What is epididymitis?

What is Epididymitis?

Epididymitis is an inflammatory condition of the epididymis (the coiled tube behind the testicle) that typically presents with gradual onset of unilateral testicular pain and tenderness, with palpable swelling of the epididymis usually beginning at the lower pole and progressing upward. 1, 2

Clinical Presentation

The hallmark features include:

• Unilateral testicular pain that develops gradually over hours to days, located posteriorly in the scrotum, distinguishing it from the sudden onset seen in testicular torsion 2
• Palpable epididymal swelling and tenderness that characteristically starts at the lower pole and progresses to the upper pole of the testis 1, 2
• Scrotal swelling and erythema may develop as inflammation progresses, with elevated scrotal temperature indicated by local warmth over the affected area 2
• Positive Prehn sign (pain relief when elevating the scrotum over the symphysis pubis) helps differentiate epididymitis from testicular torsion 2

Age-Dependent Etiology

The causative organisms vary dramatically by age, which determines both diagnostic approach and treatment:

Men Under 35 Years (Sexually Active)

• Sexually transmitted infections predominate: Chlamydia trachomatis (most common) and Neisseria gonorrhoeae are the primary pathogens 1, 2, 3
• These infections cause urethritis-associated epididymitis, often presenting with urethral discharge, dysuria, or urinary frequency 2
• The infection spreads via retrograde propagation through the vas deferens from urethral pathogens 3

Men Over 35 Years

• Enteric Gram-negative bacteria predominate, particularly Escherichia coli, which are transported by reflux of urine into the ejaculatory ducts secondary to bladder outlet obstruction 1, 2, 3
• These patients often have urinary tract symptoms such as weak stream, hesitancy, or urgency related to bladder outlet obstruction 2
• A urinary tract abnormality or recent urological instrumentation is often the underlying cause 2

Pathophysiology

• In most cases, the route of infection is retrograde propagation through the vas deferens from either urethral pathogens (younger men) or bladder bacteria (older men) 3
• In prepubertal children, reflux of urine into the ejaculatory ducts is considered the most common mechanism, though the etiology is largely unknown 3
• Less commonly, orchitis (testicular inflammation) can occur via hematogenous spread (particularly with viruses like mumps) or by direct extension from epididymitis, producing true epididymo-orchitis 4

Critical Differential Diagnosis

Testicular torsion must be immediately excluded in all cases of acute testicular pain, as it is a surgical emergency requiring intervention within 6-8 hours to preserve testicular viability 1, 2. Key distinguishing features include:

• Sudden onset of severe pain (torsion) versus gradual onset over hours to days (epididymitis) 2
• Negative Prehn sign (no relief with elevation) suggests torsion 2
• Emergency surgical consultation is mandatory if diagnosis is questionable 1

Diagnostic Evaluation

The diagnostic approach differs by age:

For Men <35 Years (Sexually Active)

• Urethral swab testing with nucleic acid amplification test (NAAT) for N. gonorrhoeae and C. trachomatis on intraurethral swab or first-void urine 2
• Gram-stained smear of urethral exudate showing ≥5 polymorphonuclear leukocytes per oil immersion field confirms urethritis 1
• Syphilis serology and HIV counseling/testing 1

For Men >35 Years

• Urinalysis examining first-void uncentrifuged urine for leukocytes (pyuria) 1, 2
• Urine culture and Gram stain for Gram-negative bacteria 1, 2
• Doppler ultrasound if diagnosis is uncertain or to rule out complications 2

Treatment Recommendations

Men <35 Years with Sexually Transmitted Epididymitis

Ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days is the recommended regimen 1, 2, 3

For men who practice insertive anal intercourse (enteric organism also likely): Ceftriaxone 250 mg IM single dose PLUS levofloxacin 500 mg orally once daily for 10 days 2

Men >35 Years with Enteric Organism Epididymitis

Levofloxacin 500 mg orally once daily for 10 days OR ofloxacin 300 mg orally twice daily for 10 days 1, 2, 5, 3

Adjunctive Management

• Bed rest, scrotal elevation, and analgesics until fever and local inflammation subside 1, 5
• Use of scrotal supporter to reduce edema 2

Follow-Up and Complications

• Reevaluation is mandatory if no improvement occurs within 3 days of treatment initiation 1, 2
• Persistent swelling and tenderness after completing antimicrobial therapy requires comprehensive evaluation for tumor, abscess, infarction, testicular cancer, tuberculosis, or fungal epididymitis 1
• Untreated acute epididymitis can lead to infertility and chronic scrotal pain, making recognition and therapy vital to reduce morbidity 3

Management of Sexual Partners

• Partners of patients with STI-related epididymitis should be referred for evaluation and treatment, including all partners from the 60 days preceding symptom onset 1, 5
• Patients must avoid sexual intercourse until both they and their partners complete treatment and are symptom-free 1, 5

Common Pitfalls

• Failure to exclude testicular torsion can result in testicular loss; maintain high suspicion with sudden onset or severe pain 2
• Relying solely on urinalysis in younger men misses the majority of STI-related cases, as these infections originate from urethral pathogens rather than urinary tract bacteria 2
• Inadequate partner notification and treatment perpetuates transmission and reinfection 1
• Stopping antibiotics early when symptoms improve can lead to treatment failure and chronic complications 5