There are two types of hydroceles depending on how they form. One type is seen in children, generally shortly after birth. It is caused by a failure of the processus vaginalis to close. Usually, surgery isn't used to treat hydrocele until after two years of age because the processus vaginalis frequently closes by itself if given extra time. In adults, hydroceles develop slowly.
Most hydroceles develop because of blocked lymphatic flow.
Hydroceles also develop after infection, injury, or local cancer tumors. Generally, hydroceles are treated by aspiration of the collected fluid. To do this, a needle is inserted into the scrotum and directed toward the hydrocele. Once there, as much fluid as possible is removed. Hydroceles can reoccur.