• Inflammation (infectious or noninfectious) of the epididymis resulting in scrotal pain and swelling, induration of the posterior epididymis, involvement of the adjacent testicle, and possible hydrocele formation
  • Acute epididymitis: scrotal pain for <6 weeks
  • Chronic epididymitis: scrotal pain for ≥6 weeks
  • Epididymitis with involvement of the testis is named epididymo-orchitis.
  • Classification: infectious (bacterial, viral, fungal, parasitic) versus noninfectious (chemical, traumatic, autoimmune, idiopathic, industrial, vaso-epididymal reflux syndrome)
  • System(s) affected: reproductive


  • Predominant age: generally younger, sexually active men or older men with UTIs and bladder outlet obstruction (e.g., benign prostatic hyperplasia [BPH])
  • Predominant sex: male only

Pediatric Considerations
Epididymitis is found to be the most common cause of acute scrotal pain in prepubertal boys—more common than testicular torsion.


  • Common (600,000 cases annually in the United States) (1)
  • 1 in 1,000 adult males per year
  • 1.2 in 1,000 boys aged 2 to 13 years per year (2),(3)


Etiology and Pathophysiology

  • Infectious epididymitis
    • Retrograde passage of urinary bacteria from the prostate or urethra to the epididymis via the ejaculatory ducts and the vas deferens; rarely, hematogenous spread
    • Causative organism is identified in 80% of patients and varies according to patient age.
  • Noninfectious epididymitis
    • Often, no etiology is found; however, can be instigated by trauma, autoimmune disease, or vasculitis
    • Likely secondary to reflux of sterile urine causing a chemical inflammation
    • Can develop as sequelae of strenuous exercise with a full bladder when urine is pushed through internal urethral sphincter (located at proximal end of prostatic urethra) or prolonged periods of sitting
    • Reflux of urine through orifice of ejaculatory ducts at verumontanum may occur with history of urethritis/prostatitis because inflammation may produce rigidity in musculature surrounding orifice to ejaculatory ducts, holding them open.
    • Exposure of epididymis to foreign fluid may produce inflammatory reaction within 24 hours.
  • <14 years of age
    • Cause largely unknown, although likely from anatomic abnormalities resulting in urine reflux such as vesicoureteral reflux, ectopic ureter, or anorectal malformation (rectourethral fistula)
    • May also result from postinfectious syndrome from Mycoplasma pneumoniae, enterovirus, or adenovirus
    • Henoch-Schönlein purpura may present as acute scrotal pain.
  • 14 to 35 years of age
    • Usually Chlamydia trachomatis, Neisseria gonorrhoeae, or Mycoplasma genitalium in sexually active males
    • With anal intercourse, likely enteric pathogens (e.g., Escherichia coli)
  • >35 years
    • Commonly enteric bacteria but occasionally Staphylococcus aureus or Staphylococcus epidermidis
    • In elderly men, often with distal urinary tract obstruction, BPH, UTI, or catheterization
    • Tuberculosis (TB), if sterile pyuria, nodularity of vas deferens (hematogenous spread), and recent infection. TB is the most common granulomatous disease affecting the epididymitis.
    • Sterile urine reflux after transurethral prostatectomy
    • Granulomatous reaction following BCG intravesical therapy for bladder cancer
  • Amiodarone may cause a dose-dependent noninfectious epididymitis; usually resolves with decreasing drug dosage (<200 mg/day)
  • Syphilis, blastomycosis, coccidioidomycosis, and cryptococcosis are rare causes, but brucellosis can be a common cause in endemic areas.

Risk Factors

  • UTI
  • Prostatitis
  • Indwelling urethral catheter
  • Urethral instrumentation or transurethral surgery
  • Urethral or meatal stricture
  • Transrectal prostate biopsy
  • Prostate brachytherapy (seeds) for prostate cancer
  • Anal intercourse
  • High-risk sexual activity
  • Strenuous physical activity
  • Prolonged sedentary periods
  • Bladder obstruction (BPH, prostate cancer)
  • HIV-immunosuppressed patient
  • Severe Behçet disease
  • Presence of foreskin
  • Constipation
  • Increased intra-abdominal pressure (due to frequent physical strain)
    • Military recruits, especially who begin physically unprepared
    • Laborers; restaurant kitchen workers
    • Full bladder during intense physical exertion

General Prevention

  • Safer sexual practices
  • Mumps vaccination
  • Antibiotic prophylaxis for urethral manipulation
  • Early treatment of prostatitis/BPH
  • Vasectomy or vasoligation during transurethral surgery
  • Avoid vigorous rectal exam with acute prostatitis.
  • Emptying the bladder prior to physical exertion
  • Physically conditioning the body prior to engaging in regular intense physical exertion
  • Treat constipation.

Commonly Associated Conditions

  • Prostatitis/urethritis/orchitis
  • Hematospermia
  • Constipation
  • UTI

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