Pediatric Hydrocele

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 are the physical features and types hydroceles?

A hydrocele is characterized as a non-painful, soft swelling of the scrotum (one or both sides). The overlying skin is not tender or inflamed. There are two types of hydroceles:

1. communicating, and
   
2. non-communicating.

Communicating hydroceles

Communicating hydroceles are present at birth and occur as a consequence of the failure of the "tail" end of the process vaginalis to completely close off. Peritoneal fluid (free fluid in the abdominal cavity) is thus free to pass into the scrotum in which the process vaginalis surrounds the testicle.
A characteristic feature of communicating hydroceles is their tendency to be relatively small in the morning (having been horizontal during sleep) and increase in size during the day (peritoneal fluid drainage assisted by gravity). Actions which increase intra-abdominal pressure (for example, crying, severe coughing, etc.) will also tend to increase the size of the hydrocele.

Non-communicating hydroceles

Non-communicating hydroceles may also be present at birth or develop as a boy matures. In a non-communicating hydrocele the tail end of the process vaginalis has closed appropriately. The fluid surrounding the testicle is created by the lining cells of the process vaginalis and is unable to either drain or be reabsorbed efficiently and thus accumulates. Since this fluid is walled off, the size of the hydrocele is generally stable and does not reflect intra abdominal pressure.

How are hydroceles diagnosed?

The diagnosis of a hydrocele is generally made clinically. An apt description of a hydrocele surrounding a palpable (something that can be felt) testis would be that of a small water balloon containing a peanut. The differences between communicating and non-communicating hydroceles described above help to support the suspected diagnosis.
A bedside test, transillumination, provides confirmation of the condition. Transillumination involves placing a small light source (commonly an otoscope - the medical device used to examine the ear) against the swollen scrotum. The fluid filled nature of the hydrocele side is distinctly different from the non-involved side of the scrotum. In rare cases either ultrasound or X-ray study of the region may be indicated. In unusual cases where a hydrocele may be a secondary phenomenon to pathologic cause (caused by disease), surgical exploration may be necessary to establish the diagnosis.

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.
Tumor: childhood tumors of the structures contained within the scrotum are more often benign when compared to those of teens and adults. The most common tumor in this latter age range is testicular cancer. As a response to the notoriety of Lance Armstrong's battle with testicular cancer, the recommendation for monthly self-testicular exams (especially for teens and young adults who have a predisposition for this cancer) has found a more receptive audience than in the past.

Hydrocele At A Glance

• While hydroceles may occur in either gender, they are much more common in males.
  
• A hydrocele is a collection of clear fluid in a thin walled sack present in the scrotum.
  
• Hydroceles may be either one sided or occupy both sides.
  
• Hydroceles are painless, soft swellings and may be either present at birth (congenital) or develop later.
  
• A very large majority of hydroceles present at birth resolve spontaneously by one year of age.
  
• Hydroceles that are not congenital or those still present after one year of age generally warrant surgical correction.
  
• There are other conditions that must be considered when evaluating a boy with chronic, non-tender scrotal swelling. These include hernia, varicocele and tumor. Physical examination is very helpful in sorting through these options. Rarely are diagnostic or invasive studies necessary.

REFERENCES:

George W. Kaplin. "Scrotal Swelling in Children." Pediatrics in Review; vol 21, September 2000, 311-314.

Moritz M. Ziegler. "Diagnosis of Inguinal Hernia and Hydrocele." Pediatrics in Review; vol.15, July 1994, 286-298.

UpToDate.com. "Causes of Painless Scrotal Swelling in Children and Adolescents."

UpToDate.com. "Overview of Inguinal Hernia in Children."