A hydrocele (HI-droe-seel) is a fluid-filled sac surrounding a testicle that causes swelling in the scrotum. Hydrocele is common in newborns and usually disappears without treatment during the first year of life. 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. However, if you have scrotal swelling, see your doctor to rule out other causes.