A hydrocele is a painless buildup of watery fluid around one or both testicles that causes the scrotum or groin area to swell. This swelling may be unsightly and uncomfortable, but it usually is not painful and generally is not dangerous. Although hydroceles are common in newborns, they can also occur at any age in later life.
Older boys and adult men can develop a hydrocele due to inflammation or injury within the scrotum.
About 10% of newborn male infants have a hydrocele, which often clears up without any particular treatment within the first year of life. Hydroceles occur in only about 1% of adult men.