A hydrocele is a fluid-filled sack in the scrotum.

Processus vaginalis; Patent processus vaginalis

Hydroceles are common in newborn infants.

During normal development, the testicles descend down a tube from the abdomen into the scrotum. Hydroceles occur when this tube does not close. Fluid drains from the abdomen through the open tube. The fluid builds up in the scrotum, where it becomes trapped. This causes the scrotum to swell.

Hydroceles normally go away a few months after birth, but they may worry new parents. Sometimes, a hydrocele may occur with an inguinal hernia.

Hydroceles may also be caused by:

• Fluid around the area (this type of hydrocele is more common in older men)
• Inflammation or injury of the testicle or epididymis

The main symptom is a painless, swollen testicle, which feels like a water balloon. A hydrocele may occur on one or both sides.

During a physical exam, the health care provider usually finds a swollen scrotum that is not tender. Often, the testicle cannot be felt because of the fluid around it. The size of the fluid-filled sack 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 (transillumination) through the swollen part of the scrotum. If the scrotum is full of clear fluid, the scrotum will light up.

An ultrasound may be done to confirm the diagnosis.

Hydroceles may make it more difficult to do testicular self-exams, which help detect testicular cancer early.

Hydroceles are usually not dangerous. They are usually only treated when they cause infection or discomfort.

Hydroceles from an inguinal hernia should be fixed with surgery as quickly as possible. Hydroceles that do not go away on their own after a few months may need surgery. A surgical procedure called a hydrocelectomy is often performed to correct a hydrocele.

Simple hydroceles in children usually go away without surgery. In adults, hydroceles usually do not go away of their own. If surgery is needed, it is an easy procedure that usually has an excellent outcome. Sometimes, your doctor may use a small needle to remove fluid from the hydrocele. However, the fluid usually returns.

Complications may occur from hydrocele treatment.

Risks from hydrocele surgery may include:

• Blood clots
• Infection
• Injury to the scrotum

Call for an appointment with your health care provider if you have symptoms of hydrocele (to rule out other causes of a testicle lump).

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

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Wampler SM, Llanes M. Common scrotal and testicular problems. Prim Care. 2010. 37(3):613-626.

Kavoussi PK, Costabile RA. Surgery of the scrotum and seminal vesicles. In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 37. 

Barthold JS. Abnormalities of the testes and scrotum and their surgical management.In: Wein AJ, ed. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 132.