What are the clinical, laboratory, and imaging findings of epididymitis?

Clinical Findings of Epididymitis

Men with epididymitis typically present with unilateral testicular pain and tenderness, with palpable swelling of the epididymis and hydrocele usually present 1.

Clinical Presentation

Primary Symptoms

• Unilateral testicular pain and tenderness - the hallmark finding 1, 2
• Palpable epididymal swelling - present in most cases 1
• Hydrocele - commonly develops as inflammation progresses 1, 2
• Scrotal erythema and swelling - particularly in severe cases 3

Distinguishing Clinical Features

• Prehn sign: Pain relief when elevating the testes over the symphysis pubis suggests epididymitis rather than testicular torsion 4
• Gradual onset: More insidious presentation compared to the sudden onset of testicular torsion 4
• Associated urethritis: Often present but frequently asymptomatic, especially in sexually transmitted cases 1

Age-Related Patterns

• <35 years: Most commonly caused by C. trachomatis or N. gonorrhoeae 1
• >35 years: More likely due to Gram-negative enteric organisms associated with urinary tract infections 1
• Pediatric cases: Occur predominantly in prepubertal period (ages 7-12), often with negative urine tests 5, 6

Laboratory Findings

Urethral Evaluation

• Gram stain of urethral exudate: >5 polymorphonuclear leukocytes per oil immersion field indicates urethritis 1
• Nucleic acid amplification testing: For N. gonorrhoeae and C. trachomatis on intraurethral swab or first-void urine 1

Urine Studies

• First-void urine examination: Check for leukocytes if urethral Gram stain is negative 1
• Urine culture: Positive in only 11% of pediatric cases and minority of adult cases 3, 5
• Important caveat: Normal urinalysis does NOT exclude epididymitis, particularly in neonates and children 3, 6

Additional Testing

• Syphilis serology and HIV testing: Should be obtained in sexually active patients 1
• Blood cultures: When systemic infection suspected, particularly in neonates where sepsis occurs in 10% 3

Imaging Findings

Ultrasound - The Diagnostic Standard

Scrotal ultrasonography establishes the diagnosis in virtually all cases 3 and is the initial imaging modality of choice 4, 7.

Grayscale Findings

• Epididymal enlargement: Marked swelling more common in patients with underlying urinary tract abnormalities (53% vs 17%) 8
• Heterogeneous, hypoechoic testicular echotexture: When orchitis develops 7
• Hydrocele: Present in 66.7% of neonatal cases 3
• Scrotal wall thickening: Reflects inflammatory changes

Doppler Findings

• Increased epididymal vascularity: Hallmark finding distinguishing from testicular torsion 7
• Hyperemia: Demonstrates active inflammation 4

Complications Visible on Imaging

• Orchitis: Occurs in 43.3% of neonatal cases 3
• Scrotal abscess: Present in 20% of neonatal cases 3
• Testicular atrophy: Can develop 2-6 months after epididymitis in some pediatric patients 5

Critical Differential Diagnosis

Testicular torsion must be excluded in ALL cases, as it is a surgical emergency requiring intervention within 6-8 hours 4. Consider torsion when:

• Sudden onset of severe pain
• Adolescent patient without evidence of inflammation/infection
• Test results don't support urethritis or urinary tract infection
• Immediate specialist consultation required if diagnosis questionable 1

Associated Conditions and Risk Factors

Pediatric Population

• Genitourinary anomalies: Present in 18-28% of cases, including hypospadias, anorectal malformation, neurogenic bladder 3, 5, 6
• Recurrent epididymitis: 62% of recurrent cases have underlying genitourinary abnormalities 5
• Pre-existing infections: Upper respiratory infection, enteritis, or posthitis in 13% 5

Adult Population

• Recent urinary tract instrumentation or surgery: Risk factor for non-sexually transmitted cases 1
• Anatomical urinary tract abnormalities: More common in older men 1
• Men who have sex with men: Enteric organisms (E. coli) in insertive partners during anal intercourse 1

Common Pitfalls

1. Assuming normal urinalysis excludes epididymitis - particularly problematic in pediatric and neonatal cases where most urine tests are negative 3, 5, 6

2. Delaying imaging when torsion cannot be clinically excluded - testicular viability compromised after 6-8 hours 4

3. Missing systemic complications in neonates - including hyperbilirubinemia (16.7%), pneumonia (13.3%), and sepsis (10%) 3

4. Inadequate follow-up - testicular atrophy can develop months after apparent resolution 5