A hydrocele is a painless swelling in the scrotum that occurs when fluid collects in the thin layer of skin surrounding a testicle.
It is common in newborn males and usually disappears without treatment within the first year of life.
In older males, a hydrocele can have one of several different causes, including injury or infection.
Diagnosis is usually straightforward, and there is often no need for treatment. In this article, learn more about hydroceles, including their symptoms and when to see a doctor.
A hydrocele is a collection of fluid in the membrane of the testis that causes a swelling in the scrotum.
Females can also experience a hydrocele along the canal of Nuck, but it is very rare.
About 10% of newborn males have a hydrocele, which usually disappears before the age of 1 year.
The swelling can occur on one or both sides of the scrotum. It does not cause pain but may be uncomfortable, particularly when the swelling is significant.
Usually, hydroceles do not cause any pain, and the only symptom is a swollen scrotum.
However, in adults, hydroceles can be uncomfortable. The greater the amount of fluid in the hydrocele, the heavier the scrotum feels. Some people find the swelling more uncomfortable in the morning than in the evening.
If sudden scrotal pain or swelling occurs, especially after an injury to the scrotum, it is important to get medical help straight away.
These symptoms can stem from restricted blood flow in a twisted testicle (testicular torsion), which requires immediate treatment.
There are two types of hydrocele: communicating and noncommunicating.
These hydroceles form in infants when the inguinal ring closes, but fluid remains in the membrane of the testicles. The body usually absorbs the fluid within a year.
Rarely, the inguinal ring remains open, allowing fluid to pass back and forth between the abdomen and the membrane of the testicles. Doctors call this a communicating hydrocele. The scrotal swelling can change size, depending on a person’s activity levels and the amount of fluid present.
The cause of a hydrocele depends on a person’s age.
When a male fetus is growing during pregnancy, the testicles develop near the kidneys in the abdomen. By the end of a full-term pregnancy, they move down to their usual position in the scrotum.
To allow the testicles to descend, a muscle lining opens in the scrotum (the inguinal ring), forming a canal or sac.
Once the testicles have moved into their usual position, the inguinal ring closes. If the ring stays open or reopens, fluid can pass from the belly to the scrotum through this canal, and this causes a hydrocele.
Sometimes, babies are born before the testicles have descended, increasing the chances of a hydrocele developing.
In older males, if the inguinal ring has not closed up or it reopens, a communicating hydrocele can form.
Hydroceles in adult males have several other possible causes, including:
A hydrocele is unlikely to be painful, but it can cause an uncomfortable feeling of heaviness in the scrotum.
A hydrocele is not usually dangerous and will not affect fertility. In rare instances, it might link to an underlying testicular condition, such as an infection, tumor, or inguinal hernia.
People should seek out a diagnosis from a doctor to rule out any other conditions.
When a person with swelling in the scrotum seeks treatment, the doctor will first ask questions to help determine the likely cause.
The doctor will perform a physical exam, which will include feeling the scrotum to confirm the location and extent of the swelling.
A hydrocele lies in front of or below the testicle. The doctor will want to know whether the scrotum feels tender during the exam.
They might also check to see whether light passes through the swelling in the scrotum. This test is called transillumination.
If the swelling is fluid filled, like a hydrocele, light will pass through it. A solid mass, such as a tumor, would not allow light to pass through.
Transillumination can be very helpful in allowing doctors to work out the cause of scrotal swelling, but some other steps can help them make a definite diagnosis.
For example, a doctor may want to order another investigation, such as an ultrasound scan, if they have any doubt about the underlying cause of the swelling.
In rare cases, exploratory surgery might be the only way to determine what issue is responsible for this symptom.
Most babies and infants with a hydrocele will not require any treatment, as the condition will resolve over time.
Parents and caregivers should check the scrotum now and then and contact their doctor if the swelling becomes very large, or if the infant is in pain.
For people with very large and uncomfortable hydroceles, surgery to remove them might be the best option.
Another treatment option is to drain the hydrocele using needle aspiration. In this procedure, a doctor inserts a long needle into the sac to draw out the fluid. They may then inject chemicals into the hydrocele to stop it refilling with fluid (sclerotherapy). This treatment is best for adults at risk of complications during surgery.
Hydroceles are very common in newborn males and usually disappear within a year.
The most common cause is fluid traveling from the abdomen and collecting in the tissue surrounding one or both testicles.
In adult males, swelling in the scrotum has many possible causes, including inflammation from infection or injury.
Most hydroceles, in both infants and adults, disappear without the need for medical intervention. In rare cases, doctors might need to perform surgery or aspiration to drain the fluid.