Imaging for Deviated Nasal Septum
Imaging is generally NOT recommended for diagnosing a deviated nasal septum—clinical examination with anterior rhinoscopy and nasal endoscopy is the reference standard and should be used instead. 1
Primary Diagnostic Approach
Nasal endoscopy (flexible or rigid) is the most accurate first-line confirmatory test for diagnosing deviated nasal septum, performed after application of topical decongestant and anesthetic. 1 This allows direct visualization of:
- The nasal cavity and septum
- Turbinates and meatus areas
- Uncinate process and hiatus semilunaris
- Maxillary ostia and ethmoidal bulla
- Nasopharynx 1
When CT Imaging Should NOT Be Used
The American College of Radiology explicitly states that CT scanning should NOT be performed solely for evaluation of septal deviation. 1 Key limitations include:
- Limited correlation with physical examination findings 1
- May underestimate the degree of nasal obstruction at the internal nasal valve area 1
- The nasal septum is off-center in approximately 80% of the general population and appears deviated by CT in up to 56%, but only 26% have clinically significant deviation causing symptoms 2
Critical Pitfall to Avoid
Relying solely on CT imaging without clinical examination leads to underestimation of the functional impact of septal deviation and may result in treating anatomic findings that are not clinically significant. 1
When CT Imaging IS Appropriate
CT of the paranasal sinuses should be obtained when:
- Evaluating associated symptoms of chronic rhinosinusitis 1
- Planning surgical intervention when additional sinonasal pathology is suspected 3
- Complex nasal injuries with associated facial fractures are present 2
Surgical Planning Context
When septoplasty is already planned based on clinical examination, preoperative CT can identify:
- Concha bullosa requiring lateral resection 4
- Inferior turbinate hypertrophy 4
- Chronic sinusitis requiring endoscopic sinus surgery 4
- Retention cysts, paradoxical middle turbinate, or other pathology 4
Research shows that 27.5% of patients with symptomatic deviated septum required additional surgical procedures after CT revealed concomitant pathology. 3
Systematic Clinical Assessment
When examining clinically, divide the nose into horizontal thirds (upper, middle, lower) and assess each third in relation to the midline. 1 This approach:
- Facilitates systematic analysis 1
- Guides potential surgical treatment planning 1
- Helps distinguish between true deviation and nasal asymmetry 1
Clinical Significance by Location
Anterior septal deviation is more clinically significant than posterior deviation because it affects the nasal valve area, which is responsible for more than 2/3 of nasal airflow resistance. 2, 1 A small anterior deviation causes more symptoms than a larger posterior deviation. 2
Alternative Imaging Modalities
Ultrasound has shown high accuracy (90-100% sensitivity, 98-100% specificity) for detecting isolated nasal bone fractures in trauma settings, but is not typically the first-line imaging test for evaluating deviated septum. 2, 1
Plain radiographs have limited diagnostic value with accuracy ranging only 53-82% for nasal bone fractures and do not considerably alter diagnosis or management of nasal deviations. 2