| CXR | Normal CXR Plate atelectasis Hampton hump (pleural-based opacity) Small pleural effusion Elevated hemidiaphragm Fleischner's sign (prominent amputated pulmonary artery) Westermark's sign (peripheral oligaemia) The more abnormal the CXR, the less likely is PE Normal CXR in a breathless hypoxic person in the absence of bronchospasm means that PE is likely |
| ECG | Sinus tachycardia Nonspecific T-wave changes P-pulmonale RV strain Right bundle branch block S1, Q3, T3 (deep S-wave in lead I, Q-wave in lead II and T-wave inversion in lead III) ECG is very useful at revealing alternative diagnoses (e.g. myocardial infarction) |
| ABGs | Hypoxaemia, hypocapnia and increased PA–a,O2 Can be normal in PE, especially in young people with good pulmonary reserve |
| d-dimer | d-dimer should always be considered with the clinical probability Negative d -dimer is useful in excluding PE in the setting of low clinical probability and obviate the need for further imaging. d -dimer is not recommended to be used when the clinical probability of PE is high, as it is unlikely to influence the decision for further imaging and would most likely be positive. |
| CUS | Leg ultrasound study can be helpful as an adjunctive test to nondiagnostic imaging (V′/Q′ or CTPA) in diagnosis of PE. |
| V′/Q′ | A high V′/Q′ probably indicates that PE is very likely, especially when combined with a high clinical probability. Normal or near-normal V′/Q′ scan virtually excludes PE. Nondiagnostic scans occur in most of the patients undergoing V′/Q′ scanning, especially when there is cardiopulmonary disease or abnormal CXR; these patients should be investigated further |
| CTPA | CTPA is easier to read than V′/Q′ scans, even in the presence of cardiopulmonary disease or abnormal CXR; CTPA has now replaced V′/Q′ scanning as the screening diagnostic test for PE in many institutions The diagnosis of PE using CTPA can be improved if CUS is used as an adjunctive test and clinical probability is taken into account. It is safe to withhold anticoagulant therapy after a negative CTPA and a negative CUS if the clinical probability is low. It is also probably safe to withhold anticoagulant therapy after a negative CTPA and a negative CUS with intermediate clinical probability, although this approach should be considered with caution. The chance of missing PE with a negative CTPA and a negative CUS in patients with high clinical probability is relatively high and further evaluation is warranted in these patients. |
| Troponin-T and -I | Can be raised in severe PE Can not be used to rule out PE, but can be used in risk stratification of PE to identify low-risk patients with PE who can be treated as outpatients |
| BNP | Elevated levels of BNP are associated with RV dysfunction in PE It can be used in risk stratification of PE severity |
CXR: chest radiography; RV: right ventricular; ABG: arterial blood gas; PA–a,O2: alveolar–arterial oxygen tension difference; CUS: compression ultrasound; V′/Q′: ventilation/perfusion; CTPA: computerised tomographic pulmonary angiography; BNP: B-type natriuretic peptide.