A hydrocele (HI-droe-seel) is a type of swelling in the scrotum that occurs when fluid collects in the thin sheath surrounding a testicle. Hydrocele is common in newborns and usually disappears without treatment by age 1. Older boys and adult men can develop a hydrocele due to inflammation or injury within the scrotum.
A hydrocele usually isn't painful or harmful and might not need any treatment. But if you have scrotal swelling, see your doctor to rule out other causes.