A hydrocele is a fluid-filled sac surrounding a testicle that results in swelling of the scrotum (the loose skin underneath the penis) according to the Mayo Clinic. The National Institutes of Health (NIH) report they are common in newborns. Children’s Hospital Boston says the fluid typically makes the scrotum look enlarged. They can occur on one or both sides of the scrotum.
A hydrocele can develop in the womb. The Mayo Clinic says normally, the testicles descend from the developing baby's abdominal cavity into the scrotum. A sac accompanies each testicle, allowing fluid to surround the testicles. Typically, each sac closes and the fluid is absorbed. However, if fluid remains after the sac closes, this is called a closed or non-communicating hydrocele. Because the sac is closed, fluid can't flow back into the abdomen. Usually the fluid gets absorbed within a year.
Another type is an open or communicating hydrocele. This happens when the sac doesn’t close and has contact with the abdominal cavity fluids. The Cleveland Clinic says it is caused by the failure of the thin membrane that extends through the inguinal canal and descends into the scrotum to close completely during prenatal development.
NIH says hydroceles may also be caused by inflammation or injury of the testicle or epididymis, or by fluid or blood blockage within the spermatic cord. This condition is more common in older men and often disappears within six months.
Usually the only symptom of a hydrocele is painless swelling of one or both testicles. The Mayo Clinic says adults may experience discomfort from the heaviness of a swollen scrotum.
Hydroceles usually aren’t dangerous and only require treatment if they cause discomfort or embarrassment, or if they are large enough to threaten the testicle's blood supply according to NIH.
Children’s Hospital Boston says if a closed hydrocele hasn’t disappeared by age one or becomes very large, surgery may be needed. Open hydroceles generally require surgery to prevent future complications.
Treatment options include surgical excision called a hydrocelectomy.