What are the causes of epididymitis?

Causes of Epididymitis

The primary causes of epididymitis vary by age group, with sexually transmitted infections being the predominant cause in younger men and urinary tract pathogens being more common in older men. 1, 2

Age-Based Etiology

Men Under 35 Years

• Sexually Transmitted Infections:

  • Chlamydia trachomatis - most common pathogen 1
  • Neisseria gonorrhoeae - second most common 1
  • These typically cause urethritis (often asymptomatic) that ascends to the epididymis 1

• Special Population - Men Who Practice Insertive Anal Intercourse:

  • Escherichia coli and other enteric organisms 1, 3
  • These sexually transmitted enteric infections occur via direct spread during anal intercourse 1

Men Over 35 Years

• Urinary Tract Infections:
  • Gram-negative enteric organisms (e.g., E. coli, Pseudomonas) 1, 4
  • Associated with:
    • Urinary tract abnormalities 5
    • Recent urinary tract instrumentation or surgery 1
    • Bladder outlet obstruction 3
  • Mechanism: Retrograde flow of infected urine into ejaculatory ducts and vas deferens 5

Children (Under 14 Years)

• Non-sexually Transmitted:
  • Reflux of urine into ejaculatory ducts is considered the most common cause 3
  • Congenital urinary tract abnormalities may predispose to infection

Less Common Causes

• Viral Causes:

  • Mumps virus (primarily causing orchitis that may spread to epididymis) 5

• Fungal and Mycobacterial Causes:

  • More common in immunocompromised patients, especially those with HIV 1
  • Tuberculosis can cause epididymitis (tuberculous epididymitis) 1

• Non-infectious Causes:

  • Chemical inflammation from reflux of sterile urine
  • Trauma
  • Autoimmune conditions

Clinical Presentation and Diagnosis

Typical presentation includes:

• Unilateral testicular pain and tenderness
• Palpable swelling of the epididymis
• Possible hydrocele formation
• May be accompanied by urethritis symptoms (dysuria, urinary frequency) 2, 3

Important Differential Diagnosis

• Testicular Torsion: Surgical emergency that must be ruled out, especially in adolescents
  • More common with sudden onset of severe pain
  • More frequent in patients without evidence of inflammation/infection 1

Diagnostic Approach

Based on age and risk factors:

1. Urethral evaluation:

   • Gram-stained smear of urethral exudate
   • Culture or nucleic acid amplification test for N. gonorrhoeae and C. trachomatis

2. Urine studies:

   • First-void urine for leukocytes
   • Culture and Gram stain of uncentrifuged urine for bacteria

3. Additional testing as indicated:

   • Syphilis serology and HIV testing when appropriate 1, 2

Treatment Implications

Understanding the causative organism is critical for proper treatment:

• Young men (<35): Ceftriaxone plus doxycycline to cover both gonorrhea and chlamydia 1, 6
• Older men (>35): Fluoroquinolones (ofloxacin or levofloxacin) to cover enteric organisms 1, 2

Untreated epididymitis can lead to serious complications including infertility and chronic scrotal pain, making prompt and appropriate treatment essential 3.