A 32-year-old woman presents with a 3-week history of nasal congestion, purulent nasal discharge, and facial pain over the maxillary region. She has already completed a 10-day course of amoxicillin-clavulanate without improvement. On examination, she has tenderness over the maxillary sinuses and purulent discharge in the middle meatus. Plain sinus X-ray shows opacification of the maxillary sinuses bilaterally. What is the most appropriate next step in management?

Explanation

## Clinical Assessment This patient has **acute bacterial rhinosinusitis** (ABRS) that has failed first-line antibiotic therapy after 10 days. The clinical presentation includes: - Purulent nasal discharge - Facial pain and maxillary tenderness - Imaging confirmation (opacification on X-ray) - No response to appropriate antibiotics ## Why CT Scan Is the Next Step **Key Point:** When acute sinusitis fails to respond to appropriate antibiotics within 7–10 days, imaging escalation is indicated to: 1. Confirm the diagnosis and extent of disease 2. Exclude complications (orbital cellulitis, intracranial extension) 3. Identify anatomical variants or obstructive pathology 4. Guide further management (medical vs. surgical) CT is superior to plain X-ray because it provides: - Detailed anatomical definition of sinuses and ostiomeatal complex - Detection of bone erosion or complications - Assessment of sinus drainage pathways ## Management Algorithm for Acute Sinusitis ```mermaid flowchart TD A[Acute rhinosinusitis]:::outcome --> B{Clinical diagnosis + risk factors?}:::decision B -->|Mild, no complications| C[First-line: Amoxicillin-clavulanate + saline irrigation]:::action B -->|Severe or immunocompromised| D[Broad-spectrum antibiotic]:::action C --> E{Response in 7-10 days?}:::decision D --> E E -->|Yes| F[Continue antibiotics + supportive care]:::action E -->|No| G[CT PNS to assess extent]:::action G --> H{Complications or severe disease?}:::decision H -->|Yes| I[FESS or hospitalization]:::urgent H -->|No| J[Change antibiotic + topical steroids]:::action ``` **High-Yield:** The **7–10 day rule** is critical: if ABRS does not improve with appropriate antibiotics by day 7–10, imaging (CT) is mandatory before escalating to surgery. **Clinical Pearl:** Plain X-ray has limited sensitivity (~60%) for sinusitis; CT is the gold standard for diagnosis and surgical planning in complicated or recurrent cases. ## Why Other Options Are Incorrect - **Continuing antibiotics without imaging:** Risks missing complications and delays diagnosis of anatomical obstruction. - **Immediate FESS:** Premature without imaging confirmation; FESS is reserved for recurrent/chronic sinusitis or complications, not first-line treatment failure. - **Intranasal steroids alone:** Insufficient for bacterial sinusitis; may delay necessary intervention. [cite:Harrison 21e Ch 146]