Synonyms and Related Terms: Filarial hydrocele, defect in tunica vaginalis of scrotum, communicating hydrocele, congenital hydrocele, pediatric hydroceles, indirect inguinal hernias, noncommunicating hydrocele, hydrocele of the cord, late-onset hydroceles, adult hydroceles.

The term 'hydro'- means 'fluid' and 'cele' is 'swelling'.

In short, Hydrocele is a swelling due to the abnormal collection of clear fluid. This term is usually confined to the testis and this occurs only in males.

Filarial hydrocele is common in endemic areas of tropics and sub-tropics. It is caused by filarial worms Wuchereria bancrofti and Brugia malayi and it is estimated that almost 1 billion people in the world are at risk of exposure to these worms.

The testis in the male is similar to the ovary in the female and both these are referred to as the gonads. The gonads secrete hormones and are responsible for the development of male and female attributes and body characteristics.

The testis is located in a bag like structure called scrotum. Three layers of tissue cover the testis. The outermost layer is called the tunica vaginalis (tunica means 'cover'). This layer in turn has two membranes called the parietal (outer) and the visceral (inner).

Normally a small amount of 'lubricating' fluid' is present between these two layers to allow the testes to move freely. Excessive collection of fluid between these two layers results in a hydrocele.

Hydrocele as such does not produce symptoms until it enlarges to a large size. Sometimes treatment may be advised to prevent complications.