An enlarged, hyperaemic epididymis (head first) with or without a hyperaemic testis — judged against the other side at the same colour settings, and only after torsion has been positively excluded.
Orient first
- Infection usually starts in the epididymal tail and head and spreads to the testis; isolated orchitis is uncommon outside mumps.
- Hyperaemia is a relative finding: the same colour gain, scale and depth on both sides is the only fair comparison.
- A reactive hydrocele, scrotal wall thickening and a complex collection (abscess) travel with it; testicular ischaemia can follow severe orchitis.
Acquire the study
- High-frequency linear probe, both hemiscrota in one transverse "buddha" view for side-by-side grey-scale and colour Doppler, then each side with spectral Doppler; low-flow settings (low scale, low wall filter).
The manoeuvre
- Transverse view of both testes together: compare size, echo pattern and colour flow at identical settings.
- Epididymis head, body and tail on each side: thickness in mm and colour vascularity relative to the contralateral side.
- Testis: focal hypoechoic areas, heterogeneous texture, and arterial spectral waveform — reversed diastolic flow warns of venous compromise.
- Spermatic cord above the testis: a straight cord, no whirlpool sign — the torsion question is answered here, not at the testis.
- Collections: complex fluid with no internal colour flow is an abscess; note its size in cm.
What confirms it
- Enlarged hyperaemic epididymis relative to the other side, with a normal straight spermatic cord and preserved testicular arterial flow, in a clinical picture of infection.
What licenses you to exclude it
- Symmetric epididymal size and flow at identical settings argues against it — but hyperaemia does not exclude torsion-detorsion, which is also hyperaemic.
The classic misread
- Calling torsion-detorsion "epididymitis" because the flow is increased — look at the cord.
- Asymmetric colour gain producing false hyperaemia on one side.
- Missing the segmental testicular infarct that complicates severe orchitis.