Classification of testes falling under the umbrella term “cryptorchidism” includes: intra-abdominal, canalicular, superficial inguinal pouch, ectopic, ascending, vanishing, and absent testis.
Orchidopexy is an elective operative procedure best done in the first 6 months of life.
Laparoscopic orchidopexy is best reserved for both the diagnosis and treatment of intraabdominal testes, unilateral or bilateral, or for the high canalicular inguinal canal testes. Conventional open orchidopexy is best applied to the palpable superficial inguinal ring area testis or for the testis with a symptomatic inguinal hernia.
Testicular descent embryologically is best described by the Hutson 2-phase model. In step one, the abdominal phase (8-15 weeks gestation) is under the influence of MIS; the second inguinoscrotal phase (26-40 weeks gestation) is under androgen stimulation.
Cryptorchidism means hidden or obscure testes and is generally synonymous with undescended testes. Ectopic testis defines a condition caused by an abnormally implanted gubernaculum, wherein the testis has descended from the abdominal cavity and settled in the suprapubic area, the thigh, or the perineum instead of the scrotum (a true ectopic testicle is a very rare condition). Orchidopexy (synonymous: orchiopexy) describes the surgical fixation of the testis in the scrotum and is commonly used to describe the mobilization and fixation of an undescended testis within its respective scrotal compartment.
The primitive gonad begins as coelomic epithelium on the medial aspect of the mesonephros during the fifth week of fetal life. At 7 to 8 weeks of gestation, the primordial germ cells migrate from the embryonic yolk sac to the gonadal cords. Under the influence of SRY (the sex-determining region of the human Y chromosome), which is the testis-determining factor, male differentiation is “switched on.” Leydig cells formed from interstitial tissue start secreting testosterone around day 60, and Sertoli cells, under the influence of the follicle stimulating hormone (FSH), start secreting Müllerian inhibiting substance (MIS). MIS enlarges the gubernaculum, induces involution of the ipsilateral Müllerian structures, and increases the number of androgen receptors on the Leydig cell membrane. Testosterone primes the genitofemoral nerve and is responsible for differentiation of the Wolffian duct. The genitofemoral nerve releases the neurotransmitter calcitonin gene related peptide (CGRP) which produces rhythmic gubernacular contractions, and controls migration of the gubernaculum and testes. In the fetus, testosterone shows an initial surge between 12 and 16 weeks of gestation. Later, decreased maternal human chorionic gonadotropin (hCG) and increased maternal estrogen decrease fetal testosterone levels. After birth, decreased maternal estrogens are responsible for the second surge of testosterone, which is seen at around 60 days of life. Hence, most testes which are not descended at birth would descend by 3 months of life.
Several factors have been recognized as important for normal testicular descent: endocrine, mechanical, and neural. In 1985, Hutson proposed a biphasic model for testicular descent. The first phase ...