Merck Manual

Please confirm that you are a health care professional



(Undescended Testes)


Ronald Rabinowitz

, MD, University of Rochester Medical Center;

Jimena Cubillos

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Feb 2019| Content last modified Feb 2019
Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Topic Resources

Cryptorchidism is failure of one or both testes to descend into the scrotum; it is typically accompanied by inguinal hernia. Diagnosis is by examination, sometimes followed by laparoscopy. Treatment is surgical orchiopexy.

Cryptorchidism affects about 3% of term infants and up to 30% of preterm infants; 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.


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).


Undescended testes may cause subfertility and are associated with testicular carcinoma, mainly in the undescended testis and particularly with intra-abdominal malposition. However, in patients with one undescended testis, 10% of cancers develop on the normal side. In untreated cases of intra-abdominal testes, testicular torsion may occur, manifesting as an acute abdomen. Almost all neonates who present with an undescended testis at birth also have an inguinal hernia (patent processus).


Undescended testes are almost always idiopathic. About 10% of cases are bilateral; suspicion should be high for female virilization caused by congenital adrenal hyperplasia in phenotypic boys with bilateral, nonpalpable testes at birth (especially if associated with hypospadias).

Symptoms and Signs

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).


  • 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.

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.


  • Surgical repair

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

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 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 a descended testis).

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

  • Treatment is surgical repair.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Also of Interest


View All
Overview of Coarctation of the Aorta
Overview of Coarctation of the Aorta
3D Models
View All
Cystic Fibrosis: Defective Chloride Transport
3D Model
Cystic Fibrosis: Defective Chloride Transport