Hydrocele is the accumulation of fluid between one of the layers of the testicle (vaginal tunic) and the scrotum of one or both testicles. It can be congenital (affects babies at birth) or acquired, i.e. secondary to infections, trauma, tumors, surgeries on the testicle, etc.
In most cases the hydrocele is presented as an inflammation of the testicle, not painful or causing mild discomfort. In itself, it is not a cause of sterility but certain cases, such as those caused by an infection, can reduce the reproductive capacity.