Preseptal Cellulitis Workup

Updated: Mar 10, 2021
  • Author: Mounir Bashour, MD, PhD, CM, FRCSC, FACS; Chief Editor: Edsel B Ing, MD, MPH, FRCSC, PhD, MA  more...
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Workup

Approach Considerations

Blood culture results are positive in less than 10% of cases of preseptal cellulitis. Prior to the introduction of the Hib vaccine, blood cultures were positive in up to one third of patients. Blood cultures are rarely necessary in preseptal and even orbital cellulitis, unless sepsis is suspected.

White blood cell (WBC) counts tend to be elevated. One study demonstrated an average WBC count of 14,700 cells/µL in patients without bacteremia and 20,400 cells/µL in patients with bacteremia. It is generally believed that the WBC count cannot be used to differentiate preseptal cellulitis from orbital cellulitis.

Samples of conjunctival discharge, eyelid lesions, and lacrimal sac material should be sent for culture.

In patients with pain disproportionate to signs and suspected periorbital necrotizing fasciitis, the laboratory risk indicator for necrotizing fasciitis (LRINEC), particularly markedly elevated C-reactive protein levels, may be of some utility. [16]

Imaging

Findings on examination that warrant imaging studies include pain on eye movement, afferent pupillary defect, limited extraocular motions, and resistance on retropulsion.

A computed tomography (CT) scan can delineate the extent of orbital involvement but is not necessary in all patients with preseptal cellulitis. [17] Orbital ultrasonography can be a useful tool to help in diagnosing orbital inflammation, although it requires experienced observers and specialized equipment that may not be available at most institutions. Orbital ultrasound very rarely, if ever, needed.

Procedures

Consider lumbar puncture in all neonates and in patients with signs or symptoms of meningitis. Eyelid abscesses should be incised and drained if present.

Histologic findings

Biopsy shows edema and polymorphonuclear leukocytes infiltrating tissue planes.

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CT Scanning

A CT scan of the orbit is not necessary for all cases of preseptal cellulitis. For older patients who clearly have limited infection, conservative management is appropriate. When it is unclear whether deeper orbital structures are involved (eg, limited ocular motility), a CT scan is indicated. Consider imaging in all children with an advanced presentation or if a foreign body is suspected.

Findings on examination that warrant imaging studies include pain on eye movement, afferent pupillary defect, limited extraocular motions, resistance on retropulsion, and arterialization of conjunctival blood vessels.

An appropriate CT scan would include thin axial sections through the orbits and sinuses and coronal views. A CT scan of the head is also indicated for any neurologic symptoms or neurologic findings on examination.

CT scan findings in preseptal cellulitis include the following:

  • Swelling of the eyelid and adjacent preseptal soft tissues

  • Obliteration of the fat planes or details of the preseptal soft tissues

  • Absence of orbital inflammation

Staging  [18]

A CT scan can delineate the extent of orbital involvement. [17] The modified Chandler staging system describes a spectrum of disease, as follows:

  • Stage I - Preseptal cellulitis

  • Stage II - Inflammatory orbital edema

  • Stage III - Subperiosteal abscess

  • Stage IV - Orbital abscess

  • Stage V - Cavernous sinus thrombosis

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Imaging Studies

Although MRI has no ionizing radiation, orbital MRI has a much longer acquisition time than CT scanning does. MRI may be difficult to perform in young children without sedation and difficult to obtain after hours. MRI with diffusion-weighted imaging may assist in the diagnosis of orbital abscess. [19]

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