A Hyrdocele is formed in the testes when there is an abnormal build-up of fluid that causes the affected testicle to swell. In some cases, the body can reabsorb the fluid. Even though the condition is painless, the hydrocele may become so large that surgery is needed to remove it. In some cases, an untreated hydrocele can turn into an inguinal hernia.
- Scrotal lumps and inflammation - factsheet, Andrology Australia