What is the appropriate work‑up for a child presenting with unilateral periorbital discoloration or swelling?

Workup of Unilateral Periorbital Discoloration or Swelling in Children

The immediate priority is to distinguish preseptal cellulitis from orbital cellulitis through targeted clinical examination and selective CT imaging, as orbital cellulitis represents a vision- and life-threatening emergency requiring urgent hospitalization and IV antibiotics. 1, 2

Critical Initial Clinical Assessment

Examine specifically for these red-flag features that indicate postseptal (orbital) involvement:

• Proptosis (measure and compare to contralateral eye) 1, 3
• Painful or restricted extraocular movements (test in all directions—pain with movement indicates orbital involvement) 1, 3, 2
• Ophthalmoplegia (suggests orbital cellulitis or cavernous sinus thrombosis) 1
• Visual acuity changes or relative afferent pupillary defect (indicates optic nerve compromise) 2
• Fever and systemic toxicity (elevated temperature, elevated CRP and white blood cell count suggest infectious etiology) 4

If ANY of these orbital signs are present, obtain CT orbits with IV contrast immediately. 1, 3

Age-Specific Considerations in Neonates and Young Infants

In neonates and infants <3 months with periorbital swelling and discharge:

• Purulent conjunctivitis is an emergency until gonococcal infection is ruled out (can cause corneal perforation within 24-48 hours, septicemia, meningitis, and death) 5
• Perform fluorescein staining immediately to detect corneal involvement, which mandates urgent ophthalmology referral 5
• Look for eyelid vesicles (pathognomonic for HSV conjunctivitis requiring immediate ophthalmology referral) 5
• Consider dacryocystocele with acute dacryocystitis if there is bluish swelling over the nasolacrimal sac with erythema and warmth (requires urgent ophthalmology referral due to high risk of orbital cellulitis, meningitis, and sepsis) 6

Imaging Decision Algorithm

Obtain CT orbits with IV contrast immediately if:

• Proptosis, ophthalmoplegia, or painful extraocular movements are present 1, 3
• Visual changes or abnormal pupillary response detected 1, 2
• Fever with periorbital edema in a child >3 years old 3
• Peripheral blood neutrophil count >10,000/μL with gross periorbital edema 3
• Absence of infectious conjunctivitis with significant periorbital swelling 3

CT accurately identifies subperiosteal abscess, orbital abscess, bone erosion, and intracranial complications with 97% accuracy. 1

Risk Stratification for Abscess

Even without classic orbital signs, 50% of children with intraorbital abscess do not present with proptosis or ophthalmoplegia. 3 Additional risk factors include:

• Age >3 years 3
• Previous antibiotic therapy (suggesting treatment failure) 3
• Neutrophil count >10,000/μL 3
• Gross periorbital edema without conjunctivitis 3

Differential Diagnosis Beyond Infection

Consider non-infectious causes in 61% of cases presenting with acute orbital swelling: 4

• Idiopathic Orbital Inflammatory Syndrome (IOIS): mimics orbital infection but requires corticosteroids rather than antibiotics (diagnosis of exclusion) 1
• IgG4-related orbital disease: accounts for significant percentage of previously "idiopathic" inflammation 1
• Orbital tumors: present in rare cases as acute swelling 4
• Atheroma, insect stings, dental abscess: localized causes without systemic signs 4
• Allergic or traumatic causes: typically without fever or elevated inflammatory markers 7

Immediate Management Based on Findings

For confirmed orbital cellulitis (postseptal involvement):

• Immediate hospitalization with IV broad-spectrum antibiotics covering Staphylococcus aureus, Streptococcus species, and anaerobes 1
• Urgent ophthalmology and otolaryngology consultation for potential surgical drainage 1
• Indications for functional endoscopic sinus surgery (FESS): failure to improve within 24 hours, subperiosteal abscess on CT, or vision loss 4

For preseptal cellulitis (no orbital signs):

• Oral antibiotics may be sufficient in most cases 1
• Close monitoring for progression to orbital involvement 2

Critical Pitfalls to Avoid

• Delaying CT when orbital signs are present can lead to missed diagnosis of abscess, cavernous sinus thrombosis, meningitis, or brain abscess 1
• Assuming all periorbital swelling is infectious and missing inflammatory conditions like IOIS that require corticosteroids 1
• Treating presumed preseptal cellulitis without reassessment when symptoms worsen or fail to improve within 24-48 hours 2
• Missing gonococcal conjunctivitis in neonates by not treating purulent discharge as an emergency 5
• Failing to examine for nasal endoscopy findings: pus in the middle meatus confirms sinusitis as the source 4