The best diagnostic approach to pulmonary embolism is to search for an alternative diagnosis that can be more readily proved. If this is accomplished, the workup for pulmonary embolism can be ended. However, if no other satisfactory explanation can be found in a patient with findings suggestive of, the workup must be pursued to completion. Diagnostic Evaluation Chest Films are nonspecific and insensitive for pulmonary embolism. The chest film may be normal, or it may show an ele vated hemidiaphragm, focal infiltrates, large or small pleural effu sions, or atelectasis.
Electrocardiogram abnormalities are nonspecific.
There is no level of arterial oxygen that can rule out pulmonary embolism. Most patients with pulmonary embolism have a normal arterial oxygen. An elevated gradient is nonspe cific and may be produced by almost any pulmonary disease. The identification of DVT in a patient with signs and symptoms suggesting pulmonary embolism proves the diagnosis of pulmonary embolism. Inability to demonstrate a source of DVT does not significantly lower the likelihood of pulmonary embolism because clinically asymptomatic DVT may not be detectable.