Ultrasonography of epididymitis and epididymo-orchitis

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Author: Mikael Häggström [notes 1]

Normal epididymis thickness
Head 10 - 12 mm[1]
Tail 2 - 5 mm[2]


Need for imaging

Imaging is not necessary, but is generally indicated for patients with indeterminate examination, history, or laboratory workup findings.[3]

Choice of modality


Look particularly at the epididymal tail, since this is usually the first affected part in epididymal inflammation (epididymitis). It can then potentially spread to the epididymal body and head, and in 20% to 40 % of cases to the testice (epididymo-orchitis).[4]

At ultrasound, the findings of acute epididymitis include an enlarged hypoechoic or hyperechoic (presumably secondary to hemorrhage) epididymis. Other signs of inflammation such as increased vascularity, reactive hydrocele, pyocele and scrotal wall thickening may also be present. Testicular involvement is confirmed by the presence of testicular enlargement and an inhomogeneous echotexture. Hypervascularity on color Doppler images is a well-established diagnostic criterion and may be the only imaging finding of epididymo-orchitis in some men.[4]

Further workup

If epididymitis is visualized, the scrotum should also be scanned for any potential abscess formation.


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.


  1. Page 221 in: Janice Hickey, Franklin Goldberg (1999). Ultrasound Review of the Abdomen, Male Pelvis & Small Parts . Lippincott Williams & Wilkins. ISBN 9780397516919. 
  2. Chaitali Shah. Acute right epididymitis. Sonoworld.com. Retrieved on 2018-06-26.
  3. Christina B Ching. Epididymitis Workup. Medscape. Updated: Jan 22, 2018
  4. 4.0 4.1 Content originally copied from: Mak, Chee-Wai; Tzeng, Wen-Sheng (2012). Sonography of the Scrotum . doi:10.5772/27586.  from Kerry Thoirs. Sonography., Published: February 3, 2012, under the CC-BY-3.0 license.