What is the next step in management for a patient with swelling of the left leg, pitting edema, and a history of recent hip replacement surgery, hypertension, hyperlipidemia, diabetes, and obesity?

Order a Complete Duplex Ultrasound of the Left Lower Extremity

The next step is to order a complete duplex ultrasound (CDUS) of the left lower extremity from the inguinal ligament to the ankle to evaluate for deep venous thrombosis (DVT). 1

Clinical Assessment and Risk Stratification

This patient has a high pretest probability for DVT based on the Wells score:

• Recent major surgery within 12 weeks (hip replacement 6 weeks ago): +1 point 1
• Entire leg swollen: +1 point 1
• Pitting edema confined to the symptomatic leg: +1 point 1
• Wells score = 3 (≥2 indicates DVT is likely) 1

Given this likely pretest probability, venous ultrasound is appropriate without requiring D-dimer testing first. 1 Patients with a likely pretest probability of DVT should proceed directly to imaging rather than D-dimer assessment. 1

Why Complete Duplex Ultrasound is the Preferred Test

Complete duplex ultrasound (CDUS) is the preferred venous ultrasound test for diagnosing acute DVT. 1 This examination should include:

• Compression of deep veins from the inguinal ligament to the ankle at 2-cm intervals 1
• Evaluation of posterior tibial and peroneal veins in the calf 1
• Bilateral common femoral vein spectral Doppler waveforms to evaluate symmetry 1
• Popliteal spectral Doppler and color Doppler images 1

Limited protocols that exclude calf veins are not recommended because they require a second study in 5-7 days to safely exclude DVT, which delays diagnosis and treatment. 1

Risk Factors in This Patient

This patient has multiple risk factors that substantially increase her DVT risk:

• Recent hip replacement surgery: Major orthopedic surgery is a well-established DVT risk factor 1, 2
• Obesity: Associated with increased venous stasis and inflammation 3, 4
• Diabetes: Contributes to endothelial dysfunction 3
• Limited mobility post-surgery: Reduces venous return 3
• Presence of hematoma: May indicate local tissue trauma and inflammation 5

Patients with obesity undergoing total hip arthroplasty have significantly higher complication rates, including a 4.2 times higher risk of infection. 4 The combination of obesity and recent hip surgery creates a particularly high-risk scenario for venous thromboembolism. 2, 4

Why Other Diagnoses Are Less Likely But Should Be Considered

While DVT is the primary concern, the ultrasound may also identify:

• Iliopectineal bursa enlargement: Can cause venous obstruction after hip arthroplasty, though this is rare 5
• Hematoma-related venous compression: The noted thigh hematoma could theoretically compress venous structures 5
• Lymphedema: Chronic condition that can complicate post-surgical recovery, though typically develops more gradually 2

The clean surgical site and absence of tenderness make surgical site infection less likely, though infection risk remains elevated in obese patients post-arthroplasty. 4

Critical Pitfalls to Avoid

• Do not delay imaging for D-dimer testing when pretest probability is high (Wells score ≥2) 1
• Do not accept limited ultrasound protocols that exclude calf veins, as this requires repeat imaging and may miss isolated calf DVT 1
• Do not attribute all leg swelling to post-surgical edema without objective testing, especially 6 weeks post-operatively when most surgical edema should have resolved 1
• Do not assume the hematoma alone explains the entire leg swelling, as pitting edema of the entire leg suggests a vascular etiology 1

Immediate Management Considerations

If DVT is confirmed on ultrasound, anticoagulation should be initiated promptly to prevent thrombus propagation and pulmonary embolism. 1 The patient's multiple comorbidities (hypertension, diabetes, obesity) will require careful consideration when selecting anticoagulation therapy. 6