Pediatric Surgery, AlSadik Hospital, Qatif, Saudi Arabia
Cryptorchidism is derived from the Greek kρυπτός, kryptos, meaning hidden and ὄρχις, orchis, meaning testicle.
It is defined as the absence of one or both testes from the scrotum (Fig. 24.1).
A clinical photograph showing undescended right testis
Undescended testis was first described in 1786 by Hunter and has been recognized for centuries.
The first surgical orchiopexy was attempted in 1820 by Rosenmerkal.
Annandale in 1877 performed the first successful orchiopexy.
In 1899, Bevan published the principles of testicular mobilization, separation of the processus vaginalis, and repositioning of the testis into the scrotum.
It is considered the most common birth defect of the male genitalia.
It is estimated that about 3 % of full-term and 30 % of premature infant boys are born with at least one undescended testis.
It is also estimated that about 80 % of undescended testes descend by the first year of life and the majority of them descend within the first 3 months of life.
This makes the true overall incidence of undescended testes around 1 %.
About 75–80 % of undescended testes are unilateral.
Cryptorchidism can affect one or both testes and approximately 10 % of cases are bilateral. For unilateral cases the left testicle is more commonly affected
In 80–90 % of cases, an undescended testis can be felt in the inguinal canal; in a minority the testis or testes are in the abdomen or nonexistent (truly “hidden”).
It has been estimated that the incidence of undescended testis in premature male newborns is about 30 %.
The incidence of undescended testes in full-term male newborns is 3–5 %.
This incidence decreases to 0.8 % at 3 months of age as some of these undescended testes will descend to the scrotum spontaneously.
In the United States, the prevalence of cryptorchidism ranges from 3.7 % at birth to 1.1 % from age 1 year to adulthood.
Internationally, the prevalence of cryptorchidism ranges from:
4.3–4.9 % at birth
1–1.5 % at age 3 months
0.8–2.5 % at age 9 months
Siblings of boys with undescended testes are at increased risk for cryptorchidism, with a reported incidence of up to 10 %.
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.
True undescended testicles rarely descend into the scrotum spontaneously after 4 months of age.
Factors that Predispose to cryptorchidism include:
Low birth weight
Small size for gestational age
Maternal exposure to estrogen during the first trimester
Sometimes undescended testes are found incidentally during routine herniotomy in patients with testicular feminization syndrome (Figs. 24.2 and 24.3).
Intraoperative photograph showing bilateral intraabdominal testes in a patient with testicular feminization syndrome
Intraoperative photograph showing a hernia sac containing intraabdominal testis in a patient with testicular feminization syndrome
Early diagnosis and management of the undescended testicle are important to preserve fertility and improve early detection of testicular malignancy.
The recent improvements in surgical technique, including laparoscopic diagnosis and treatment of undescended testes are likely to improve outcomes.
According to the guidelines published by the American Urological Association in May 2014:
Imaging for cryptorchidism is not recommended prior to referral, which should occur by 6 months of age.
Orchiopexy is the most successful therapy to relocate the testis into the scrotum.
Hormonal therapy is not recommended.
Successful scrotal repositioning of the testis may reduce but does not prevent the potential long-term issues of infertility and testis cancer
Appropriate counseling and follow-up of the patient are essential
Undescended testes are known to be associated with complications which include:
Increased risk of testicular germ cell tumors
Undescended testes are known to be associated with inguinal hernia which can be complicated by irreducibility and strangulation
Psychological problems when the boy grows up
Undescended testes are also more susceptible to testicular torsion and subsequent infarction
Undescended testes are more prone to trauma
It has been shown that men who have had an undescended testis have:
Lower sperm counts
Poorer quality of sperms
Lower fertility rates than normal men
The likelihood of subfertility increases in those with bilateral undescended testes and increasing age at the time of orchidopexy.
The risk of subfertility can be reduced by early orchidopexy.
This is one reason why orchidopexy should be done early as early as 6 months of age and not later than 2 years of age.
An increased incidence of epididymal abnormalities in undescended testes also contributes to infertility.
It has been well documented that men with a history of undescended testicle have a higher-than-expected incidence of testicular germ cell cancers. The incidence of testicular cancer among men with an undescended testis is approximately 1 in 1,000 to 1 in 2,500. This is significantly higher than the risk among the general population (1:100,000).
Orchidopexy does not reduce the risk of testicular cancer, but it makes it easier to diagnose it early through testicular self-examination.
About 20 % of testicular tumors in men with unilateral cryptorchidism occur on the side with the normally descended testicle.
Undescended testes have also an increased risk of testicular torsion. Torsion of an intra-abdominal testis may present as an acute abdomen.
Undescended testes are also known to be associated with an inguinal hernia (Patent processus vaginalis) which is repaired at the time of orchidopexy. If an overt hernia is present in association with undescended testis, hernia repair with orchidopexy should be done at the time of diagnosis. This is to avoid the risk of irreducibility and strangulation.
The classification of undescended is based on the physical and operative findings of undescended testes:
True undescended testicles: This can be
Peeping testis at the internal ring
Canalicular or inguinal testes
Undescended testes at the upper scrotum
About one half of nonpalpable testes are found to be intra-abdominal, while the rest represent absent (vanishing) or atrophic testes.
The vanishing testicle is thought to be caused by intrauterine testicular torsion.
Sometimes tissue in the scrotum may be palpable and it feels like an atrophic testis. This should not be taken for granted and sometimes this tissue represents the gubernaculum or a dissociated epididymis and vas deferens, and may coexist with an intra-abdominal testis.
The presence of bilateral nonpalpable testes in a phenotypically male newborn should be taken seriously. The possibility of a genetic female with congenital adrenal hyperplasia and in an older child testicular absence must be kept in mind. These patients should be evaluated including:
Measurements of serum electrolytes, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), müllerian-inhibiting hormone (MIH), and adrenal hormones and metabolites (17-hydroxyprogesterone).
A stimulation test using intramuscular human chorionic gonadotropin (hCG) can be done to check for evidence of testosterone production by the gonads.
Pelvic ultrasound is useful in infants with bilateral nonpalpable testes not only to look for gonads but also to exclude the presence of a uterus.
Ultrasonography, computed tomography or magnetic resonance imaging, are not sensitive or specific enough to detect the majority of intra-abdominal testes and surgical exploration or laparoscopy is required.
24.2 Embryology and Normal Testicular Development and Descent
Embryologically, the testes develop in the abdomen along the gonadal ridge from the primitive (indifferent) gonad. This is under the influence of several male genes.
This occurs at about the sixth week of gestation under the influence of the SRY gene.
The SRY gene is located on the short arm of the Y-chromosome (Yp11.3). It is responsible for initiating sex differentiation by downstream regulation of sex-determining factors.
This involves expression of several genes including WT1, CBX2 (M33), SF1, GATA4/FOG2 is critical to SRY activation.
The SOX9 gene, located on 7q24.3-25.1, is essential for early testis development.
The second step in male sex differentiation involves internal and external genitalia differentiation.
During the third to fifth months of intra-uterine development, the cells in the testes differentiate into testosterone-producing Leydig cells, and anti-Müllerian hormone-producing Sertoli cells. The germ cells become fetal spermatogonia.
The developed testes have two types of cells:
The Leydig cells
The Sertoli cells
The Sertoli cells produce the anti-Müllerian hormone (AMH).
The Leydig cells produce testosterone.
The AMH acts on its receptor in the Müllerian ducts and causes their regression.
Testosterone acts in a critical concentration-dependent and time-dependent manner to induce male sexual differentiation.
Testosterone acts on the androgen receptor in the Wolffian ducts to induce the formation of:
The Leydig cells also produce insulin-like factor 3 (INSL3, relaxin-like factor), which play a role in the descent of testes to the scrotum.
Testosterone is also converted to dihydrotestosterone (DHT) under the influence of 5-alpha reductase enzyme, which acts on the androgen receptor of the prostate and external genitalia to cause its masculinization.
Binding of Testosterone and DHT to androgen receptors is necessary for androgen effect.
The testes remain high in the abdomen until the seventh month of gestation, when they start descending from the abdomen through the inguinal canals into their final position in the scrotum.
It has been proposed that testicular descent from the abdomen into the scrotum occurs in two phases, under control of somewhat different factors.
The first phase:
This involves descent of the testes from the abdomen to the entrance of the inguinal canal.
This phase is under the influence of the anti-Müllerian hormone (AMH).
The second phase:
This involves descent of the testes through the inguinal canal into the scrotum.
This phase under the influence of androgens (testosterone).
It was shown experimentally that androgens induce the genitofemoral nerve to release calcitonin gene-related peptide (CGRP), which causes rhythmic contractions of the gubernaculum that help facilitates testicular descend into the scrotum.
It was also suggested that the testes secret a hormone called descendin which through a paracrine effect help in testicular descent.
In many infants with inguinal testes, further descent of the testes into the scrotum occurs in the first 6 months of life. This is attributed to the postnatal surge of gonadotropins and testosterone that normally occurs between the first and fourth months of life.
Factors that can affect testicular descent include:
Maldevelopment of the gubernaculum
Deficiency or insensitivity to AMH
Deficiency or insensitivity to androgen
Anatomical factors that interfere with testicular descent
Spermatogenesis continues after birth.
In the third to fifth months of life, some of the fetal spermatogonia residing along the basement membrane become type A spermatogonia.
More gradually, other fetal spermatogonia become type B spermatogonia and primary spermatocytes by the fifth year after birth.
Spermatogenesis arrests at this stage until puberty.
24.3 Classification of Undescended Testes
A testis absent from the normal scrotal position can be found any were along the “path of descent” from high in the posterior (retroperitoneal) abdomen, just below the kidney, to the upper part of the scrotum.
In the abdomen: These are not palpable
In the inguinal canal
Just above the scrotum
Retractile testis: A testis that can easily move between the scrotum and inguinal canal.
Ectopic testis: A testis that descended but have “wandered” from the normal path of descent to lie outside the inguinal canal.
In the superficial inguinal pouch
Under the skin of the thigh
In the perineum
In the opposite scrotum
In the femoral canal
Undeveloped (hypoplastic) testis
Severely abnormal (dysgenetic) testis
Vanished testis: This is most likely secondary to intrauterine torsion of testes with infarction and necrosis
Ascent testis: A testis observed in the scrotum in early infancy can occasionally “reascend” (move back up) into the inguinal canal.
Most normal-appearing undescended testis are also normal by microscopic examination, but reduced spermatogonia can be found. The tissue in undescended testes becomes more markedly abnormal (“degenerates”) in microscopic appearance between 2 and 4 years after birth. There is some evidence that early orchidopexy reduces this degeneration.
24.4 Causes of Undescended Testes and Risk Factors
In the majority of undescended testes, no definite cause can be found
Several factors may contribute to the development of cryptorchidism including genetics, maternal health and other environmental factors. These include:
Parents’ exposure to some pesticides
Diabetes and obesity in the mother
Exposure to regular alcohol consumption during pregnancy
Family history of undescended testicle
The use of cosmetics by the mother
Prenatal exposure to a chemical called phthalate (DEHP) which is used in the manufacture of plastics
Exposure to mild analgesics by pregnant mothers
Premature infants and low birth weight infants are known to have a higher incidence of undescended testes.
Intra-abdominal pressure also appears to play a role in testicular descent.
Conditions associated with decreased pressure include:
Prune belly syndrome
Each is associated with an increased risk of undescended testes.
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.
Epididymal abnormalities often accompany undescended testes, but the causal relationship has not been established.
Cryptorchidism occurs at a much higher rate in a large number of congenital malformation syndromes including:
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