Hydrocele is a condition when clear fluid accumulates in the scrotum. It is often not identified at first because it is mostly painless. Commonly seen in infants, hydrocele occurs when the fluid from the abdomen flows down to the scrotum when the gap between the two fails to close. However, the reason why such gap should fail to close in some infants or why the liquid should not dry up by itself is not clearly known. Hydrocele is also caused among adult men. The reasons may be many including physical injury as well as side effects of some more serious health conditions.

Each testicle is enclosed in a thin membrane called the tunica vaginalis. Sometimes, clear fluid accumulates within this thin membrane resulting in a swollen scrotum. This condition is known as hydrocele.

Types of hydrocele and incidence

Before discussing the causes in detail, it is necessary to know that there are two types of hydrocele. These are:

  1. Simple hydrocele is that where the gap between the abdominal cavity and the scrotum has closed up but the fluid has not dried.
  2. Communicating hydrocele is that condition where the gap between the abdomen and the scrotum remains open. As a result, fluid continues to drain from the abdomen to the scrotal area.

According to statistics provided by the Department of health, UK, 0.069% of hospital consultation in 2002-03 dealt with hydrocele and of them, 99% required admission. Of these, 9% were admitted on emergency basis.

Generally, one in every ten male infants has symptoms of hydrocele but most of the cases are resolved spontaneously. Very rarely, the symptoms are also seen in female infants.

Causes of hydrocele

The causes of hydrocele may be described as follows:

  • During embryogenesis, when the foetus is being formed, the testis forms in the abdomen and then descends through the inguinal canal.
  • During this descent, it drags down a part of the diverticulum of the peritoneum with it. This part is known as processus vaginalis.
  • In normal course of events, the processus vaginalis fuses shut after the descent is complete and the testis reaches the area of the scrotum. The fluid within it dries up. The membrane remains covering the testis as the tunica vaginalis.
  • In some cases, the procesus vaginalis may not close completely. The communication remains open with the abdominal cavity. At such times, the fluid from the abdomen keeps draining into the cavity of the scrotum. This is known as a communicating hydrocele.
  • If the closure of the processus vaginalis is incomplete, the fluid may stop draining, but it is not absorbed by the body. This results in simple congenital hydrocele. Clear fluid accumulates in the scrotal cavity. In most cases, this condition heals spontaneously within a year of birth.
  • It is not clearly known or understood why the processus vaginalis should not close properly.

Apart from the infants, hydrocele is also observed among young adults and sometimes in men aged over 40. The causes in these cases may be as follows:

  • Trauma to the scrotum region.
  • Ischemia
  • Infection, mostly sexually transmitted
  • Tumour in the testicular region.

There are some other causes which are rarer, but the case may be more serious.

  • It may be caused as a side effect of filariasis.
  • It is also a documented side effect of ipsilateral renal transplantation.
  • In adult males, if no other reasons are found, possibility of testicular cancer, testicular torsion or strangulated hernia also needs to be investigated.

It is not clearly known why hydrocele affects some male infants and not others. Here are a few risk factors that have been identified.

  1. It is more common in premature or low birth weight infants.
  2. It is related to intrascrotal pathology.
  3. Lymphatic obstruction may be a cause
  4. Inguinal hernia is another possibility.
  5. Surgery or trauma can also cause hydrocele.