Epididymitis & Orchitis
Epididymo-orchitis is an infection of the epididymis (± testis) — and the single most important decision is age-driven, because age predicts the organism and therefore the antibiotic.
The big picture
Epididymo-orchitis is an infection of the epididymis (± testis) — and the single most important decision is age-driven, because age predicts the organism and therefore the antibiotic: young, sexually active men get STIs; older men get the enteric organisms of a UTI. The second non-negotiable is that you must be sure it is not testicular torsion, which is the surgical emergency that mimics it.
The framework: the <35 vs >35 age split for etiology → exclude torsion (Doppler) → age-targeted antibiotics → supportive care and follow-up.
Mechanism pathway
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Diagnostic algorithm
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Board traps
Age drives the bug: <35 sexually active → chlamydia/gonorrhoea; >35 (and children) → enteric (E. coli).
Always exclude torsion — duplex Doppler; if in doubt, explore (don't rely on Prehn sign).
Young/STI regimen: ceftriaxone IM + doxycycline 100 mg BID × 10 days (+ treat partner).
Older/enteric regimen: a fluoroquinolone (levofloxacin 500 mg daily × ~10 days).
Cover enteric organisms in men who practise insertive anal intercourse, regardless of age.
Orchitis is often viral (mumps) — supportive care; may impair fertility.