From the Guidelines
The diagnostic workup for pulmonary embolism (PE) should begin with clinical assessment using validated tools like the Wells score or Geneva score to determine pretest probability, followed by D-dimer testing for patients with low or intermediate probability, and imaging studies such as CT pulmonary angiography (CTPA) for those with high pretest probability or elevated D-dimer, as recommended by the most recent guidelines 1. The clinical assessment is crucial in determining the pretest probability of PE, which guides the subsequent diagnostic steps. For patients with low or intermediate probability, D-dimer testing is a useful initial step; a negative D-dimer can effectively rule out PE in these groups 1. If D-dimer is elevated or if the patient has high pretest probability, imaging studies are necessary.
- CT pulmonary angiography (CTPA) is the gold standard imaging test, offering excellent sensitivity and specificity for detecting emboli in the pulmonary arteries.
- In patients with contraindications to CTPA (such as renal failure or contrast allergy), ventilation-perfusion (V/Q) scanning is an alternative 1.
- Lower extremity compression ultrasonography should be performed to identify deep vein thrombosis (DVT), the most common source of PE. For patients with unexplained or recurrent PE, additional testing may include:
- Thrombophilia screening (factor V Leiden, prothrombin gene mutation, protein C/S deficiency, antithrombin deficiency, antiphospholipid antibodies), particularly in younger patients or those with family history of thrombosis.
- Cancer screening may be warranted in patients with unprovoked PE, especially those over 40, as PE can be the first manifestation of occult malignancy 1. Echocardiography is useful to assess right ventricular function and pulmonary pressures, which helps with risk stratification and management decisions 1. The diagnostic approach should be guided by the most recent and highest quality evidence, prioritizing patient outcomes in terms of morbidity, mortality, and quality of life 1.
From the Research
Diagnostic Workup for Pulmonary Embolism
The diagnostic workup for pulmonary embolism (PE) involves a combination of clinical assessment, laboratory tests, and imaging studies.
- The initial step in the diagnostic workup is to assess the clinical probability of PE using a clinical decision rule, such as the Wells score or the Geneva score 2, 3, 4.
- Patients with a low clinical probability and a normal D-dimer concentration (<500 ng/mL) are considered unlikely to have PE, and further diagnostic testing and anticoagulant therapy can be withheld 2.
- For patients with a moderate or high clinical probability, or those with a low clinical probability and an elevated D-dimer level, further diagnostic testing is necessary 2, 3, 4.
- Imaging studies, such as compression ultrasonography of the legs, multidetector computed tomography angiography, or ventilation-perfusion scanning, can be used to diagnose or exclude PE 3, 4, 5.
- Pulmonary angiography may be necessary in some cases where the clinical suspicion for PE remains high, despite negative results from less invasive studies 4.
Laboratory Tests
- D-dimer testing is a useful tool in the diagnostic workup of PE, as a negative result can help exclude the diagnosis in patients with a low clinical probability 2, 3, 4.
- However, a positive D-dimer result is not specific for PE and can be elevated in a variety of other conditions 5.
Imaging Studies
- Multidetector computed tomography angiography is the diagnostic test of choice for PE when available and appropriate for the patient 4.
- Ventilation-perfusion scanning is an acceptable alternative to computed tomography angiography in select settings 4.
- Pulmonary angiography is the gold standard for diagnosing PE, but it is invasive and usually reserved for cases where the clinical suspicion remains high despite negative results from less invasive studies 4.