Most Common Causes of Epididymitis
The most common causes of epididymitis vary by age group, with sexually transmitted infections (STIs) predominating in younger men and urinary tract pathogens in older men. 1
Age-Based Etiology
Men Under 35 Years
- Chlamydia trachomatis - most frequent cause 1, 2
- Neisseria gonorrhoeae - second most common STI cause 1
- Escherichia coli - particularly in men who are insertive partners during anal intercourse 1
Recent evidence confirms this pattern, with one study finding chlamydia (12.3%) more common than gonorrhea (3.1%) in men under 35 diagnosed with epididymitis 3.
Men Over 35 Years
- Gram-negative enteric organisms (especially E. coli) - most common cause 1
- These infections are typically associated with:
- Urinary tract infections
- Recent urinary tract instrumentation or surgery
- Anatomical abnormalities of the urinary tract 1
Clinical Presentation Patterns
Epididymitis typically presents with:
- Gradual onset of unilateral testicular pain
- Swelling and tenderness of the epididymis
- Often accompanied by urethral symptoms (dysuria, frequency)
- Urethritis (which may be asymptomatic) commonly present with STI-related cases 1
Important Diagnostic Considerations
When evaluating epididymitis, critical tests include:
- Gram-stained smear of urethral exudate for urethritis and gonococcal infection
- Nucleic acid amplification testing for N. gonorrhoeae and C. trachomatis
- Urinalysis and urine culture for enteric organisms
- Examination of first-void urine for leukocytes 1
Special Populations
- Men who practice insertive anal intercourse: Higher risk of epididymitis caused by enteric organisms 2
- Post-instrumentation: Higher risk of coliform bacteria causing epididymitis 1
- Children under 14: Often caused by reflux of urine into ejaculatory ducts, though etiology is less well established 2
Clinical Pitfalls
Failure to distinguish from testicular torsion: Torsion is a surgical emergency that occurs more frequently in adolescents and presents with sudden onset of severe pain 1
Inadequate testing: Studies show only about 50% of men diagnosed with epididymitis are tested for gonorrhea and chlamydia 3, potentially leading to missed diagnoses and complications
Overlooking non-infectious causes: Chronic epididymitis may have non-infectious etiologies that require different management approaches
Delayed treatment: Untreated acute epididymitis can lead to infertility and chronic scrotal pain 2
By understanding the age-specific patterns of epididymitis etiology, clinicians can better target diagnostic testing and empiric treatment to improve outcomes and reduce complications.