A 32-year-old woman presents with a 3-week history of nasal obstruction, facial pain, and purulent nasal discharge. Clinical examination reveals mucosal edema and pus in the middle meatus. She has failed medical management with antibiotics and nasal decongestants for 2 weeks. Which investigation is most appropriate to confirm the diagnosis and guide further management?

Explanation

## Investigation of Choice for Acute Sinusitis Diagnosis ### Clinical Context This patient has clinical and endoscopic evidence of acute sinusitis that has not responded to medical therapy. The next step is imaging to confirm the diagnosis, identify the affected sinuses, assess for complications, and determine candidacy for endoscopic sinus surgery (ESS). ### Why High-Resolution CT is the Gold Standard **High-Yield:** CT is the imaging modality of choice for acute sinusitis when: - Diagnosis is uncertain despite clinical findings - Medical management has failed - Surgical intervention is being considered - Complications (orbital, intracranial) are suspected **Key Point:** HRCT provides: - Precise anatomical detail of all paranasal sinuses - Identification of ostiomeatal complex obstruction - Detection of bony landmarks critical for ESS planning - Assessment of bone erosion or intracranial extension - Superior sensitivity (95–100%) for sinusitis compared to plain films ### Comparison of Imaging Modalities | Investigation | Sensitivity | Specificity | When Used | Limitations | |---|---|---|---|---| | **Plain radiograph** | 60–70% | Moderate | Screening only; rarely used now | Poor soft tissue detail; misses 30–40% of disease | | **HRCT** | 95–100% | High | Diagnosis, pre-op planning, complications | Radiation exposure; cost | | **MRI** | High | High | Fungal sinusitis, tumor, intracranial extension | Expensive; long acquisition; not for acute ESS planning | | **Nasal endoscopy** | Variable | Variable | Clinical assessment; therapeutic drainage | Does not assess posterior ethmoids or sphenoid fully | **Clinical Pearl:** Endoscopy is a clinical tool, not a diagnostic imaging investigation. While it confirms middle meatal pus, it does not delineate the extent of sinus involvement or guide surgical anatomy. ### Mnemonic for Imaging Choice in Sinusitis **CHOP** — CT for Complicated/Chronic, Hospitalized, Operative planning ### Algorithm for Investigation ```mermaid flowchart TD A[Suspected acute sinusitis]:::outcome --> B{Clinical diagnosis clear?}:::decision B -->|Yes, mild| C[Empiric antibiotics + decongestants]:::action B -->|No, or failed medical Rx| D[Nasal endoscopy]:::action D --> E{Pus in meatus?}:::decision E -->|Yes| F[HRCT sinuses]:::action E -->|No| G[Consider alternative diagnosis]:::outcome F --> H{Complications or surgery planned?}:::decision H -->|Yes| I[ESS with CT-guided navigation]:::action H -->|No| J[Medical management or repeat imaging]:::action ``` [cite:Scott-Brown's Otolaryngology 8e Ch 5.2]