What is a hydrocele?
A hydrocele is a scrotal collection of clear fluid ("hydro" = water) in a thin walled sack ("cele" = swelling) that also contains the testicle. Less frequently, due to the common embryological background of male and female gonadal structures, female children or women may also experience a hydrocele. In this case, the sack and connection exist in the labia majora (the outermost and larger of the two labial structures).

Because of less potential concern for complications in females with hydroceles, this article will focus predominantly on the male gender. A hydrocele may involve either one side (unilateral) or both sides (bilateral) of the scrotum

What causes hydroceles?

Embryology
Between the 28th and 36th week of gestation, the testes, associated blood vessels and nerves migrate from the upper posterior abdominal wall adjacent to the kidneys to the lower abdominal cavity and through a tunnel (inguinal canal) into the scrotum. As each gonad exits the pelvic region through the inguinal canal into the scrotum, it is preceded by a thinly lined "sack" called the process vaginalis. Once the testes and associated structures have entered the scrotum, the trailing end of the process vaginalis generally closes off, completely isolating the contents of the abdominal cavity and obstructing their passage into the inguinal canal or scrotum.

Should this closure be incomplete and the communication narrow, free fluid in the abdominal cavity (peritoneal fluid) may seep into and through the process vaginalis and collect in the scrotum forming a hydrocele. If the connection is larger and a portion of the small intestine migrates out of the abdominal cavity into the inguinal canal and/or scrotum, a hernia has developed

What is the treatment for hydroceles?
In 95% of congenital (present at birth) hydroceles, the natural history is one of gradual and complete resolution by one year of age. For those lasting longer than one year or for those non-communicating hydroceles that manifest after the first year, surgical repair is indicated since these rarely resolve spontaneously

What are other non-tender scrotal swelling conditions?
The differential diagnosis (list of possibilities) of chronic non tender scrotal swellings (besides hydroceles) includes:

Hernia:-  A hernia involves the introduction of a segment of the small intestine into the inguinal canal. A sign of a hernia in the small intestinal region is swelling in the groin alone, or may also include the scrotum on the same side. Many complain of an "ache" or "sense of fullness" during this time. If the small intestine spontaneously slides back into the abdominal cavity or if a physician reduces it, the patient is generally referred to a surgeon for closure of the inguinal canal as a preventative move to preclude a repeat experience.

If the small intestine is trapped and cannot be reduced, this is a surgical emergency and the patient will be brought to the operating room in order to avoid intestinal swelling and subsequent limiting of blood flow to the region, and consequent possible death of the trapped bowel tissue.

Varicocele:- A varicocele represents engorgement of the testicular veins and clinically has been likened to a "bag of worms". While it is a relatively rare finding in the preadolescent, approximately 20% of late teens and adult men have been found to have a varicocele. More common on the left side of the scrotum, the varicocele characteristically "deflates" when the male reclines, and becomes engorged due to gravity when standing.

In the older teen and adult, varicoceles generally require no specific management other than observation. In a younger male, if the varicocele becomes painful, or there is an associated size decrease in the same sided testicle, evaluation with a doctor specializing in urology conditions (urologist) should be sought.