighing the risk of malignancy versus the risk of anesthesia.