A hydrocele is a common problem due to a collection of excess fluid around a testicle. The testes are surrounded by a fine layer of tissue called the tunica vaginalis. Fluid may accumulate between the testicle and the tunica to cause swelling at almost any age and may follow an injury or infection in the scrotum, or for no apparent reason.
The swelling is painless but there may be some discomfort and the swelling in the scrotum may slowly enlarge to the size of a tennis ball or more. Other cysts and growths can occur in the scrotum including cancer, which may not be painful. These conditions may need to be excluded by an ultrasound scan.
Shining a bright torch through the scrotum in a darkened room (transillumination) can show the fluid filled sac surrounding the testicle.
In infants the problem sometimes settles without treatment, but in adults a needle is used to drain off the fluid. Unfortunately the fluid often re-accumulates and a minor surgical procedure may be necessary to give a permanent cure. There is no permanent damage to the testicle or its function.