A hydrocele is a collection of fluid within the tunica vaginalis that surrounds the testes. The tunica vaginalis is a sealed pouch of membrane that surrounds the testes. Originally the tunica vaginalis is part of the peritoneal membrane, but during development of the fetus it becomes separated from the peritoneal membrane and remains in the scrotum, partially covering each testicle.


Simple Hydrocele

Simple hydroceles are common in newborn males. They occurs where fluid is trapped in the tunica vaginalis. Usually this fluid gets reabsorbed over time and the hydrocele disappears.


Communicating Hydrocele

Communicating hydroceles occur where the tunica vaginalis around the testicle is connected with the peritoneal cavity via a pathway called the processus vaginalis. This allows fluid to travel from the peritoneal cavity into the hydrocele, allowing the hydrocele to fluctuate in size.



Hydroceles cause a soft, smooth, non-tender swelling around one of the testes. The swelling will be in front of and below   the testicle. Simple hydroceles remain one size, whereas communicating hydroceles can fluctuating in size depending on the volume of fluid from the peritoneal cavity.

The key features to remember when examining a hydrocele is that they transilluminate with light. To transilluminate the hydrocele, hold a pen torch flat against the skin and watch as the whole thing lights up like a bulb.


Differential Diagnosis

The key differential diagnoses of a scrotal or inguinal swelling in a neonate are:

  • Hydrocele
  • Partially descended testes
  • Inguinal hernia
  • Testicular torsion
  • Haematoma
  • Tumours (rare)



Ultrasound is a useful investigation for confirming the diagnosis and excluding other causes.

Simple hydroceles will usually resolve within 2 years without having any lasting negative effects. Parents can be reassured and followed up routinely. They may require surgery if they are associated with other problems, such as a hernia.

Communicating hydroceles can be treated with a surgical operation to remove or ligate the connection between the peritoneal cavity and the hydrocele (the processus vaginalis).


Last updated January 2020
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