It is estimated that 3 percent to 4 percent of full-term boys and 21 percent of male infants born preterm are born with this feature. Usually, only one testicle is affected, but 10 percent of all cases, both testicles are affected.
Undescended testicle (UDT) is also known as cryptorchidism. It is one of the most common endocrine problems affecting newborn males, and it is the most common genital condition that is identified at birth. It is more likely to affect boys who are born prematurely.
Whether it affects one or both testicles, cryptorchidism generally corrects itself within a few months, but sometimes surgery is needed to relocate the testicle, or testis, into the scrotum.
What is cryptorchidism?
Boys born preterm are more likely to have an undescended testicle.
The word "cryptorchidism" comes from the Greek words "kryptos," meaning "hidden," and "orchis" which means "testicle."
The scrotum is a small pouch, or sac, of skin that hangs behind the penis. Inside the scrotum is a pair of testicles, the oval-shaped sex organs that form part of the male reproductive system. The testicles produce sperm and testosterone, a hormone that plays a key role in male sexual development.
During gestation, the testicles form in the abdomen and gradually descend into the scrotum around the 8th month.
In cryptorchidism, the testicles do not descend or do not appear.
Undescended testicles may be palpable or unpalpable.
A palpable, undescended testicle can be felt during a physical examination. About 80 percent of cases are palpable. The testicle is usually located at the end of the inguinal canal, a channel that carries the spermatic cord towards the penis and scrotum in males.
There are three main types of unpalpable undescended testicle:
- Abdominal: the least common location for an undescended testicle is in the abdomen
- Inguinal: The testicle has moved into the inguinal canal, but has not moved far enough down to be detected by touch
- Atrophic or absent: The testicle is either very small, or it has never formed.
An unpalpable undescended testicle cannot be felt during a physical examination.
The following risk factors are linked to cryptorchidism:
- Premature birth, and the earlier the birth, the higher the risk
- Infants whose birth weight is below 5.5 lb have double or triple the risk
- Down syndrome and other conditions that can slow fetal growth
- Exposure to pesticides or hormone-disrupting chemicals, like DES
- Family history of problems of genital development
- Tobacco consumption during pregnancy by the mother.
Consuming more than five alcoholic drinks a week during pregnancy has also been linked to temporary cryptorchidism.
In the early stages, all fetuses have identical reproductive precursors, regardless of sex. In other words, they have structures that can develop into either male or female reproductive organs.
The child receives a pair of sex chromosomes from its mother and father. Sex chromosomes are a pair of DNA molecules. The chromosomes will be XX if the fetus is female and XY if male.
As the fetus develops, the XY gene promotes the development of the testis. The testes produce hormones that then promote the growth of the male reproductive tract, and these prevent female development from occurring.
It is thought that the problems of absent or undeveloped testicles happen at this stage.
Abnormal genital development may also stem from androgen insensitivity syndrome, a genetic disorder in which XY fetuses do not respond to male hormones, or androgens, such as testosterone.
In this case, the infant is born looking like a girl, with a short, blind, pouch vagina but with no uterus, ovaries, or fallopian tubes. The testes are present in the abdomen or the inguinal canal.
In most cases of undescended testicle, a combination of genetics, maternal health, and some environmental factors are thought to disrupt the hormones, physical changes, and nerve activity that is involved in the development of the testicles.
However, the exact cause is unknown.
To diagnose an undescended testicle, the baby is usually placed in a warm bath. This helps him to relax, and it expands the skin around the scrotum, making it easier to carry out the examination.
If the testicle is not in the scrotum and cannot be felt, a pediatric urologist will probably carry out further tests. In about 20 percent of cases, the missing testicle is not discovered until the child is no longer a baby.
These may include:
- Ultrasound scan to locate the testicle, if it is in the groin
- MRI scan with a contrast agent that is injected into the bloodstream, to show whether the testicle is in the groin or abdomen
- Laparoscopy involves a tube with a tiny video camera that is inserted through a small incision in the abdomen. Corrective surgery may be possible during this procedure
- Open surgery may be necessary in rare, complicated cases, to explore directly inside the abdomen.
If both testes are undescended, a genetic test to determine the sex chromosomes (XX, XY) may be recommended.
Some female babies have external male genitals, or ambiguous genitalia. Tests that may be carried out to check for undescended testicles include ultrasound, to see if there are any ovaries, blood and urine tests to check hormone levels, and a sex-related gene test.
In around half of all patients with cryptorchidism, the testicle will descend on its own within 3 months. However, in 1 to 2 of every 100 cases it does not descend by the time a child is 6 months old, and surgery is needed.
Orchidopexy or orchiopexy is a surgical procedure that is commonly used to free an undescended testicle and implant it into the scrotum.
It is usually done between the ages of 6 to 18 months. It should definitively be performed before a child is two years old, as delaying the operation may increase the long-term risk of developing testicular cancer or infertility.
The testicles reside in the scrotum, because they need to be at a lower temperature than the rest of the body to produce sperm; if they are not at this temperature, it will impair sperm production.
The surgeon makes a small incision in the abdomen and uses small surgical instruments to move the testicle down the inguinal canal and place it in the scrotum, using a second incision.
The inguinal canal is normally sealed to stop the testicle from going back up.
Most patients return home on the same day as the surgery.
To develop and function properly, the testicles need an environment that is 2 to 3 degrees lower than normal body temperature. The scrotum offers this environment.
If the testicle has not descended, its environment will be too hot. This can lead to testicular cancer or fertility problems, due to low sperm count and poor sperm quality.
Other complications of undescended testicle include a higher incidence of testicular cancer, the reasons for which remains unclear. This affects fewer than 1 percent of men.
Testicular torsion can occur, in which the spermatic cord is twisted. The spermatic cord contains nerves, blood vessels and tubes that carry semen to from the testicle to the penis. Left untreated, the individual can lose the affected testicle.
If the testicle is in the groin, pressure from the public bone can damage it. An inguinal hernia can results if a portion of the intestines pushes into the groin.
Damage to the vas deferens can be a complication resulting from the surgery. The vas deferens is the tube that connects the testicle to the urethra.