Diagnostic Approach for Acute Bacterial Rhinosinusitis
Acute bacterial rhinosinusitis (ABRS) is diagnosed clinically based on symptom patterns and cardinal features, without routine imaging or laboratory testing. 1, 2
Clinical Diagnostic Criteria
The diagnosis requires purulent nasal discharge (anterior or posterior) PLUS at least one of the following: nasal obstruction/congestion OR facial pain/pressure/fullness. 1 This combination has a sensitivity of 69% and specificity of 64% when purulent rhinorrhea and facial pain occur together. 2
Three Accepted Diagnostic Patterns
ABRS is distinguished from viral rhinosinusitis by at least ONE of these temporal patterns: 2, 3
- Persistent illness: Symptoms lasting ≥10 days without clinical improvement 1, 3
- Worsening course ("double-sickening"): Initial improvement after 5-6 days followed by new onset of fever, headache, or increased nasal discharge 1, 3
- Severe onset: High fever (≥39°C/102°F) AND purulent nasal discharge or facial pain for at least 3-4 consecutive days at illness onset 1, 2, 3
Key Clinical Features
The most diagnostically useful findings include: 1, 4, 5
- Purulent nasal discharge (essential—ABRS is unlikely without it, even when other symptoms are present) 1
- Unilateral maxillary facial/tooth pain (especially predictive when unilateral) 1, 6, 4
- Maxillary sinus tenderness 4
- Nasal obstruction/congestion 1
Important caveat: Neither nasal mucus color alone nor fever presence reliably differentiates bacterial from viral disease. 1, 3 Viral infections naturally progress from clear to purulent discharge over several days due to neutrophil influx. 3
Imaging and Special Assessments
Routine Cases: No Imaging Required
Plain radiography is neither useful nor cost-effective and should not be performed. 1 Radiographic imaging has low specificity (61%) and is not recommended for patients meeting clinical diagnostic criteria. 2
When CT Imaging IS Indicated
Computed tomography should be reserved for: 1, 2
- Suspected complications (orbital cellulitis, proptosis, vision changes, facial swelling, mental status changes) 2, 5
- Severe disease in immunocompromised patients 1
- Recurrent acute rhinosinusitis 1
- Pre-surgical evaluation 1
- Alternative diagnosis suspected 1, 2
Nasal Endoscopy
Not essential for routine diagnosis and unavailable to most primary care physicians. 1 Consider endoscopy for: 1
- Cases refractory to empirical treatment
- Unilateral disease without septal deviation
- Severe, disabling symptoms
- Treatment failure requiring culture guidance
Nasal Cultures
Not recommended for routine uncomplicated cases. 1, 2 Endoscopic cultures may be useful in: 1
- Treatment failure
- Suspected complications
- Need to identify causative organisms in specific clinical scenarios
Practical Diagnostic Algorithm
Confirm cardinal symptoms: Purulent nasal discharge PLUS nasal obstruction OR facial pain/pressure 1
Assess temporal pattern to distinguish bacterial from viral: 1, 3
- <7 days with improvement: Presumed viral
- ≥10 days without improvement: Presumed bacterial
- Worsening after initial improvement: Presumed bacterial
- Severe onset (high fever + purulent discharge for 3-4 days): Presumed bacterial
Look for high-risk features: Unilateral facial/tooth pain, fever >102°F, severe symptoms 1, 2, 5
Screen for complications (red flags): Proptosis, vision changes, facial swelling, mental status changes, orbital cellulitis 2, 5
Reserve imaging/cultures for complicated cases, treatment failures, or immunocompromised patients 1, 2
Common Pitfalls to Avoid
- Do not rely on nasal discharge color alone—viral infections also produce purulent discharge. 1, 3
- Do not order plain radiographs—they lack diagnostic utility and cost-effectiveness. 1
- Do not routinely obtain CT scans—clinical diagnosis is sufficient for uncomplicated cases. 1, 2
- Do not assume fever indicates bacterial infection—fever timing and pattern matter more than presence alone. 1, 3
- Do not diagnose ABRS before 7-10 days unless severe onset pattern is present. 1, 3