Hydroceles are common in newborn infants.

During a baby's development in the womb, the testicles descend from the abdomen through a tube into the scrotum. Hydroceles occur when this tube does not close after the testicle moves through it. Fluid drains from the abdomen through the open tube and gets trapped in the scrotum. This causes the scrotum to swell.

Most hydroceles go away a few months after birth. Sometimes, a hydrocele may occur with an inguinal hernia.

Hydroceles may also be caused by:

• Buildup of the normal fluid around the testicle. This may occur because the body makes too much of the fluid or it does not drain well. (This type of hydrocele is more common in older men.)
• Swelling or injury of the testicle or epididymis.

The main symptom is a painless, round-oval shaped swollen scrotum, which feels like a water balloon. A hydrocele may occur on one or both sides. However, the right side is more commonly involved.

You will have a physical exam. Your health care provider will find that the scrotum is swollen, but not painful to the touch. Often, the testicle cannot be felt because of the fluid around it. The size of the fluid-filled sac can sometimes be increased and decreased by putting pressure on the abdomen or the scrotum.

If the size of the fluid collection changes, it is more likely to be due to an inguinal hernia.

Hydroceles can be easily seen by shining a flashlight through the swollen part of the scrotum. If the scrotum is full of clear fluid, the scrotum will light up.

You may need an ultrasound or CT scan to confirm the diagnosis.

Hydroceles are not harmful most of the time. They are treated only when they cause infection or discomfort.

Hydroceles from an inguinal hernia should be fixed with surgery as soon as possible. Hydroceles that do not go away on their own after a few months may need surgery. A surgical procedure called a hydrocelectomy (removal of sac lining) is often done to correct the problem. Needle drainage is an option, but the fluid will come back.

Simple hydroceles in children often go away without surgery. In adults, hydroceles usually do not go away on their own. If surgery is needed, it is an easy procedure with very good outcomes. After surgery, a hydrocele can sometimes reoccur.

Risks from hydrocele surgery may include:

• Blood clots
• Infection
• Injury to the scrotum
• Loss of the testicle
• Long-term (chronic) pain
• Continuous swelling

Contact your provider if you have symptoms of hydrocele. It is important to rule out other causes of a testicular lump.

Pain in the scrotum or testicles is an emergency. If you have pain and your scrotum is enlarged, seek medical help right away to prevent the loss of the testicle.

Processus vaginalis; Patent processus vaginalis

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Updated by: Kelly L. Stratton, MD, FACS, Associate Professor, Department of Urology, University of Oklahoma Health Sciences Center, Oklahoma City, OK. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.