A collection of fluid connected with the testis or spermatic cord. When there is no obvious cause, it is classified as primary: such hydrocoeles are usually large and tense, and are commonly found in middle-aged and younger men, presenting as a large, painless scrotal swelling. Congenital hydrocoeles may occur in infants, when they are often associated with a hernial sac. Hydrocoele of the cord is rare. Secondary hydrocoele is generally smaller and lax; it is usually secondary to a tumour or inflammation of the underlying testis or epididymis.