What is the appropriate workup and treatment for a patient with scrotal cellulitis in the emergency department, considering their past medical history, demographics, and potential complications?

Scrotal Cellulitis Workup in the Emergency Department

For scrotal cellulitis in the ED, immediately rule out testicular torsion and Fournier's gangrene with urgent ultrasound and clinical assessment, then initiate broad-spectrum IV antibiotics covering streptococci, MRSA, and anaerobes while obtaining blood cultures and surgical consultation.

Critical Initial Assessment: Rule Out Life-Threatening Conditions

Testicular Torsion Exclusion

• Emergency ultrasound with Doppler is mandatory to assess testicular blood flow and rule out torsion, which requires immediate surgical intervention 1.
• Testicular torsion is more frequent among adolescents and occurs more commonly in patients without evidence of inflammation or infection 1.
• If the diagnosis is questionable or onset of pain is sudden and severe, obtain immediate surgical consultation because testicular viability may be compromised 1.

Fournier's Gangrene Recognition

• Assess for warning signs of necrotizing fasciitis: severe pain out of proportion to examination, skin anesthesia, rapid progression, "wooden-hard" subcutaneous tissues, gas in tissue, systemic toxicity, or bullous changes 2, 3.
• Fournier's gangrene is a polymicrobial necrotizing fasciitis affecting the genital region that requires emergent surgical debridement and can be initially misdiagnosed as simple cellulitis 4, 3.
• If necrotizing infection is suspected, obtain emergent surgical consultation for diagnostic and therapeutic debridement 2.

Diagnostic Workup

Laboratory Studies

• Obtain blood cultures in all patients with scrotal cellulitis, particularly those with fever, systemic signs, or immunocompromise 2.
• Consider urethral swab for N. gonorrhoeae and C. trachomatis testing if sexually transmitted epididymitis is suspected 1.
• Gram stain and culture of urethral exudate or intraurethral swab specimen for N. gonorrhoeae (≥5 polymorphonuclear leukocytes per oil immersion field indicates urethritis) 1.
• Culture and Gram stain of uncentrifuged urine for Gram-negative bacteria 1.
• Syphilis serology and HIV counseling/testing should be obtained 1.

Imaging

• Scrotal ultrasound with Doppler is the primary imaging modality to assess testicular perfusion, rule out abscess formation, and evaluate for epididymitis 1.
• Consider CT imaging if Fournier's gangrene is suspected and clinical findings are equivocal 3.

Physical Examination Priorities

• Assess for purulent drainage or fluctuance, as any abscess requires incision and drainage as primary treatment 2.
• Examine for unilateral testicular pain and tenderness with palpable epididymal swelling, suggesting epididymitis rather than pure cellulitis 1.
• Document extent of erythema, warmth, and induration to track progression 2.
• Assess for systemic toxicity: fever, hypotension, tachycardia, altered mental status, or SIRS criteria 2.

Antibiotic Selection Algorithm

Severe Scrotal Cellulitis or Suspected Fournier's Gangrene

Initiate broad-spectrum combination therapy immediately (within 1 hour of recognition) 2:

• Vancomycin 15-20 mg/kg IV every 8-12 hours (for MRSA and streptococcal coverage) 2
• PLUS Piperacillin-tazobactam 3.375-4.5 g IV every 6 hours (for polymicrobial and anaerobic coverage) 2
• Alternative combinations include vancomycin plus a carbapenem (meropenem 1 g IV every 8 hours) or vancomycin plus ceftriaxone 2 g IV daily and metronidazole 500 mg IV every 8 hours 2.

The rationale: Scrotal cellulitis can rapidly progress to Fournier's gangrene, which is polymicrobial involving streptococci, staphylococci, and anaerobes 5, 4. Beta-hemolytic streptococci are the most common cause of scrotal cellulitis without a discernible portal of entry 5.

Uncomplicated Scrotal Cellulitis Without Systemic Toxicity

If Fournier's gangrene is definitively ruled out and the patient is stable:

• Vancomycin 15-20 mg/kg IV every 8-12 hours as first-line monotherapy (A-I evidence) 2
• Alternative options include linezolid 600 mg IV twice daily, daptomycin 4 mg/kg IV once daily, or clindamycin 600 mg IV every 8 hours if local MRSA resistance is <10% 2.

If Sexually Transmitted Epididymitis is Suspected

• Ceftriaxone 250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 10 days 1.
• Alternative: Ofloxacin 300 mg orally twice daily for 10 days (contraindicated in patients ≤17 years) 1.

Treatment Duration and Monitoring

• For severe cellulitis with systemic toxicity or Fournier's gangrene: 7-14 days total therapy, guided by clinical response 2.
• For uncomplicated cellulitis: 5 days if clinical improvement occurs, extending only if symptoms have not improved 2.
• Mandatory reassessment within 24-48 hours to verify clinical response 2.
• Failure to improve within 3 days requires re-evaluation of diagnosis and therapy, with consideration for hospitalization 1.

Adjunctive Measures

• Bed rest and scrotal elevation until fever and local inflammation subside 1.
• If abscess or necrotic tissue is identified, surgical debridement is mandatory and takes priority over antibiotics alone 5, 4.
• For Fournier's gangrene, radical debridement of necrotic tissue plus a wide margin of adjacent inflamed skin is required 5.

Common Pitfalls to Avoid

• Do not delay surgical consultation if any signs of necrotizing infection are present—these infections progress rapidly and require debridement 2, 3.
• Do not use beta-lactam monotherapy for scrotal cellulitis in the ED setting, as the risk of polymicrobial infection including anaerobes is substantial 5, 4.
• Do not continue ineffective antibiotics beyond 48 hours—progression despite appropriate therapy indicates resistant organisms or deeper infection 2.
• Fournier's gangrene is commonly misdiagnosed as simple cellulitis in early stages, leading to delayed treatment and poor outcomes 3.

Disposition Criteria

Mandatory Hospitalization Indications

• Signs of systemic toxicity (SIRS, fever, hypotension, altered mental status) 2
• Suspected or confirmed Fournier's gangrene 4, 3
• Severe immunocompromise or neutropenia 2
• Rapid progression despite initial therapy 2
• Inability to tolerate oral medications 2