Hydroceles are acquired or congenital serous fluid collections 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, hydroceles appear as simple fluid, unless complicated by infection or haemorrhage.
Hydroceles can be diagnosed at any age, with congenital hydrocele being more common in children.
Most hydroceles are acquired and present with progressing painless scrotal mass. During the physical examination, hydrocele characteristically transilluminates when evaluated with a light source. They can become painful if infected (see pyocele).
There are two main subtypes of congenital hydrocele:
- communicating hydrocele
- spermatic cord hydrocele 1,2
In the communicating type, fluid collects around a patent processus vaginalis which failed to successfully obliterate.
The spermatic cord hydrocele is further subdivided into:
- encysted type (spermatic cord cyst): no communication with the peritoneum or tunica vaginalis
- funicular type (funiculocele): communicates with the peritoneum at the internal ring and doesn't surround the testis
- more common in children and premature infants 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 serous fluid of an uncomplicated hydrocele.
Treatment and prognosis
In infants, most hydroceles (around 90%) resolve spontaneously, and they are thought to result from incomplete obliteration of the processus vaginalis 4. It is important to assess for any associated herniations in these patients.
Imaging differential considerations include
- 1. Bhosale PR, Patnana M, Viswanathan C et-al. The inguinal canal: anatomy and imaging features of common and uncommon masses. Radiographics. 28 (3): 819-35. doi:10.1148/rg.283075110 - Pubmed citation
- 2. Garriga V, Serrano A, Marin A et-al. US of the tunica vaginalis testis: anatomic relationships and pathologic conditions. Radiographics. 2009;29 (7): 2017-32. doi:10.1148/rg.297095040 - Pubmed citation
- 3. Martin LC, Share JC, Peters C et-al. Hydrocele of the spermatic cord: embryology and ultrasonographic appearance. Pediatr Radiol. 1996;26 (8): 528-30. - Pubmed citation
- 4. Naji H, Ingolfsson I, Isacson D et-al. Decision making in the management of hydroceles in infants and children. Eur. J. Pediatr. 2012;171 (5): 807-10. doi:10.1007/s00431-011-1628-x - Pubmed citation
- 5. Christensen T, Cartwright PC, Devries C et-al. New onset of hydroceles in boys over 1 year of age. Int. J. Urol. 2006;13 (11): 1425-7. doi:10.1111/j.1442-2042.2006.01583.x - Pubmed citation
Ultrasound - testicular and scrotal
- ultrasound (introduction)
testicular and scrotal ultrasound
unilateral testicular lesion
- testicular torsion
- testicular rupture
- germ cell tumours of the testis
- sex cord / stromal tumours of the testis
- testicular cyst
- bilateral testicular lesion
- paratesticular lesions
- tubular ectasia of the rete testis
- cystadenoma of the rete testis
- testicular sarcoidosis
- testicular tuberculosis
- spermatic cord
- fibrous pseudotumour of the scrotum
- scrotal leiomyosarcoma
- testicular adrenal rest tumours (TARTs)
- tunica vaginalis testis mesothelioma
- splenogonadal fusion
- unilateral testicular lesion