Undescended Testicles – Testis, Maldescensus Testis, and Cryptorchidism

The testicles are part of the male reproductive system. They play a crucial role in sperm production and are therefore essential for fertility.

Undescended testicles is an embryonic malformation in which one or both testicles fail to descend into the scrotum. They are often found instead in the groin or abdominal cavity. The medical term for undescended testicles is maldescensus testis.

The cause of undescended testicles is not yet fully understood. Possible causes include hormonal imbalances or anatomical barriers that prevent the testicle or testicles from descending from the abdomen into the scrotum. There are different types of undescended testicles.

Inguinal undescended testicle

In the case of an inguinal testicle, the testicle is stuck in the upper groin area and cannot make its way into the scrotum. An inguinal testicle is the most common form of undescended testicle that requires treatment.

Intra-abdominal testicle

In the case of an abdominal testicle, the descent of the testicle into the scrotum has already stopped within the abdominal cavity.

This form of undescended testicle also requires treatment. Otherwise, it can lead to health problems later in life, such as infertility or even tumors.

Partially descended testicle

A sliding testicle is located just above the scrotum in the groin area. Although the testicle can be moved into the scrotum, it then slides back into the area above the scrotum. This is where the name “sliding testicle” comes from. The reason for this sliding back is a spermatic cord that is too short.

Pendulous testicle

Although a pendulous testicle is generally located in the scrotum, it can be pulled upward by certain reactions or reflexes. This involves the contraction of a specific muscle, the cremaster muscle.

Cold temperatures or sexual arousal can be factors that contribute to the contraction of this muscle.

In cryptorchidism, one or both testicles are not located in the scrotum © Maryna Vladymyrska | AdobeStock

Undescended testicles can have genetic causes as well as be influenced by external factors. Genetic causes include, for example, a defect in the genetic material. This defect can also lead to other malformations. These can then make it difficult or even completely prevent the testicle from descending properly into the scrotum.

External factors may include, for example, smoking or alcohol consumption during pregnancy. However, other factors such as environmental toxins or the mother’s diabetes can also contribute to undescended testicles.

Additional risk factors for the development of undescended testicles include

• a birth weight of less than 2.5 kg,
• premature birth,
• placental insufficiency, i.e., inadequate supply of oxygen and nutrients to the fetus and reduced human chorionic gonadotropin (HCG) secretion (e4),
• low maternal estrogen levels.

In addition, certain medications taken during pregnancy, such as acetaminophen, can cause undescended testicles. Studies have shown evidence of such a link (“weakly significant associations”). However, further research is needed to prove this link beyond a doubt.

Undescended testicles are the most common genital malformation in male infants: 3% of newborns and 30% of premature infants are diagnosed with undescended testicles. For this reason, doctors pay close attention to this condition even in newborns.

To determine the type of undescended testicle, the doctor performs several examinations. Ultrasound can be used to objectively assess the position of the testicle in cases where it is not clinically palpable (i.e., cannot be felt under the skin).

If no testicle is visible on the ultrasound, a laparoscopic testicular search should be performed.

Boys diagnosed with undescended testicles should undergo treatment as soon as possible. Without treatment, those affected may be infertile as adults. The temperature in the abdominal cavity or in the groin area is slightly higher than in the scrotum.

In cases of unilateral undescended testicle, however, the other testicle may be able to compensate for the absence of the undescended testicle.

Other risks may include testicular tumors. The likelihood of a tumor increases with untreated undescended testicles.

Undescended testicles should be treated as soon as possible. The goal is to complete treatment by the time the child is 12 months old. For premature infants, the corrected age applies.

Sometimes the testicle moves spontaneously into the correct position within the first six months of life. Treatment of the affected testicle should therefore not begin until after six months.

After the 6th month, hormone therapy with

• GnRH alone (over 4 weeks) or
• hCG (over 3 weeks) or
• as combination therapy with GnRH followed by hCG

. This involves administering hormones that are also responsible for the normal descent of the testicle during pregnancy. 

According to the guidelines, hormone therapy has two goals:

• to guide the undescended testicle back to its anatomically correct position.
• to stimulate germ cell maturation and proliferation (cell division) in order to improve fertility.

Unfortunately, except in cases of cryptorchidism, hormone therapy is not very promising in many cases: Statistically speaking, hormone therapy is successful in only one out of every five patients. In addition, various side effects may occur, such as pubic hair growth or enlargement of the genitalia.

For all other forms, therefore, surgical treatment is the primary approach. Various procedures are used for this purpose, such as

• laparoscopic surgery for undescended testicles or
• open surgery for undescended testicles.

There are several methods available for this.

The sooner the surgery is performed, the lower the risk of complications.

In rare cases, testicular atrophy may occur as a complication after surgery. In this condition, the testicle shrinks due to tissue loss.

A recurrence, in which the testicle retracts back into the groin, is far less common.

Even after a successful surgery, parents should consult a doctor if they notice certain changes—such as the testicles growing back. For this reason, it is advisable for patients to learn early on to watch for such signs. The urologist is the doctor of choice for undescended testicles and their associated symptoms.

Undescended testicles should be detected and treated early to avoid long-term consequences. The most common forms of undescended testicles include pendulous testicles, sliding testicles, and bilateral undescended testicles. Often, the testicles are located in the abdominal cavity or outside the scrotum and may not be palpable. The condition usually originates embryonically during pregnancy when the testicle fails to descend into its proper position. Some testicles may still spontaneously descend into the scrotum during the first six months of life, while others remain permanently outside the body.

The pediatrician therefore regularly checks the position of the testicles in the child—especially shortly after birth. A hormone test can determine whether the testicles are underdeveloped or if there are hormonal causes. If undescended testicles persist, treatment usually involves an orchidopexy. During this procedure, the spermatic cord is carefully mobilized and the testicle is secured in the scrotum. In some cases, a second surgery is necessary after an initial correction.

Untreated secondary undescended testicles increase the risk of infertility and testicular cancer as the child gets older. Testicles are particularly sensitive to temperature changes even before birth, as they are less well protected outside the scrotum. Cold or physical contact can also affect the position of the testicles. The goal of any treatment is to permanently preserve testicular function and to position the testicles in a stable, anatomically correct location.

What is undescended testicles?
Undescended testicles refer to a condition in which the testicles are located outside the scrotum. The medical term is maldescentus testis or cryptorchidism. In this condition, the testicle may remain in the inguinal canal, in the groin, or within the abdominal cavity.

What are the different types of undescended testicles?
Types of undescended testicles include pendulous testicles, sliding testicles, inguinal testicles, and abdominal testicles. In cases of bilateral undescended testicles, both testicles are affected. Some testicles can be felt, while others cannot.

When should undescended testicles be treated?
Treatment for undescended testicles should ideally take place within the first year of life. If the testicles do not descend into the scrotum on their own, surgery or hormone therapy is usually recommended. The risk of future complications increases significantly after a child’s first birthday.

How is surgery for undescended testicles performed?
The procedure is called orchidopexy. During the procedure, the testicle is moved into the scrotum and the spermatic cord is secured. The goal is to ensure the testicles are properly positioned in the scrotum to preserve testicular function.

What are the risks of untreated undescended testicles?
Untreated undescended testicles can impair testicular function. As a child gets older, the risk of testicular cancer and infertility increases. Testicles located in the abdominal cavity or outside the body are particularly sensitive to heat and hormonal changes.