Deep Venous Thrombosis (DVT)

A 50 year old male presents to the emergency department with right calf pain and swelling on the third postoperative day. He recently underwent open cholecystectomy 3 days ago. He has a history of hypertension treated with amlodipine. On examination, there is calf tenderness on palpation. Vital signs show blood pressure of 120/80 mm Hg, pulse rate of 88 beats per minute, respiratory rate of 18 breaths per minute, oxygen saturation of 92 percent on room air, and temperature of 97.9 F. D dimer is elevated. Duplex ultrasound shows a thrombus with lack of compressibility and filling defects in the right lower extremity. Diagnosis?

Diagnosis is Deep vein thrombosis.

1. Definition

Deep vein thrombosis is the formation of a thrombus in the deep venous system, most commonly in the lower extremities, and is part of the spectrum of venous thromboembolism.

2. Etiology and Risk Factors

1. Virchow triad
• Venous stasis such as postoperative immobility
• Endothelial injury from surgery
• Hypercoagulability
2. Additional risk factors
• Recent surgery and hospitalization
• Malignancy
• Obesity and advanced age
• Pregnancy or estrogen therapy
• Inherited thrombophilia

3. Pathophysiology

1. Thrombus formation occurs in low flow venous sites, often in calf veins
2. Initiated by endothelial injury, stasis, and hypercoagulability
3. Leads to venous obstruction and inflammation
4. Thrombus may propagate proximally, increasing risk of pulmonary embolism

4. Clinical Features

1. Unilateral calf pain and swelling
2. Tenderness and warmth
3. Erythema and dilated superficial veins
4. May be asymptomatic in up to 50 percent of cases

If pulmonary embolism develops:
5. Shortness of breath
6. Pleuritic chest pain
7. Tachycardia and hypoxia

Homans sign is not reliable and is not recommended

5. Diagnosis

5.1 Clinical Probability

1. Wells score
• ≥2 indicates likely DVT
• <2 indicates unlikely DVT

5.2 Laboratory

1. D dimer is highly sensitive but not specific
2. Used to exclude DVT in low probability patients

5.3 Imaging

1. Compression duplex ultrasound is the diagnostic test of choice
2. Findings include
• Non compressible vein
• Intraluminal thrombus
• Filling defects

6. Management

1. Anticoagulation is the cornerstone of treatment
• Direct oral anticoagulants such as apixaban or rivaroxaban are first line
• Alternatives include LMWH followed by warfarin
2. Duration of therapy
• Typically 3 to 6 months
• Longer for unprovoked or recurrent DVT
3. Thrombolysis
• Reserved for selected patients with extensive proximal or iliofemoral DVT and low bleeding risk
4. Inferior vena cava filter
• Only if anticoagulation is contraindicated or ineffective

7. Prevention

1. Pharmacologic prophylaxis
• LMWH or fondaparinux
2. Mechanical methods
• Sequential compression devices
• Graduated compression stockings
3. Early ambulation after surgery

8. Complications

1. Pulmonary embolism
2. Post thrombotic syndrome
3. Recurrent thrombosis
4. Phlegmasia cerulea dolens, a severe limb threatening form

9. Key Clinical Insight

Postoperative patient with unilateral calf pain, swelling, and non compressible vein on ultrasound strongly indicates deep vein thrombosis

10. Exam Level Pearls

1. Most DVTs originate in calf veins and may propagate proximally
2. Proximal DVT has higher risk of pulmonary embolism than distal DVT
3. Clinical signs alone are not sufficient for diagnosis
4. D dimer is useful only in low risk patients
5. Compression ultrasound is the test of choice