A hydrocele is a soft, painless swelling in the scrotum that is due to a build-up of fluid in the double-layered membrane that partially surrounds each testis.
The condition is most common in infants and older men. In most cases, there is no apparent cause, although occasionally a hydrocele may be associated with infection, inflammation, or injury of the testis or, rarely, it may be associated with testicular cancer.
A hydrocele in an infant usually clears up by itself. In older children and adults, treatment to drain the fluid may be advised if a hydrocele is large or troublesome. Treatment may also be needed for any underlying cause that is identified.