Hydroceles are acquired or congenital serous fluid collection between the layers of the tunica vaginalis surrounding a testis or spermatic cord. 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. 

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

Most hydrocele are acquired and present with progressing painless scrotal mass. During physical examination, hydrocele characteristically transilluminates when evaluted with light source. They can become painful if infected (see pyocele).

There are two main subtypes of congenital hydrocele:

  • a communicating hydrocele
  • a spermatic cord hydrocele 1-2.  

In the communicating type fluid collects around a patent processus vaginalis, it having failure to successfully obliterate.

The spermatic cord hydrocele is further subdivided into:

  • 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

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

Communicating, infantile and vaginal hydroceles will be seen intimately surrounding the adjacent testicle. In contrast, spermatic cord hydroceles such as funicular hydrocele (funiculocele) and encysted hydrocele will not surround the testis, rather being found along the spermatic cord.

Hydroceles can also appear larger with straining (Valsalva Manoeuvre) 2. They may contain fibrous adhesions, giving a beaded appearance to the spermatic cord (pachyvaginalitis) 3.

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.

Imaging differential considerations include

Rarely, a scrotal tunica cyst or scrotal mesothelioma can look like hydrocele. They are usually easily distinguishable from hydroceles.

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Article information

rID: 18628
System: Urogenital
Section: Pathology
Tag: refs
Synonyms or Alternate Spellings:
  • Hydrocele
  • Hydrocoele
  • Hydrocoeles
  • Hydroceles
  • Scrotal hydrocele
  • Scrotal hydroceles
  • Scrotal hydrocoele
  • Scrotal hydrocoeles

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Cases and figures

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    Case 1: spermatic cord cyst
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    Case 2: right hydrocele
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    Case 3: large hydrocele
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    Case 4: orchiitis with secondary hydrocele
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     Case 5
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    Encysted hydrocel...
    Case 6: encysted hydrocele
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     Case 7
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     Case 8
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    Case 9: right hydrocele on CT
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    Case 10: encysted hydrocele in an infant
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