Diagnosis of venous thrombosis and pulmonary embolism.

Venous thrombosis and pulmonary embolism are closely related disorders. As many as 70 to 80% of patients with pulmonary embolism have associated proximal deep venous thrombosis. The clinical diagnosis alone of both venous thrombosis and pulmonary embolism is inaccurate because of the insensitivity and nonspecificity of findings, a problem that also occurs with a variety of other disorders. Invasive, objective tests are still the reference standard, but they are not always easy to perform, they cannot be used for a considerable number of very ill patients, and they create some patient discomfort. There is an increasing trend toward using noninvasive methods, either alone or in combination. These methods entail less risk, can be performed more quickly and conveniently, and are usually more cost-effective. Practical approaches to diagnosing venous thrombosis and pulmonary embolism in the clinical setting are discussed.