Head and Neck Imagingair-fluid level, head and neck
Most air-fluid levels are visualized in the
paranasal sinuses (most frequently in the
maxillary sinus
) and result from acute bacterial
sinusitis
. An air-fluid level is used to diagnose radiographically an acute bacterial sinusitis (
Fig. 1), but this sign is only present in half of cases; conversely, a
paranasal air-fluid level is also seen in a number of other conditions (Table 1). A sinusal polyp (see
sinonasal cavities, polyposis
) or
retention cyst
may appear flat and mimic an air-fluid level (
Fig. 2) (see also
mucous retention cyst
).
Air-fluid levels may also be seen in the
middle ear
and mastoid cells, due to serous
otitis media
,
cerebrospinal fluid leak
or post-traumatic bleeding (see
haemotympanon
).
Air-fluid level, Table 1. Causes of air-fluid level in
paranasal sinuses.
| Acute bacterial sinusitis |
| Sinus lavage for treatment of bacterial sinusitis |
| Post-traumatic haemosinus |
| Nasal tubation (e.g. nasogastric tube) |
| Barotrauma |
| Chemically induced sinusitis |
| Cerebrospinal fluid leak (HN) |
| Allergy (rare) |
| Nasal obstrution by mass lesion (rare) |
RH
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Already registered? Enter your e-mail in the window below.Re-registerFig. 02a
Coronal CT-image shows extensive inflammatory changes in the ethmoidal cells, and an air-fluid level in the right maxillary sinus. The largest part of the soft tissue density in the left maxillary sinus is formed by a polyp or retention cyst, displaying a slightly upwards convex border; only the soft tissue thickening against the walls corresponds to inflammation in this sinus.
 | |  | |
air-fluid level, head and neck, Fig. 01a | | air-fluid level, head and neck, Fig. 02a | |