Undescended testicle (cryptorchidism) is a testicle that hasn't moved into its proper position in the bag of skin hanging behind the penis (scrotum) prior to the birth of a baby boy.

What is it?

Undescended testicle (cryptorchidism) is a testicle that hasn't moved into its proper position in the bag of skin hanging behind the penis (scrotum) prior to the birth of a baby boy.

About 2 to 5 percent of baby boys are born with one or two undescended testicles. An undescended testicle is more common among baby boys born prematurely, or before 37 weeks. It's rare for boys with cryptorchidism to have two undescended testicles.

For most boys born with one or two undescended testicles, the problem corrects itself within the first few months of life. If your infant has an undescended testicle that doesn't correct itself, surgery can usually be used to relocate it into the scrotum.


Testicles form in the abdomen during fetal development. During the last couple of months of normal fetal development, the testicles gradually leave the abdomen, pass through a tube-like passageway in the groin (inguinal canal) and descend into the scrotum.

If your son has an undescended testicle, that process was stopped or delayed in some stage of development. Therefore, you won't see or feel a testicle where you would expect it to be in the scrotum.


The exact cause of an undescended testicle isn't known. A combination of genetics, maternal health and other environmental factors may disrupt the hormones, physical changes and nerve activity that influence the development of the testicles.

Risk factors

Low birth weight and premature birth are the best understood risk factors that may increase the likelihood of undescended testicle in a newborn. Other risk factors are not as well understood. Conditions that may increase the risk include:

  • Low birth weight
  • Premature birth
  • Family history of undescended testicle or other problems of genital development
  • Conditions of the fetus that can restrict growth, such as Down syndrome or an abdominal wall defect
  • Alcohol use by the mother during pregnancy
  • Cigarette smoking by mother or exposure to secondhand smoke
  • Diabetes in the mother — type 1 diabetes, type 2 diabetes or gestational diabetes
  • Parents' exposure to some pesticides


In order for testicles to develop and function normally, they need to be slightly cooler than normal body temperature. The scrotum provides this cooler environment. Until a boy is 3 or 4 years old, the testicles undergo changes that affect how well they function later.

An undescended testicle isn't in a cooler environment. This might increase the risk of complications later in life. These complications include:

  • Testicular cancer. Testicular cancer usually begins in the cells in the testicle that produce immature sperm. What causes these cells to develop into cancer is unknown. Men who've had an undescended testicle have an increased risk of testicular cancer.
  • Fertility problems. Low sperm counts, poor sperm quality and impaired fertility are more likely to occur among men who have had an undescended testicle.

Other complications related to the abnormal location of the undescended testicle include:

  • Testicular torsion. Testicular torsion is the twisting of the spermatic cord, which contains blood vessels, nerves and the tube that carries semen from the testicle to the penis. This painful condition cuts off blood to the testicle. If not treated promptly, it may result in the loss of the testicle. An undescended testicle increases the risk of testicular torsion.
  • Trauma. If a testicle is located in the groin, it may be damaged from pressure against the pubic bone.
  • Inguinal hernia. An undescended testicle may be associated with an inguinal hernia. If the opening between the abdomen and the inguinal canal is too loose, a portion of the intestines can push into the groin.


Your doctor can easily determine that a testicle hasn't descended into the scrotum. The goal of further examination is to locate the position of the testicle and monitor changes in its position. If the testicle is in the groin, your doctor may be able locate it by touch. If it can't be felt (nonpalpable), then he or she will likely refer you to a pediatric urologist for further tests. About 20 percent of undescended testicles are nonpalpable.

If your son has a nonpalpable testicle, the paediatric urologist may order one or more of the following procedures:

  • Ultrasound. An ultrasound is a noninvasive device that uses sound waves to create images of internal structures of the body. An ultrasound may enable the pediatric urologist to locate a nonpalpable testicle, particularly if it's located within the groin.
  • Magnetic resonance imaging (MRI) with a contrast agent. MRI is a technology that uses a magnetic field and radio waves to create images of soft tissues in the body. A contrast agent is a safe "dye" injected into the bloodstream that can improve the imaging capability of the procedure. This procedure may enable your pediatric urologist to locate a testicle in the groin or abdomen.
  • Laparoscopy. This procedure is generally considered the best choice for locating a nonpalpable undescended testicle. Laparoscopy uses a tiny video device connected to a tube that a surgeon inserts through a small incision in your son's abdomen. Images appear and can be enlarged on a video screen. Surgical correction of the undescended testicle may be done during the same procedure.
  • Open surgery. Direct exploration of the abdomen through a larger incision may be necessary in a small number of more complicated cases.

Other diagnostic issues

If your infant has two nonpalpable undescended testicles, your doctor may order tests to determine the sex of your child. The "absent" testicles may, for example, be because your child is genetically a female but has external male genitals. This condition of unclear biological sex is called ambiguous genitalia, or intersex. Tests to assess the possibility of ambiguous genitalia include:

  • Measurements of various hormone levels in blood and urine
  • Analysis of your baby's sex-related genes
  • Ultrasound investigation for female sex organs (ovaries)