What is the recommended evaluation and management for a patient with periorbital (pre‑septal) cellulitis, including imaging, antibiotic regimen, and criteria for inpatient versus outpatient treatment?

Periorbital (Preseptal) Cellulitis: Evaluation and Management

Initial Clinical Assessment

For mild preseptal cellulitis without systemic signs, treat outpatient with high-dose oral amoxicillin-clavulanate and reassess within 24-48 hours; hospitalize immediately if the patient has systemic signs, eyelid >50% closed, extremes of age (especially infants), or any features suggesting orbital involvement (proptosis, painful/restricted eye movements, vision changes, ophthalmoplegia). 1

Critical Red Flags Requiring Immediate Hospitalization

You must examine for these specific findings that distinguish orbital from preseptal cellulitis:

• Proptosis (forward displacement of the globe—measure and compare to contralateral eye) 1, 2
• Impaired or painful extraocular movements in any direction—pain with movement indicates postseptal involvement 1, 2
• Ophthalmoplegia (paralysis of eye muscles) 1, 2
• Decreased visual acuity or vision changes 1, 2
• Diplopia (double vision) 1, 3

These findings indicate orbital cellulitis, which carries risk of permanent vision loss, cavernous sinus thrombosis, and death. 1, 2

Preseptal Cellulitis Characteristics

Infection confined to eyelids and soft tissues anterior to the orbital septum presents with:

• Periorbital swelling, hyperemia, and edema 1, 4
• No globe involvement—normal extraocular movements, no proptosis, normal vision 1
• May have fever (present in 51.5% of pediatric cases) 3

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Outpatient Management Criteria

Treat outpatient when all of the following are met:

• Eyelid less than 50% closed 1
• No proptosis or visual changes 1
• No systemic signs of infection (fever, toxicity) 1
• Reliable follow-up available within 24-48 hours 1
• Not an infant or extreme age 1, 5

Outpatient Antibiotic Regimen

First-line: High-dose oral amoxicillin-clavulanate 1

Alternatives: Cephalexin, dicloxacillin, or clindamycin 1

Mandatory reassessment within 24-48 hours to detect progression to orbital cellulitis. 1

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Inpatient Management Criteria

Hospitalize immediately for:

• Extremes of age (especially infants) 1, 5
• Systemic signs of infection (fever, toxicity) 1
• Eyelid more than 50% closed 1
• Inability to adequately examine the eye due to severe swelling 1
• Poor adherence to outpatient therapy anticipated 1
• Any clinical features suggesting orbital involvement 1, 5

Inpatient Antibiotic Regimen

Broad-spectrum IV antibiotics covering Gram-positive pathogens:

• IV amoxicillin-clavulanate 1, 5
• Cefazolin 1, 5
• Ceftriaxone 1, 5

Treatment duration: 7-14 days total, with transition to oral antibiotics once clinical improvement is demonstrated (typically after 48-72 hours of IV therapy). 5

MRSA Coverage Indications

Add MRSA-active antibiotics when:

• Penetrating trauma 1
• History of injection drug use 1
• Purulent drainage 1
• Known MRSA colonization or previous MRSA infection 1

MRSA-active IV options: Vancomycin (15 mg/kg IV every 6 hours in children), daptomycin, linezolid 1, 5

MRSA-active oral options: Clindamycin (when local MRSA resistance <10%), doxycycline (contraindicated in children <8 years), trimethoprim-sulfamethoxazole (avoid in infants <2 months) 1, 5

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Imaging Recommendations

When to Image

Obtain CT orbits with IV contrast when:

• Any clinical features suggesting orbital involvement (proptosis, restricted eye movements, vision changes) 1, 5, 2
• Failure to improve with antibiotics within 24-48 hours 1, 5
• Inability to adequately examine the eye due to severe swelling 1, 5
• Bilateral preseptal cellulitis (higher risk of cavernous sinus thrombosis) 1

CT Findings and Their Implications

CT with IV contrast is the first-line imaging modality and identifies:

• Differentiation of preseptal from postseptal (orbital) cellulitis 1, 2
• Subperiosteal abscess (most commonly along medial orbital wall from ethmoid sinusitis)—often requires surgical drainage 1, 2
• Orbital abscess 1, 2
• Underlying sinusitis (present in 77.8% of orbital cellulitis cases) 3
• Superior ophthalmic vein thrombosis 1, 2
• Cavernous sinus thrombosis 1, 2
• Bone erosion (mandates surgical intervention) 2

Fat stranding on CT signifies postseptal inflammatory change and reliably separates orbital from preseptal disease. 2

When to Add MRI

Obtain MRI head and orbits with and without contrast when:

• Clinical suspicion of intracranial extension 1, 2
• Immunocompromised status with concern for invasive fungal infection (mortality 50-80%) 1, 2
• Equivocal CT findings or CT suggesting cavernous sinus involvement 1, 2
• Multiple cranial nerve palsies (II, III, IV, V1, VI) suggesting orbital apex or cavernous sinus pathology 2

MRI provides superior soft-tissue resolution for detecting subdural empyema, meningitis, cerebritis, or brain abscess. 2

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Special Population: Infants

All infants with preseptal cellulitis require hospitalization due to their extreme age. 5

Infant-Specific Antibiotic Regimen

First-line IV therapy:

• Cefazolin 5
• Ceftriaxone 5

MRSA-active options:

• Vancomycin 15 mg/kg IV every 6 hours 5
• Clindamycin 10-13 mg/kg IV every 6-8 hours (max 40 mg/kg/day) when local MRSA resistance <10% 5

Contraindicated in infants:

• Tetracyclines (contraindicated <8 years) 5
• Trimethoprim-sulfamethoxazole (not recommended <2 months) 5

Infant Imaging Indications

Obtain contrast-enhanced CT orbits in infants with:

• Any clinical signs suggesting orbital involvement 5
• Lack of improvement after 24-48 hours of appropriate antibiotics 5
• Severe eyelid swelling precluding adequate ocular examination 5

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Critical Monitoring During Treatment

Serial Examinations Must Assess:

• Visual acuity 1, 5
• Extraocular movements in all directions 1, 5
• Degree of eyelid swelling 1, 5
• Presence of proptosis 1, 5
• Pupillary response 1, 5

Pain on extraocular movement indicates worsening orbital inflammation and should prompt repeat imaging. 2

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Catastrophic Complications to Prevent

Preseptal cellulitis can progress rapidly to:

• Orbital cellulitis with permanent vision loss from retinal artery occlusion 5, 2
• Cavernous sinus thrombosis (potentially fatal)—suspect when bilateral ophthalmoplegia develops 1, 2
• Intracranial extension: meningitis, brain abscess, subdural empyema 2
• Superior ophthalmic vein thrombosis 1, 2
• Optic nerve injury 2

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Critical Pitfalls to Avoid

• Never start corticosteroids before ophthalmology evaluation—may worsen infectious conditions. 1
• Do not delay CT imaging when proptosis, visual changes, or ophthalmoplegia are present—can lead to missed diagnosis of orbital cellulitis. 2
• Do not assume all periorbital swelling is infectious—Idiopathic Orbital Inflammatory Syndrome (IOIS) and IgG4-related disease require corticosteroids, not antibiotics. 2
• Bilateral periorbital swelling may represent cavernous sinus thrombosis—prompt imaging is essential. 1
• In immunocompromised patients, maintain low threshold for MRI to rule out invasive fungal sinusitis (mortality 50-80%). 2

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Differential Diagnosis Considerations

When imaging or clinical features are atypical, consider:

• Idiopathic Orbital Inflammatory Syndrome (IOIS): Non-infectious inflammation mimicking orbital infection; absence of fever, normal WBC, no bone erosion on imaging; requires corticosteroids. 2
• IgG4-related orbital disease: Soft-tissue enlargement without bone erosion; requires immunosuppressive therapy. 2
• Orbital abscess: Localized purulent collection requiring surgical drainage. 2

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Laboratory Markers

C-reactive protein (CRP) >120 mg/L is a useful cut-off point suggesting orbital rather than preseptal cellulitis (median CRP in orbital cellulitis: 136 mg/L vs. 18 mg/L in preseptal). 3

Blood cultures should be obtained in hospitalized patients, though yield is low (positive in only 33% of cases in one series). 4