A 58-year-old man with a 3-day history of acute onset dyspnea and pleuritic chest pain presents to the emergency department. His D-dimer is elevated at 2.5 µg/mL. Chest X-ray shows a small right pleural effusion but no consolidation or pneumothorax. Arterial blood gas reveals mild hypoxemia (PaO₂ 72 mmHg on room air). Clinical suspicion for pulmonary embolism is high. What is the most appropriate next step in management?

Question

Accepted Answer

C. Obtain CT pulmonary angiography (CTPA) immediately. ## Clinical Context
This patient has a high pretest probability of PE based on acute dyspnea, pleuritic chest pain, elevated D-dimer, and hypoxemia. The chest X-ray is relatively clear, making it suitable for CTPA imaging.

## Why CTPA is the Next Step

**Key Point:** CT pulmonary angiography (CTPA) is the gold standard imaging modality for diagnosis of PE in hemodynamically stable patients with high clinical suspicion and interpretable chest X-rays.

**High-Yield:** CTPA has:
- Sensitivity: 83–100% (depending on PE size and technique)
- Specificity: >95%
- Fast acquisition time (10–15 seconds)
- Allows assessment of right heart strain and alternative diagnoses

## Management Algorithm

```mermaid
flowchart TD
  A[High clinical suspicion PE + elevated D-dimer]:::outcome --> B{Hemodynamically stable?}:::decision
  B -->|Yes| C{CXR interpretable?}:::decision
  B -->|No| D[Thrombolysis or embolectomy]:::urgent
  C -->|Yes| E[CTPA immediately]:::action
  C -->|No| F[Bedside echo or V/Q scan]:::action
  E --> G{PE confirmed?}:::decision
  G -->|Yes| H[Anticoagulation]:::action
  G -->|No| I[Investigate alternative diagnosis]:::action
```

**Clinical Pearl:** Anticoagulation should NOT be delayed awaiting imaging in high-risk patients, but CTPA is performed urgently (not after anticoagulation is started). In this case, the patient is hemodynamically stable, so CTPA is the diagnostic priority.

**Tip:** Remember the "rule of 90s" — CTPA should be performed within 90 minutes of presentation in suspected PE to guide definitive therapy.

[cite:Harrison 21e Ch 297]

![Pulmonary Embolism — CT Imaging diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/4108.webp)

Answer

A. Start empirical thrombolysis and arrange CTPA within 24 hours

Answer

B. Administer therapeutic anticoagulation with unfractionated heparin while awaiting CT pulmonary angiography

Answer

D. Perform V/Q scan to exclude PE before commencing anticoagulation

Explanation

Clinical Context

Why CTPA is the Next Step

Management Algorithm

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