I. Overview
An abnormal location where the testis does not move along the normal descent pathway but instead migrates outside the scrotum is called cryptorchidism. During embryonic life, the testis forms next to the middle kidney and descends along the inguinal canal into the scrotum. If this process is faulty, the testis can stagnate anywhere along the normal descent pathway (undescended testis), deviate from the normal descent pathway (ectopic testis), become necrotic or undeveloped (disappearing testis). Simple cryptorchidism is the most common congenital anomaly of the male external genitalia, with an incidence of approximately 1% in term newborns at 1 year of age.
II. Etiology and risk factors.
1. Endocrine factors: Normal hypothalamic-pituitary-gonadal axis is necessary for the descent of the testes. Abnormalities of androgens, estrogens, INSL3, AMH, CGRP, and EGF can affect the normal descent of the testes;
2, Testicular or epididymal dysplasia;
3.Mechanical factors: short spermatic cord, narrow inguinal canal;
4, Genetic factors: Cryptorchidism has the tendency to gather in families. The genetic susceptibility is polygenic and multifactorial;
5.Environmental risk factors: prenatal exposure to environmental endocrine-disrupting factors, such as synthetic estrogens, pesticides, industrial surface activators, plastic additives, etc.
III. Pathology.
Testicular descent is necessary for normal spermatogenesis because normal spermatogenesis requires a scrotal environment that is 2-3 degrees cooler than the internal temperature.
Gross pathology: testicular hypoplasia (small/flat/soft texture)
Histopathology: The histopathology of children with cryptorchidism at 1-2 years of age includes reduced interstitial cells, degeneration of supporting cells, delayed germ cell regression, delayed spermatogonia maturation, impaired primary vein cell formation and reduced total germ cells. The current study shows similar but less severe histopathological changes in the contralateral normal descending testis. Because the interstitial cells are less involved, they can secrete sufficient testosterone to maintain normal male characteristics and sexual performance.
IV. Diagnosis and classification
1.Classification
Palpable: 80%, 60-70% are unilateral, right side is more common
Non-palpable type: 20%, of which 25-50% are peeping testes located at the mouth of the inner ring, 15-40% are completely atrophied testes (disappearance of testes), 10-30% are testes located outside the abdominal cavity and not palpated due to various reasons (obesity, body position, too small testes, uncooperative patients, etc.)
2. Diagnosis
Physical examination is the only way to distinguish between palpable and non-palpable cryptorchidism. Ultrasound, CT, MRI or angiography are of little benefit for diagnosis. A unilateral unpalpable testis with contralateral testicular enlargement usually indicates a missing or atrophic testis, but is not specific and still requires laparoscopic exploration. Diagnostic laparoscopy is currently the only way to diagnose or rule out cryptorchidism of the abdominal type, cryptorchidism of the inguinal type, and testicular disappearance.
IV. Treatment
1.Surgical treatment: the gold standard of cryptorchidism treatment
(1) Age of surgery: Since it is difficult for the testicle to descend on its own at more than 6 months of age, and pathological changes occur in the testicle as early as 12-18 months of age. It is recommended that surgery for cryptorchidism be done after 6 months of life and before 1 year of age, and no later than 18 months of age.
(2) Surgical methods.
Open surgery: mostly used for palpable inguinal type cryptorchidism
Lumpectomy: mostly used for abdominal type cryptorchidism. If the testicle is close to the internal ring and the child is less than 6 years old, free spermatic cord testicular fixation is feasible; if the testicle is far from the internal ring, the child is older and it is estimated that the free spermatic cord cannot lower the testicle into the scrotum, Fowler-Stephen stage I or staged surgery is feasible.
(3) Post-operative complications: testicular atrophy, testicular retraction
2. Reasons why cryptorchidism needs surgical treatment.
(1) Infertility: Cryptorchidism can lead to infertility, which is related to the patient’s treatment age, the type of cryptorchidism and the degree of testicular epididymal development. 90% of men with unilateral undescended testes have parentage (i.e. can have the next generation), and only 33-65% of those with bilateral undescended testes become fathers.
(2) Cancer: The risk of malignancy in cryptorchidism is 3.7-7.5 times higher than in the normal population. 10% of testicular tumors occur in patients with a history of undescended testes, but the chance of testicular tumors in patients with a history of cryptorchidism is still less than 1 in 2000. testicular tumors tend to occur during and after puberty, but tumors have been reported to occur within 10 years of age. The higher the position of the undescended testis, the greater the risk of malignancy. Early testicular fixation can reduce the risk of malignant testicular degeneration. Testicular biopsy at the time of surgery is recommended for patients with combined prune belly syndrome, ambiguous external genitalia, or cryptorchidism at age >12 years.
(3) Inguinal hernia: 90% of patients with cryptorchidism have a combined inguinal hernia.
(4) Risk of testicular torsion: The risk of torsion in the abdominal type undescended testis is greater than in those with normal testicular position and the chance of surgical salvage is low (10%), while torsion in the inguinal type cryptorchidism is uncommon.
(5) Risk of testicular trauma: inguinal cryptorchidism is prone to blunt trauma
(6) Effects on psychology.
3. Hormonal treatment.
(1) The maximum success rate of applying hCG or GnRH for cryptorchidism is 20%: and there is still a possibility of re-rising in these patients after stopping the drug. The higher the testicular position, the lower the success rate of hormone therapy. Hormone therapy before and after surgical treatment may be beneficial in improving the fertility index, but long-term follow-up is still needed, as it has also been shown that hormone therapy can undergo apoptosis of spermatocytes and affect future spermatogenesis. Hormone therapy is still not the standard treatment for cryptorchidism and needs to be individualized according to the patient’s condition.
(2) Patients who are not suitable for hormone therapy: newborns, post-operative undescended testes or ectopic testes, patients with anatomical abnormalities (prune belly syndrome), and patients with normal post-pubertal endocrine function
(3) Side effects of hormone therapy: penile growth, frequent erections, scrotal pigmentation, increased appetite, weight gain, and aggressive behavior, which usually improves when the drug is stopped. Excessive hormone application may lead to premature epiphyseal closure.
V. Prognosis
Unilateral cryptorchidism is fertile, but bilateral cryptorchidism has low fertility. There is an increased risk of testicular tumors in undescended testes, so these patients should be screened during adolescence and beyond.