What labs and imaging are needed for a patient presenting with left posterior calf pain and shortness of breath, suggestive of possible deep vein thrombosis (DVT) and pulmonary embolism (PE)?

From the Guidelines

For left posterior calf pain with shortness of breath, I recommend ordering D-dimer, complete blood count, basic metabolic panel, and chest imaging (CT pulmonary angiogram) to evaluate for deep vein thrombosis (DVT) and pulmonary embolism (PE). A lower extremity venous duplex ultrasound should be performed to directly assess for DVT in the painful calf. These symptoms together raise concern for venous thromboembolism, where a blood clot forms in the leg (causing calf pain) and potentially travels to the lungs (causing shortness of breath) 1. If D-dimer is elevated, proceed directly to imaging. For patients with high clinical suspicion, imaging may be warranted regardless of D-dimer results 1. Some key points to consider in the evaluation of suspected DVT and PE include:

• The use of clinical scoring algorithms such as the Wells criteria and the Geneva score to assess pretest probability of PE 1
• The role of D-dimer testing in patients with low or intermediate pretest probability of PE 1
• The appropriateness of CT pulmonary angiography (CTPA) for patients with high pretest probability of PE or those with positive D-dimer results 1
• The potential benefits and limitations of other imaging modalities, such as lower extremity venous duplex ultrasound and ventilation-perfusion scanning 1 Arterial blood gases may help assess oxygenation status, and troponin and BNP can evaluate for cardiac strain if PE is suspected. ECG should be obtained to assess for right heart strain patterns. Oxygen saturation monitoring is essential during the evaluation. This combination of tests allows for prompt diagnosis of potentially life-threatening conditions requiring immediate anticoagulation therapy. It is also important to note that the diagnosis of DVT and PE can be challenging due to the nonspecific nature of the clinical presentation, and a comprehensive evaluation is necessary to ensure accurate diagnosis and effective management 1.

From the Research

Diagnostic Approach

To diagnose a patient presenting with left posterior calf pain and shortness of breath, suggestive of possible deep vein thrombosis (DVT) and pulmonary embolism (PE), the following labs and imaging are needed:

• D-dimer testing to assess the likelihood of venous thromboembolism (VTE) 2
• Ultrasonography, specifically duplex venous scanning, to diagnose DVT, including calf muscle venous thrombosis (CMVT) 3, 4
• CT pulmonary angiography to diagnose PE 2, 5

Laboratory Tests

Laboratory tests, such as D-dimer, can help assess the likelihood of VTE:

• A normal D-dimer can help rule out VTE in patients who are unlikely to have the condition 2
• Elevated D-dimer levels can indicate the presence of VTE, but are not specific to DVT or PE 5

Imaging Studies

Imaging studies are essential for diagnosing DVT and PE:

• Duplex ultrasonography is fairly sensitive in diagnosing CMVT 4
• CT pulmonary angiography can diagnose PE and determine the site of embolism 2, 5
• Ultrasonography can diagnose DVT, including proximal and distal DVT 3, 5

Clinical Presentation

The clinical presentation of DVT and PE can vary, but common symptoms include:

• Calf tenderness and swelling in patients with DVT 4
• Shortness of breath, chest pain, and hemoptysis in patients with PE 2, 6
• Risk factors, such as immobilization, cancer, and previous VTE, can increase the likelihood of DVT and PE 6