Orbital Floor Fractures (Blowout) Workup

Updated: Feb 08, 2022
  • Author: Adam J Cohen, MD; Chief Editor: Deepak Narayan, MD, FRCS  more...
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Laboratory Studies

If alcohol or illicit drug use is suspected, obtain and document serum levels.

As with most surgical patients, appropriate preoperative laboratory tests (eg, complete blood count, metabolic panels, activated partial thromboplastin time) and an international normalized ratio level are necessary. Obtain a pregnancy test when warranted.


Imaging Studies

Radiographs can be used for soft tissue but are limited by the lack of ability to detect differences in tissue density of less than 10%, making evaluation of soft tissue difficult at best. Anteroposterior views of the orbit usually are obtained with varying angulation of the x-ray beam vector.

The most common views are the Caldwell and Waters projections. The Caldwell projection allows for visualization of the orbital floor and orbital zygomatic process above the dense petrous pyramids. A more extended view of the orbit is afforded by the Waters projection. This angle of x-ray trajectory places the petrous pyramids below the maxillary sinus, allowing evaluation of the orbital floor, prolapsed orbital contents, and air-fluid levels in the maxillary sinus. Ng et al found a poor correlation between soft tissue opacities below the inferior orbital rim and inferior rectus muscle entrapment with a Waters view.

Lateral views often are confusing because of overlapping anatomic structures and offer little in the assessment of floor fractures.

Computed tomography (CT) scanning has supplanted radiographs in evaluation of midfacial trauma (see images below).

Coronal CT scan showing orbital floor fracture pos Coronal CT scan showing orbital floor fracture posterior to the globe. A fracture of the lateral maxillary sinus wall also is present.
Coronal CT scan showing posterior extension of flo Coronal CT scan showing posterior extension of floor fracture.

A gray-scale image is created based on various soft tissue linear coefficients that are assigned a particular shade of gray. Direct axial, coronal, or sagittal images can be obtained with proper positioning of the patient. CT scanning without contrast provides views of high-density bone. Obtain both axial and direct coronal 1.5- to 2.0-mm cuts to properly evaluate the orbit and the floor. If the patient cannot be manipulated into proper position for direct coronal images, coronal views also may be obtained indirectly by reformatting thin axial windows. However, direct coronal images are preferable. Coronal orbital views provide bony and soft tissue windows, allowing for excellent detail of orbital floor fractures, adjacent sinuses, and soft tissue entrapment (see image below).

Coronal CT scan (soft tissue window) showing right Coronal CT scan (soft tissue window) showing right orbital floor fracture, vertical elongation of right orbit, reduction in size of right maxillary sinus, and soft tissue swelling of the right maxillary sinus mucosa.

A study by Huang et al indicated that in patients with head trauma, lack of maxillary hemosinus on conventional head CT scanning predicts the absence of orbital floor fracture, the negative predictive value being 99.7%. Maxillary hemosinus with high-attenuation opacity mixed with mottled gas was found to be the only type of maxillary hemosinus to independently predict orbital floor fracture. [15]

A study by Bruneau et al indicated that CT scan–based evaluation for pure orbital floor blowout fractures can be used to predict ophthalmologic outcomes, with, for example, the area ratio of the fractured orbital floor and the maximum height of periorbital tissue herniation being predictive for enophthalmos and diplopia, respectively. [16]

A study by Goggin et al indicated that the defect size of orbital floor fractures may be overestimated if simple, rapid geometric formulas are used to calculate the value from CT scans. Such formulas are highly sensitive but lack specificity, according to the investigators, who recommended instead that more time-consuming analysis, employing coronal CT scans and taking into account the thickness and number of image slices, be used to derive the defect size. [17]

Magnetic resonance imaging (MRI) uses a magnetic field and the activity of hydrogen atoms within this field to produce detailed images of the orbit. MRI enables multiplanar imaging and is excellent for evaluating soft tissue masses and optic nerve pathology.

Even though MRI provides exquisite detail of the orbital region, CT scanning remains the imaging modality of choice for evaluation of orbital trauma. Of note, intraocular ferromagnetic foreign bodies can add additional insult to the eye and surrounding structures secondary to the magnetic field of the MRI scan.


Other Tests

An ECG also may be indicated.


Diagnostic Procedures

If the CT scan is equivocal when evaluating a patient with presumed entrapment, forced ductions can be performed. Directly assessing the ability or inability to further supraduct or infraduct the eye can yield important clinical confirmation of an entrapped muscle or tissue or of a paretic muscle.