From the Guidelines
Investigations for pulmonary embolism (PE) should begin with a clinical probability assessment using validated tools like the Wells score or Geneva score, followed by D-dimer testing in patients with low or intermediate probability, as recommended by the American College of Physicians 1. The diagnostic approach for PE involves several steps, including:
- Clinical probability assessment using validated tools like the Wells score or Geneva score
- D-dimer testing in patients with low or intermediate probability
- CT pulmonary angiography (CTPA) as the gold standard imaging test for patients with high pretest probability or those with elevated D-dimer levels
- Ventilation-perfusion (V/Q) scanning as an alternative to CTPA in patients with contraindications to radiographic contrast dye
- Lower limb compression ultrasonography to identify deep vein thrombosis (DVT) as the source of emboli
- Additional investigations, such as ECG, chest X-ray, arterial blood gases, and cardiac biomarkers like troponin and BNP, to help with risk stratification and diagnosis.
According to the European Society of Cardiology guidelines, a strategy based on computed tomographic angiography is recommended, with plasma D-dimer measurement combined with clinical probability assessment as the first step, allowing PE to be ruled out in around 30% of patients 1. The use of age-adjusted D-dimer thresholds (age × 10 ng/mL) is also recommended in patients older than 50 years to determine whether imaging is warranted 1. CTPA is the preferred method of diagnosis when available and there is no contraindication to radiographic contrast dye, while V/Q lung scanning should be used when CTPA is unavailable or contraindicated 1. The diagnostic approach should be tailored to the patient's clinical presentation, risk factors, and comorbidities, with prompt initiation of anticoagulation if PE is strongly suspected while awaiting definitive diagnosis.
From the Research
Investigations for Pulmonary Embolism
Investigations for pulmonary embolism involve various clinical prediction rules to assess the pretest probability of the condition. Some of the commonly used scoring systems include:
- Wells score
- Revised Geneva score
- Simplified Geneva score
- Pisa score
Clinical Prediction Rules
These scoring systems help in stratifying patients into different risk categories, thereby guiding further diagnostic testing and management. The studies have shown that:
- The Wells score is more accurate than the revised Geneva score in predicting pulmonary embolism 2, 3
- The simplified Geneva score has similar efficiency and safety to the Geneva score in excluding pulmonary embolism in association with the D-dimer test 4
- The Pisa score has a relatively higher clinical value in predicting clinical probability of pulmonary thromboembolism in certain populations 5
Diagnostic Accuracy
The diagnostic accuracy of these scoring systems has been evaluated in various studies, with results showing:
- The area under the receiver operating characteristic curve (AUC) for the Wells score ranges from 0.778 to 0.872 6, 2
- The AUC for the revised Geneva score ranges from 0.693 to 0.734 6, 2
- The AUC for the Pisa score is higher than the Wells and revised Geneva score in certain populations 5
Comparison of Scoring Systems
The studies have compared the diagnostic accuracy of different scoring systems, with results showing:
- The Wells score is more effective than the revised Geneva score in discriminating pulmonary embolism in suspected patients 2
- The Pisa score has a relatively higher clinical value than the Wells and revised Geneva score in certain populations 5
- The simplified Geneva score is safe to use in routine clinical practice for assessing pretest probability of pulmonary embolism 4