A 58-year-old man presents to the emergency department with acute onset of right calf pain, swelling, and warmth for 24 hours. He has been immobilized for 2 weeks following a femur fracture. On examination, calf circumference is 4 cm greater on the right than the left, and Homan's sign is positive. D-dimer is elevated at 2.5 μg/mL (normal <0.5). Compression ultrasound of the right lower limb shows an echogenic thrombus in the popliteal vein. What is the most appropriate immediate management?

Explanation

## Acute Deep Venous Thrombosis (DVT): Diagnosis and Anticoagulation **Key Point:** Confirmed DVT requires immediate anticoagulation to prevent pulmonary embolism and post-thrombotic syndrome. Unfractionated heparin (UFH) is the gold standard for acute DVT, especially when thrombolysis or IVC filter placement may be needed. ### Clinical Diagnosis This patient has: - **Risk factors:** Immobilization (femur fracture × 2 weeks) — major risk factor - **Classic signs:** Calf pain, swelling, warmth, positive Homan's sign - **Confirmatory imaging:** Compression ultrasound showing popliteal vein thrombus - **Laboratory:** Elevated D-dimer (supports but does not diagnose DVT) **High-Yield:** Proximal DVT (popliteal, femoral, iliac) carries **high risk of PE** and requires aggressive anticoagulation. Distal DVT (calf veins) has lower PE risk but still requires treatment. ### Anticoagulation Strategy for Acute DVT ```mermaid flowchart TD A[Confirmed DVT on ultrasound]:::outcome --> B{Contraindication to anticoagulation?}:::decision B -->|No| C[Start UFH or LMWH]:::action B -->|Yes| D[Consider IVC filter]:::action C --> E{Thrombolysis candidate?}:::decision E -->|Proximal DVT + limb-threatening| F[UFH preferred for thrombolysis]:::action E -->|Standard proximal DVT| G[LMWH or UFH + transition to DOAC/warfarin]:::action E -->|Distal DVT| H[LMWH or UFH, then DOAC/warfarin]:::action ``` ### Why Unfractionated Heparin (UFH)? | Feature | UFH | LMWH | DOAC | |---------|-----|------|------| | **Onset** | Immediate (IV) | 2–4 hours (SC) | 2–4 hours (oral) | | **Reversibility** | Protamine reversal | Partial reversal | No reversal | | **Thrombolysis** | Preferred (easy titration) | Acceptable | Avoid | | **Renal clearance** | Hepatic | Renal | Renal/hepatic | | **Monitoring** | aPTT required | Not required | Not required | **Clinical Pearl:** UFH is preferred in acute proximal DVT because: 1. **Rapid onset** — anticoagulation begins immediately 2. **Reversibility** — protamine can reverse if bleeding occurs 3. **Flexibility** — allows transition to thrombolysis if needed 4. **Monitoring** — aPTT titration ensures therapeutic anticoagulation ### Anticoagulation Protocol 1. **UFH bolus:** 80 units/kg IV (typically 5,000–10,000 units) 2. **Continuous infusion:** 18 units/kg/hour, target aPTT 1.5–2.5× control 3. **Overlap:** Start warfarin on day 1–2; continue UFH until INR 2–3 for 24 hours 4. **Duration:** Minimum 5–7 days of parenteral anticoagulation; total 3 months for provoked DVT (immobilization) **High-Yield:** **Proximal DVT** (popliteal, femoral, iliac) requires aggressive anticoagulation; **distal DVT** (calf) may be observed if asymptomatic and no PE risk, but symptomatic distal DVT should also be anticoagulated. ### Adjunctive Measures - **Leg elevation** and **early mobilization** (once anticoagulated) - **Graduated compression stockings** (controversial; may reduce post-thrombotic syndrome) - **IVC filter** only if absolute contraindication to anticoagulation **Warning:** Do NOT use aspirin alone for DVT — it is insufficient. Anticoagulation (not antiplatelet therapy) is the standard of care.