A 52-year-old man presents with a 3-day history of acute onset swelling, pain, and warmth in the left lower limb. On examination, there is pitting edema, calf tenderness, and a positive Homan's sign. D-dimer is elevated at 850 ng/mL. What is the most appropriate next step in management?

Explanation

## Clinical Scenario Analysis This patient presents with classic signs and symptoms of acute deep vein thrombosis (DVT): - Acute onset swelling and pain in lower limb - Calf tenderness and Homan's sign (though non-specific) - Elevated D-dimer ## Diagnostic Confirmation Required **Key Point:** Duplex ultrasonography (B-mode + Doppler) is the gold standard imaging modality for DVT diagnosis and should be performed urgently before initiating anticoagulation therapy. **High-Yield:** In a patient with high clinical suspicion for DVT (Wells score ≥2 points) and elevated D-dimer, imaging confirmation is mandatory. Duplex ultrasound has >95% sensitivity and specificity for proximal DVT and is non-invasive, radiation-free, and readily available. ## Why Duplex Over Other Options | Modality | Role | Timing | |----------|------|--------| | Duplex ultrasound | First-line diagnostic imaging for DVT | Urgent (same day) | | CT venography | Reserved for IVC assessment or equivocal duplex | After duplex | | MRI venography | Alternative if duplex contraindicated | Delayed | | Clinical diagnosis alone | Insufficient; 50% of clinically suspected DVT are negative | Not acceptable | **Clinical Pearl:** Bilateral imaging is recommended to assess for: - Proximal vs. distal thrombosis (affects treatment duration) - Contralateral asymptomatic DVT (present in 10–15% of cases) - IVC involvement (rare but important) ## Treatment Initiation Pathway ```mermaid flowchart TD A[Clinical suspicion of DVT]:::outcome --> B[Perform duplex ultrasound]:::action B --> C{DVT confirmed?}:::decision C -->|Yes| D[Start anticoagulation]:::action C -->|No| E[Reassess clinical status]:::action D --> F[Heparin/DOAC/LMWH]:::action F --> G[Warfarin or DOAC long-term]:::action ``` **Key Point:** Anticoagulation should NOT be initiated before imaging confirmation in stable patients, as false-positive clinical diagnosis occurs in ~50% of cases and exposes patients to unnecessary bleeding risk. [cite:Sabiston Textbook of Surgery Ch 64]