epididymitis

**Definition:** Inflammation of the epididymis (the coiled tube on the posterior testis that stores and matures sperm). Acute if symptoms <6 weeks; chronic if >3 months. Often accompanied by orchitis (epididymo-orchitis).

**Pathophysiology:** Usually ascending infection from the urethra or bladder via the vas deferens. Retrograde reflux of urine can also cause a sterile, chemical epididymitis (heavy lifting/straining, amiodarone-induced).

**Etiology by age/risk group (high-yield):** - Sexually active men <35: Chlamydia trachomatis (most common), Neisseria gonorrhoeae. - Men >35, or those with BPH, urinary obstruction, recent instrumentation/catheterization: coliforms (E. coli), Pseudomonas, Enterobacteriaceae (UTI-type pathogens). - Men who practice insertive anal intercourse: Enteric organisms (E. coli) plus STI pathogens. - Children/prepubertal boys: Usually associated with congenital urogenital anomalies (e.g., ectopic ureter) or reflux. Often sterile or coliform. - Other: Mumps (orchitis, not typically epididymitis), TB (granulomatous, "beaded" vas deferens), Brucella, Candida/Cryptococcus in immunocompromised, amiodarone (noninfectious, drug-induced).

**Clinical features:** - Acute, gradual-onset unilateral scrotal/testicular pain, swelling, erythema, and warmth. The epididymis is tender, possibly indurated and swollen, and may progress to involve the testis. - Dysuria, urethral discharge, urinary frequency/urgency, fever. - Positive Prehn sign (pain relief on scrotal elevation). Note: Its reliability is limited clinically. - Cremasteric reflex is intact (absent in testicular torsion). - Possible reactive hydrocele.

**Diagnosis:** - Clinical diagnosis supported by urinalysis (pyuria), urine culture, and NAAT for chlamydia/gonorrhea (urine or urethral swab). - Gram stain of urethral discharge: ≥2 WBC per oil-immersion field suggests urethritis (gonococcal if gram-negative intracellular diplococci). - Scrotal Doppler ultrasound: increased blood flow to the epididymis (hyperemia), whereas torsion shows decreased/absent flow. Use when torsion cannot be excluded.

**Differential:** Testicular torsion (surgical emergency; sudden severe pain, high-riding testis with horizontal lie, absent cremasteric reflex, negative Prehn, "bell-clapper" deformity, peak ages adolescents), orchitis, torsion of appendix testis ("blue dot sign"), inguinal hernia, testicular tumor, hydrocele, trauma.

**Treatment (CDC-based):** - Likely chlamydia/gonorrhea (<35): Ceftriaxone 500 mg IM single dose + doxycycline 100 mg PO BID x10 days. - Enteric organisms likely (insertive anal intercourse): Ceftriaxone + levofloxacin 500 mg daily x10 days (or ofloxacin). - Older men or those with enteric organisms only (no STI risk): Levofloxacin or ofloxacin for 10 days. - Supportive care: Scrotal elevation, NSAIDs, rest, ice. - Treat/test sexual partners for STI-associated cases; abstain from sex until therapy is completed and symptoms resolve.

**Complications:** Abscess formation, testicular infarction, infertility (especially with bilateral involvement), chronic epididymitis/pain, and fistulae.

**Board pearls:** - Young sexually active man with gradual unilateral scrotal pain + dysuria/urethral discharge → chlamydial epididymitis. - Sudden pain in adolescent with absent cremasteric reflex → torsion; go straight to surgery/Doppler. - Older man with BPH and UTI → E. coli epididymitis. - Beaded vas deferens or chronic nodular epididymis → TB. - Fluoroquinolones are avoided for gonorrhea in the US because of resistance, hence ceftriaxone. - Amiodarone causes a noninfectious epididymitis (typically bilateral, dose-related).