What is the best next step in managing a 65-year-old man with swelling of his left leg after left hip replacement, with 2+ edema, hypertension, hyperlipidemia, type 2 diabetes, and obesity, on hydrochlorothiazide, amlodipine, metformin, and atorvastatin?

Best Next Step: Duplex Ultrasonography

Duplex ultrasonography is the best next step for this patient with unilateral leg swelling six weeks post-hip replacement. 1

Clinical Reasoning

This 65-year-old man presents with a high pretest probability for deep venous thrombosis (DVT) based on multiple risk factors:

• Recent major surgery (hip replacement 6 weeks ago) contributes 1 point to the Wells score 1
• Entire leg swelling contributes 1 point 1
• Pitting edema confined to the symptomatic leg contributes 1 point 1
• Multiple comorbidities (obesity, diabetes, hypertension) further increase thrombotic risk 1

With a Wells score of ≥3, DVT is likely, and patients with high pretest probability should proceed directly to imaging rather than D-dimer assessment. 1

Why Duplex Ultrasonography is Preferred

Complete duplex ultrasound (CDUS) is the preferred venous ultrasound test for diagnosing acute DVT and should include:

• Compression of deep veins 1
• Evaluation of posterior tibial and peroneal veins 1
• Bilateral common femoral vein spectral Doppler waveforms 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

Why Other Options Are Inappropriate

CTV (CT Venography)

• Not first-line for suspected lower extremity DVT 1
• Exposes patient to radiation and contrast, which is unnecessary when ultrasound is highly effective and readily available 1

Heparin Drip

• Should not be initiated before diagnostic confirmation 1
• Anticoagulation carries bleeding risk and requires definitive diagnosis first 1
• However, once DVT is confirmed, anticoagulation should be initiated promptly to prevent thrombus propagation and pulmonary embolism 1

Plasma D-dimer

• Not indicated in high pretest probability patients (Wells score ≥3) 1
• D-dimer is useful only for ruling out DVT in low-probability patients 1
• In this post-surgical patient with inflammation (hematoma present), D-dimer would likely be elevated regardless of DVT presence, making it non-specific 1

Important Clinical Caveat

The presence of a large hematoma below the surgical incision does not exclude DVT—in fact, post-surgical hematomas can contribute to venous stasis and increase DVT risk. The clean surgical site argues against infection as the primary cause of swelling. 1

Immediate Management After Diagnosis

If DVT is confirmed on ultrasound, anticoagulation should be initiated promptly, taking into account the patient's comorbidities (diabetes, hypertension, obesity) and current medications. 1 The patient's metabolic comorbidities do not contraindicate anticoagulation but require consideration when selecting the specific agent. 1