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Hydroceles can be acquired or congenital serous fluid collection within layers of the tunica vaginalis surrounding a testis. They are the most common form of testicular enlargement, and present with painless enlargement of the scrotum. On all modalities, hydrocoeles appear as simple fluid, unless complicated by infection or haemorrhage. 

Clinical presentation

Most hydrocele are acquired and present with progressing painless scrotal mass. Characteristically, hydrocele transilluminates when evaluted with light source during physical examination. However, hydroceles can be secondarily infected (see pyocele).


Hydrocele can be diagnosed at any age, with congenital hydrocele being more common in children.



There are two subtypes of congenital hydrocele 1-2 :

  • encysted type with no communication with the peritoneum or tunica vaginalis, also called spermatic cord cyst.
  • funicular type which communicates with the peritoneum at the internal ring and doesn't surround the testis. This type is also called funiculocele. They are more frequently encoutered in children and premature infant 2.
Acquired aetiology

Radiographic features


Ultrasound is the first modality usually used to evaluate hydroceles. It presents as a simple fluid collection surrounding the testis. It is avascular on Doppler evaluation. It may contain septations, calcifications and cholesterol 2.

A funiculocele is a sub type of hydrocele, however, it doesn't surround the testis. They can also appear larger with straining (valsalva) 2. It may contain fibrous adhesions, giving a beaded appearance to the spermatic cord (pachyvaginalitis) 3.

The encysted subtype shows no communication with the peritoneum and it usually only involves the spermatic cord.


On MRI, signal characteristics of the hydroceles are :

  • T1: low signal
  • T2: high signal

This represents the simple serous fluid component of the hydrocele.


In infants most hydroceles (around 90%) resolve spontaneously and their are thought to result in incomplete obliteration of the processus vaginalis 4. It is important to assess for any associated herniations in these patients.

Differential diagnosis

Imaging differential considerations include

Rarely, a scrotal tunica cyst and a scrotal mesothelioma can look like hydrocele. It is usually simple to distinguish them from hydroceles.

See also

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