What is the recommended workup and treatment for a patient presenting with periorbital cellulitis in the emergency department?

Periorbital Cellulitis Workup in the Emergency Department

For patients presenting with periorbital cellulitis in the ED, obtain CT orbits with IV contrast as the initial imaging modality to differentiate preseptal from postseptal cellulitis and identify complications requiring surgical intervention, while blood cultures are generally unnecessary for typical cases. 1

Initial Clinical Assessment

Distinguish preseptal (periorbital) from postseptal (orbital) cellulitis immediately, as this determines the entire management pathway. 1

Key Clinical Features to Assess

• Proptosis, limitation of extraocular movements, or pain with eye movement indicate postseptal involvement requiring immediate imaging and hospitalization. 1, 2
• Preseptal cellulitis is confined to eyelids and soft tissues anterior to the orbital septum, while postseptal extends behind the septum into the orbit. 1
• Check visual acuity in all patients—any impairment suggests orbital involvement with potential optic nerve compromise. 1
• Measure degree of eyelid closure—less than 50% closure suggests milder disease potentially manageable as outpatient. 3

High-Risk Features Requiring Aggressive Workup

• Age >3 years increases abscess risk. 2
• Absence of infectious conjunctivitis increases abscess risk. 2
• Gross periorbital edema increases abscess risk. 2
• Previous antibiotic therapy increases abscess risk. 2
• Peripheral blood neutrophil count >10,000/μL strongly predicts intraorbital abscess. 2

Imaging Strategy

CT Orbits with IV Contrast - First-Line Imaging

CT orbits with IV contrast is the most useful initial imaging for suspected orbital infection in the ED. 1

• Differentiates preseptal from postseptal cellulitis and identifies subperiosteal or intra-orbital abscesses. 1
• Detects underlying sinusitis (present in 79% of orbital cellulitis cases). 4
• Identifies complications including superior ophthalmic vein thrombosis, cavernous sinus thrombosis, or subdural empyema. 1
• Precontrast imaging is typically unnecessary as it adds no significant diagnostic information. 1

When to Add MRI

MRI orbits and brain with and without IV contrast should be obtained if intracranial complications are suspected based on altered mental status, severe headache, or CT findings suggesting intracranial extension. 1

• MRI provides superior soft-tissue resolution for assessing cavernous sinus involvement. 1
• Consider MRI in immunocompromised patients where invasive fungal infection is a concern, as these infections carry high morbidity. 1

Laboratory Workup

Blood Cultures - Generally Not Indicated

Blood cultures should NOT be obtained routinely in typical periorbital cellulitis cases. 1, 5

• Blood cultures are positive in only 0-1% of preseptal cellulitis cases. 6
• Reserve blood cultures for patients with:
  • Malignancy or severe immunodeficiency 5
  • Severe systemic features (SIRS criteria, hypotension, altered mental status) 5
  • Suspected intravascular prosthesis seeding 1

Other Laboratory Tests

• Complete blood count with differential—neutrophil count >10,000/μL predicts abscess in 50% of cases without obvious clinical signs. 2
• Wound or abscess cultures if purulent drainage present—Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus milleri are predominant organisms. 4, 7

Treatment Initiation in the ED

Antibiotic Selection Algorithm

For uncomplicated preseptal cellulitis without MRSA risk factors, initiate high-dose amoxicillin-clavulanate (Augmentin 875/125 mg twice daily in adults) as first-line therapy. 5, 3

• This provides comprehensive coverage for streptococci, staphylococci, and anaerobes. 3
• Treatment duration is 5 days if clinical improvement occurs, extending only if symptoms persist. 5

When to Add MRSA Coverage

MRSA coverage is generally unnecessary for typical periorbital cellulitis (beta-lactam therapy succeeds in 96% of cases). 3

Add MRSA coverage with vancomycin (IV) or clindamycin (oral) only when specific risk factors present: 5, 3

• Penetrating trauma to the periorbital area
• Purulent drainage or exudate
• Evidence of MRSA infection elsewhere
• History of injection drug use
• Failure of initial beta-lactam therapy after 24-48 hours

Severe Cases Requiring IV Therapy

For postseptal (orbital) cellulitis or severe preseptal cellulitis with systemic toxicity, initiate IV cefazolin 1-2 g every 8 hours or nafcillin/oxacillin 2 g every 6 hours. 5

• If MRSA suspected, use vancomycin 15-20 mg/kg IV every 8-12 hours. 5
• For suspected necrotizing infection or severe systemic toxicity, use vancomycin PLUS piperacillin-tazobactam 3.375-4.5 g IV every 6 hours. 5

Disposition Decision Algorithm

Admit to Hospital If:

• Any signs of postseptal involvement (proptosis, ophthalmoplegia, pain with eye movement, visual impairment) 1, 5
• Systemic inflammatory response syndrome (SIRS) (fever >38°C, tachycardia, tachypnea) 5
• Altered mental status or hemodynamic instability 5
• Age <1 year 3
• Immunocompromised state 5
• CT evidence of subperiosteal or orbital abscess 1

Discharge Home If:

• Preseptal cellulitis only (no orbital signs) 3
• Eyelid closure <50% 3
• No systemic toxicity 3
• Reliable patient/family for daily follow-up 3
• Mandatory daily follow-up until definite improvement documented 3

Critical Pitfalls to Avoid

• Do not assume bilateral periorbital swelling is always cellulitis—consider venous congestion from cavernous sinus thrombosis, which requires immediate vascular imaging. 1
• Do not delay CT imaging in children with high-risk features—50% of patients with abscess lack obvious proptosis or ophthalmoplegia. 2
• Do not reflexively add MRSA coverage for typical non-purulent periorbital cellulitis without specific risk factors—this represents overtreatment. 5, 3
• Do not extend antibiotics beyond 5 days if clinical improvement has occurred—residual erythema alone does not justify prolonged therapy. 5
• Do not obtain blood cultures routinely—they are positive in <1% of preseptal cases and do not change management. 1, 6

Adjunctive Measures

• Elevate the head of bed to promote gravity drainage of periorbital edema. 5
• Treat underlying sinusitis if present (79% of orbital cellulitis cases have associated sinusitis). 4
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adults to reduce inflammation, though evidence is limited. 5