Merck Manual

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(Undescended Testes)


Ronald Rabinowitz

, MD, University of Rochester Medical Center;

Jimena Cubillos

, MD, University of Rochester School of Medicine and Dentistry

Reviewed/Revised Aug 2022
Topic Resources

Cryptorchidism is failure of one or both testes to descend into the scrotum; in younger children, it is typically accompanied by inguinal hernia. Diagnosis is by testicular examination, sometimes followed by laparoscopy to look for testes that cannot be felt on examination. Imaging studies are rarely indicated. Treatment is surgical orchiopexy.

Cryptorchidism affects about 3% of term infants and up to 30% of preterm infants Preterm Infants An infant born before 37 weeks of gestation is considered preterm. In 2021 in the United States, 10.48% of births were preterm ( 1), and in 2018, 26.53% of births were early term (significantly... read more . About 10% of cases are bilateral. Two thirds of undescended testes spontaneously descend within the first 4 months of life. Thus, about 0.8% of male infants require treatment.

Eighty percent of undescended testes are diagnosed at birth. The remainder are diagnosed during childhood or early adolescence; these are usually caused by an ectopic gubernacular attachment and become apparent after a somatic growth spurt.

Pathophysiology of Cryptorchidism

Normally, the testes develop at 7 to 8 weeks gestation and remain cephalad to the internal inguinal ring until about 28 weeks, when they begin their descent into the scrotum guided by condensed mesenchyme (the gubernaculum). Onset of descent is mediated by hormonal (eg, androgens, mullerian-inhibiting factor), physical (eg, gubernacular regression, intra-abdominal pressure), and environmental (eg, maternal exposure to estrogenic or antiandrogenic substances) factors.

A true undescended testis remains in the inguinal canal along the path of descent or is less commonly present in the abdominal cavity or retroperitoneum. An ectopic testis is one that descends normally through the external ring but diverts to an abnormal location and lies outside the normal course of descent (eg, suprapubically, in the superficial inguinal pouch, within the perineum, or along the inner aspect of the thigh).

Complications of cryptorchidism

Etiology of Cryptorchidism

Symptoms and Signs of Cryptorchidism

In about 80% of cases, the scrotum on the affected side is empty at birth; in the remainder of cases, a testis is palpable in the scrotum at birth but appears to ascend with linear growth because of an ectopic gubernacular attachment that restrains it from following the normal “descent” of the scrotum. Inguinal hernia associated with cryptorchidism is rarely symptomatic, but the patent process is often detectable, especially in infants (but less commonly in those with ectopic undescended testes). Rarely, an undescended testis manifests acutely because of testicular torsion.

Diagnosis of Cryptorchidism

  • Clinical evaluation

  • Sometimes laparoscopy

  • Rarely ultrasonography or MRI

All boys should have a testicular examination at birth and annually thereafter to assess testicular location and growth.

Undescended and ectopic testes must be distinguished from hypermobile (retractile) testes, which are present in the scrotum but easily retract into the inguinal canal via the cremasteric reflex. Diagnosis of cryptorchidism is by physical examination; a warm environment, warm examiner’s hands, and a relaxed patient are important to avoid stimulating testicular retraction. If needed, the child can be placed in a frog-leg position to better examine the testes. Lubricating the child's groin or the examiner's gloved hands with soap before the examination can help decrease friction and aid in the localization of the testis.

In patients with a unilateral nonpalpable testis, a descended testis that is larger than expected suggests an atrophic undescended testis; confirmation requires surgical intervention typically via diagnostic laparoscopy to seek an intra-abdominal testis or confirm testicular agenesis. However, scrotal or inguinal exploration is sometimes done if a testicular remnant distal to the internal inguinal ring is suspected.

For bilateral nonpalpable testes, patients in the immediate neonatal period should be evaluated for a possible disorder of sexual differentiation (consultation with a pediatric endocrinologist should be considered). If a disorder of sexual differentiation has been ruled out, laparoscopy is often necessary to identify testes located in the abdomen and then bilateral orchiopexy may be done.

Treatment of Cryptorchidism

  • Surgical repair

For a palpable undescended testis, treatment is surgical orchiopexy, in which the testis is brought into the scrotum and sutured into place; an associated inguinal hernia is repaired if present.

For a nonpalpable undescended testis, abdominal laparoscopy is done; if the testis is present, it is moved into the scrotum. If it is atrophic (usually the result of prenatal testicular torsion), the tissue is removed.

Surgery should be done at about 6 months of age in term infants and at 1 year of age in preterm infants because early intervention improves fertility potential and may reduce cancer risk. Also, the shorter the child, the shorter the distance necessary to place the testis into the scrotum.

No intervention is needed for a retractile testis as long as the spermatic cord length is sufficient to allow the testis to rest in a dependent scrotal position without traction when the cremasteric reflex is not stimulated. Hypermobility usually resolves without treatment by puberty when increased testicular size makes retraction more difficult.

Key Points

  • Cryptorchidism affects about 3% of term infants and up to 30% of preterm infants; two thirds of undescended testes descend spontaneously.

  • Undescended testes may cause subfertility and increase risk of testicular carcinoma (including in the descended testis).

  • Clinical evaluation is usually adequate; imaging is rarely indicated.

  • Treatment is surgical repair.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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