Undescended testis (see also Plate 3-5) is the most common genital anomaly in males, observed in 3% to 4% of U.S. boys at birth. Although most testis descent occurs prenatally, about 50% of undescended testes at birth subsequently descend during the ﬁrst year of life. This condition may be an isolated birth defect (see Plate 3-5) due to failure of abdominal or inguinoscrotal testis descent, or it may be associated with conditions such as androgen insensitivity, Kallmann syndrome, spina biﬁda, Down syndrome, or endocrine disruption. Mechanical causes relate to adhesions, anatomic maldevelopments of the inguinal canal such as hernia uteri inguinalis, abnormalities of the inguinal ring, the mesorchium, the testis vascular supply, or gubernaculum. An actual congenital inguinal hernia is present in almost every case of true undescended testis, with the hernia sac below the testis in the scrotum. This leads to higher complications such as hydrocele formation and torsion in affected boys. Undescended testes are also at higher risk of malignant degeneration; this risk is related to the original location of the cryptorchid testis and is estimated to occur in 1 of 20 intraabdominal testes and 1 of 80 inguinal testes. Finally, it is also clear that both unilaterally and bilaterally cryptorchid men have higher rates of infertility (deﬁned by paternity rates) compared to men with bilaterally descended testes.
In many prepubertal boys a condition termed “retractile testis” or pseudocryptorchidism can be confused with cryptorchidism. Unlike with true undescended testes, retractile testes can be pulled into the scrotum and will remain there for a ﬁnite period of time before drawing upward again. Retractile testes usually descend into normal position before or during puberty. It is controversial whether this condition harbors the same risks as truly cryptorchid testes in terms of infertility and malignant degeneration. In cases of obesity, the testes may be hidden under the mons pubic fat and this can also be confused with cryptorchidism. A gentle examination, helped with moist heat, usually provides enough relaxation to permit manipulation of the testis into the scrotum. The cooling associated with undressing for an examination may prompt a cremaster reﬂex that elevates the scrotum superiorly.
The longer a testis remains undescended, the higher the risk of later malignant degeneration, testis hormonal failure, and infertility. In general, testes that undergo orchiopexy before puberty are less likely to become cancerous later in life compared to those that are repaired after puberty. Whether early orchidopexy reduces later infertility is unproven. Biopsies of crypt- orchid testes at the time of postpubertal orchiopexy typically reveal tubular atrophy, germ cell aplasia (Sertoli cells only), and Leydig cell hyperplasia on histology. The time or critical age after which permanent damage occurs to the undescended testis is unknown. Degeneration within undescended testes is believed to begin as early as 5 to 6 years of age and adults with childhood orchidopexy can show degenerating semen quality and progressive infertility with time. The optimum time for orchidopexy therapy, therefore, is unclear, but most clinicians recommend treatment before 1 year of age in a healthy infant.
Treatment for cryptorchidism includes watchful waiting, hormonal induction, or surgical repair. As a ﬁrst-line treatment, clinicians may often try a short course of intramuscular human chorionic gonadotropin (hCG) to raise testosterone levels and encourage testis descent in inguinal cryptorchidism. hCG may be effective when cryptorchidism is due to hypopituitarism, but in most cases it likely stimulates descent of a testis that would otherwise normally descend. For deﬁnitive therapy, one-or two-stage orchidopexy procedures are performed to reduce the subsequent risk of torsion or inguinal hernia, to bring the at-risk testis into the scrotum for palpability of malignancy and for cosmesis.
Ectopic testis is a testis that descends but in a pathway that deviates from the usual scrotal end point. The most common landing sites for ectopic testes are (1) interstitial, on the oblique muscle; (2) pubopenile; (3) within the femoral triangle; and (4) perineal. Surgical replacement into the scrotum is indicated for proper testis function and to reduce pain or other complications.