What causes a prominent epididymis?

Causes of Prominent Epididymis

The most common causes of a prominent epididymis are infectious epididymitis (primarily from sexually transmitted infections in men under 35 and urinary tract pathogens in older men), followed by non-infectious inflammatory conditions and anatomical variations. 1

Infectious Causes

Age-Specific Pathogens

• Men under 35 years:

  • Sexually transmitted infections (STIs) are predominant 1, 2
  • Chlamydia trachomatis - most common pathogen 1, 2
  • Neisseria gonorrhoeae - second most common pathogen 1, 2
  • Transmission via retrograde propagation through vas deferens 3

• Men over 35 years:

  • Enteric bacteria (coliforms) from urinary tract infections 2, 4
  • Often associated with bladder outlet obstruction causing reflux of urine into ejaculatory ducts 2
  • Escherichia coli is a common pathogen 5

• Children (prepubertal):

  • Reflux of urine into ejaculatory ducts 3
  • Usually not sexually transmitted 3

Risk Factors

• Unprotected sexual intercourse 1
• Urinary tract abnormalities 3
• Bladder outlet obstruction (particularly in older men) 2
• Recent urologic procedures 3
• Insertive anal intercourse (risk for enteric organisms) 2

Non-Infectious Causes

• Trauma to the scrotal area
• Chemical epididymitis (from reflux of sterile urine or medications)
• Autoimmune reactions
• Vasectomy (post-procedure inflammation)
• Anatomical variations (congenital)

Diagnostic Features

Clinical Presentation

• Gradual onset of posterior scrotal pain (unlike the sudden onset in testicular torsion) 1, 4
• Swelling and tenderness of the epididymis 2, 4
• May be accompanied by urinary symptoms (dysuria, frequency) 2
• Testis in normal anatomic position 4
• Positive Prehn sign (pain relief with scrotal elevation) 1
• Present cremasteric reflex 1

Key Diagnostic Tests

• Urethral swab or first-void urine for STI testing (NAAT) 1
• Urinalysis and urine culture 1
• Scrotal ultrasound with Doppler (shows increased blood flow in epididymitis vs. decreased in torsion) 1

Clinical Pearls

• A prominent epididymis with sudden onset of severe pain, absent cremasteric reflex, and high-riding testicle should raise suspicion for testicular torsion, which is a surgical emergency 1
• Untreated epididymitis can lead to infertility and chronic scrotal pain 2
• Up to 40% of patients with epididymitis may develop persistent oligozoospermia or azoospermia 6, 5
• The immune environment of the epididymis varies along its length: the caput (head) has a more tolerogenic environment while the cauda (tail) shows stronger inflammatory responses 6, 5
• This immune distribution explains why infections often affect the cauda epididymis more severely, potentially causing greater damage to sperm function 6, 5

Management Considerations

Treatment should target the likely causative organism based on patient age and risk factors:

• For men under 35 with suspected STI: Ceftriaxone plus doxycycline 1, 2
• For men over 35 or with urinary tract infection: Fluoroquinolones (levofloxacin or ofloxacin) 1, 2
• Partner evaluation and treatment is essential to prevent reinfection 1
• Supportive measures include rest, scrotal elevation, and anti-inflammatory medications 1

Clinical improvement should occur within 3 days of starting treatment; if not, reevaluation of diagnosis and therapy is warranted 1.