Undescended Testis
Undescended testis, or failure of the testis to drop into the scrotum, is one of the most common surgical disorders in childhood. This is also called cryptorchidism. A cryptorchid testis is found in 1 of 125 boys by age 1 year. Cryptochidism occurs more frequently in preterm boys (30%) and almost is associated with an indirect inguinal hernia, although most are not symptomatic. This problem occurs in approximately 0.8% to 1.3% of boys. Surgery is the cornerstone of therapy for the correction of true undescended testis.
Embryology
The testes originate in abdomen and move out through a natural hole in the abdominal wall during the seventh and eighth months of gestation. This hole is called the inguinal canal. The testicle descends through the inguinal canal and into the scrotum during the eighth and ninth months of gestation. This normal movement of the testicle is caused by hormonal influences and another anatomic structure called the gubernaculum. The gubernaculum can be imagined as a cord that pulls the testicle into the scrotum. Although the testicle normally drops into the scrotum it may on occasion move into an abnormal location in the groin or upper leg. The processus vaginalis mentioned in the section on hernias, is drawn into the scrotum with the testicle as well.
Hormonal Influences
Testicular descent into the scrotum is influenced greatly by maternal hormones that stimulate production of other hormones by the fetal testis. Failure of the testicle to descend through the inguinal canal during the third trimester may be related to not enough of a specific type of maternal hormone, failure of the testis to respond to the hormones, inadequate pull from the gubernaculum, or various other factors. More than 80% of undescended testes are only on one side. The other side is usually normal.
Empty Scrotum
An empty scrotum is found in 20% to 30% of premature infants and 1.2% to 4% of mature newborns. This means that there is no testicular tissue that can be found in the scrotum. The diagnosis of true undescended testis may be difficult to determine before age 6 months, particularly in premature infants. Thereafter gentle manipulation by a physician should be able to place the testicle into the low scrotum without much difficulty. There are also other reasons why a scrotum may appear to be empty. The empty scrotum may be caused by a retractile testis which is a normal variant (see below) or by true testicular pathology such as ectopic testes (where the testicle has moved into the wrong position, 3%), dysgenetic or atrophic testes, (abnormal or shrunken testes, 5%), absent testes (3%), or true undescended testes (89%).
Retractile Testes
An empty scrotum in a young child may be the result of a retractile testis caused by an overactive cremaster muscle and inadequate attachment of the gubernaculum to the scrotum. These testes descend into the scrotum spontaneously when children are asleep or relaxed and can be manipulated into the low scrotum on examination. Retractile testes are usually on both sides. The testes remain in the scrotum after early adolescence when the testicle becomes heavier and larger and the cremaster muscle becomes less active. Testicular volume and function of retractile testicles are believed to be normal in adulthood. No surgical treatment is indicated. The use of hormones to treat this condition is controversial and generally not needed.
Ectopic Testes
The ectopic testis is drawn into the thigh, groin, or superpubic area by an abnormally positioned gubernaculum and places the gonad at risk for trauma (Fig. 42-5). These testes usually function normally but should be placed into the scrotum surgically by age 2 years.
Hypoplastic or Absent Testes
Approximately 8% of children with an empty scrotum have either an absent of shrunken testicle. Although hormones may be involved with this, it is likely that the main cause is the blood supply to the testicle was interrupted. Often this is because the blood vessels to the testicle became twisted during development and the blood supply was cut off. This is called torsion. The scrotum on the side where this occurs is usually underdeveloped. The vas deferens on the affected side may be present and end blindly in the inguinal canal. A surgical procedure to identify a testicle that lies inside the abdomen or that cannot be felt in the inguinal canal is necessary as total absense of the testicular is uncommon. Although abdominal ultrasound studies and computed tomography (CT) scans may assist in identifying intra-abdominal testes, surgical exploration, usually with laparoscopy, is necessary to establish the diagnosis because dysplastic or intra-abdominal testes may develop a cancer over time. A testicular prosthesis can be inserted into the scrotum for psychological benefit though this is usually not done in childhood.
True Undescended Testes
More than 80% of true undescended testes occur on one side only. Most cryptorchid testes are prevented from reaching the scrotum because the spermatic artery is shorter than normal and will not reach the scrotum. The undescended testis that does not descend into the scrotum spontaneously, with hormone therapy, or after an operation by age 4 years probably will not produce sperm normally. The higher the testis resides above the scrotum, the more abnormal the testes is likely to be. A specific hormonal absence that accounts for cryptorchidism has been difficult to identify. Children with cryptorchidism on both sides are more likely to have a hormonal deficiency than children with the testis in the normal position on at least one side. In most cases if a child has an undescended testicle on one side it will descend into the scrotum by 9 months to one year of age. After the first year of life, true undescent is abnormal, occurring in approximately 1.2% of boys at that age. Damaging influences causing changes in the undescended testis may begin by 9 to 18 months of age though few changes have been noted in children under one year of age. After the second year, the sperm counts decrease significantly, especially if the testicle is in the abdomen. Damage to the testicle may occur from the higher temperature in the abdomen compared with that of the scrotum. A one sided undescended testis is may produce autoantibodies that adversely affect development and function of the normal testis on the opposite side. This may cause the normal testis to be unable to produce sperm normally. If the undescended testis is not placed into the scrotum at an early age, fertility is likely to decrease. Young children who undergo surgical correction of undescended testis (called orchidopexy) subsequently show an increase in the sperm count. This improvement is mainly seen when orchidopexy is performed by age 2 years.
Treatment
Hormone therapy may be beneficial particularly in cases of undescended testicles on both sides of the scrotum. Few reports document reliable benefit for true one sided undescended testes and in these cases surgery is most often recommended. In cases of undescended testes on both sides hormonal therapy may be considered but there are potential side effects to the hormones. High doses and long-term use of human chorionic gonadotropin, the hormone specifically used for these cases, may cause damage to the small tubes carrying sperm in the testicle, early development of sexual characteristics, and early stoppage of bone growth. Combination hormone therapy before orchiopexy enlarges the testis and the spermatic vessels, making the technical repair easier, particularly in children with a small scrotum, and it may promote development of the testicle after repair.
Orchiopexy
The major indications for performing surgery to bring the testicles into the scrotum are to avoid the potential problems with fertility, to reduce the likelihood of the testicle twisting and cutting off its blood supply, to repair a associated hernia, to prevent trauma or pain, to provide easier examination for testicular tumor, and for psychological effect and appearance. Surgically the limiting factor for placement of the testis in the scrotum is the length of the spermatic artery, which is placed under tension when the testis is pulled into the scrotum. Any associated hernia is repaired at the time of the orchidopexy.. The testis is secured in the low scrotum with sutures. The procedure is performed through a hernia incision that is slightly larger than that used to repair a hernia alone. Another small incision has to be made in the scrotum in order to suture the testicle into place. The operation is performed with the patient under general anesthesia, usually on an outpatient basis.
For high undescended testes, several surgical techniques have been used effectively to move the testicles into the scrotum. The Fowler-Stephens operation provides length for the testicle to reach the scrotum by dividing the spermatic artery and veins high in the abdomen. The testis derives its blood supply entirely from the vessels of the vas deferens. This operation is done in 2 stages. The first divides the artery as mentioned and moves the testicle as close to the scrotum as possible. The second stage 1 or 2 years later and moves the testicle the rest of the way into the scrotum. The waiting period allows the small artery associated with the vas to enlarge and potentially provide better blood supply to the testicle. The initial division of the spermatic vessels of intra-abdominal testes can be accomplished laparoscopically.
Currently, laparoscopy is probably the best way to identify the site of an intra-abdominal testis or document absence of a teste in boys with an empty scrotum and testis that cannot be felt on one or both sides. Occasionally an small shrunken testis may be encountered either in the inguinal canal or within the scrotum. In these cases it may be best to remove that testis after confirming that there is a normal testicle on the opposite side. The surgeon may wait until puberty to remove the shrunken or abnormal testes because it may still produce hormones and be of some advantage. If the testis is absent, a scrotal prosthesis can be placed sometime after puberty.
Results
Complications from orchiopexy include injury to the vas (approximately 1%), spermatic vascular injuries leading to testicular shrinkage (1% to 8%), and having the testicle pull back toward the abdomen (5% to 10%). Fertility in patients with uncorrected one sided undescended testis has been reported between 30% and 60%. Fertility in patients with one sided descended testis repaired before age 9 years is near 85%, indicating the importance of early surgical repair. For children with untreated two sided undescended testes, 100% are infertile, although testosterone production is often normal. If orchiopexy for two sided undescended testes is performed in children before age 5 years, 50% are fertile, and 30% have normal sperm counts. Patients who undergo two sided orchiopexy before age 2 years are reported to have greater than 65% fertility, whereas patients repaired after age 13 have approximately 12% fertility.
Malignancy
Approximately 12% of testicular tumors arise in undescended testes. Conversely, 5% of cryptorchid testes may become malignant. A tumor in a cryptorchid testis is 30 to 50 times more likely than in a normal testicle. Atrophic and intra-abdominal testes may have a 200-fold increase in the incidence of tumor. Orchiopexy may not decrease the likelihood of tumor. The average age when a tumor is found is 26 years. Malignant tumors originating from cryptorchid testes include seminoma, teratocarcinoma, embryonal carcinoma, and adult teratoma. The incidence of tumor has been lower in cryptorchid testes placed into the scrotum before age 5 years compared with cryptorchid testes repaired in adolescence. Current belief is that children 14 years or older with a unilateral high undescended testis should undergo ipsilateral orchiectomy rather than orchiopexy because the risk of developing a neoplasm seems to increase directly with age at the time of orchiopexy. Testes in the low inguinal canal that grossly appear normal should be biopsied to determine if dysplasia is present before performing orchiectomy. A close relationship may exist between the development of neoplasm in the testicle and the degree of dystopia. When the testicle is removed or in the case of anorchia, regardless of the patient’s age, a testicular prosthesis should be placed into the scrotum.
The higher the testis resides above the scrotum, the more dysgenetic the morphology. Patients with high testes rarely respond to luteinizing hormone–releasing hormone and human chorionic gonadotropin and should have an orchiopexy by age 2 years. Low testes may descend with hormone treatment at age 2 to 3 years; if not, patients should undergo orchiopexy. Unilateral cryptorchid testes that are dysplastic or located high should be removed before adolescence. The unilateral cryptorchid testis may produce adverse effects on the contralateral descended testis after age 2 years. Fertility in children with unilateral undescent repaired before age 2 years is near normal.
Article and graphics adapted from O'Neill: Principles of Pediatric Surgery. © 2003, Elsevier.