At ultrasound, the findings of acute epididymitis include an enlarged hypoechoic or hyperechoic (presumably secondary to hemorrhage) epididymis [Fig. 20a]. 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 [Fig. 20b] is a well-established diagnostic criterion and may be the only imaging finding of epididymo-orchitis in some men.<ref name="MakTzeng2012"/>
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File:Ultrasonography of epididymitis.jpg|[[Doppler ultrasound]] of epididymitis, seen as a substantial increase in blood flow in the left epididymis (top image), while it is normal in the right (bottom image). The thickness of the epididymis (between yellow crosses) is only slightly increased (7 mm).
File:Ultrasonography of orchitis.jpg|Doppler ultrasound of the scrotum of the same case, in the axial plane, showing orchitis (as part of epididymo-orchitis) as a hypoechogenic and slightly heterogenic left testicular tissue (right in image), with an increased blood flow. There is also swelling of peritesticular tissue.
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===Tuberculous epididymo-orchitis===