Diagnosis of deep venous thrombosis and pulmonary embolism. The tests and their limitations

Pulmonary embolism and venous thrombosis are ubiquitous diseases with significant morbidity and mortality and for which successful although risky treatments are available. Accurate diagnosis is therefore necessary and requires testing beyond the physical examination and history. The number of tests proposed over the years compared with the number in current use attests to the problems with the methods. The more definitive tests are also more invasive, riskier, and more expensive. Individual experience in performance and interpretation of the available tests is of great importance in achieving accurate results, and thus the best scheme for investigation of the patient varies from institution to institution. The most accepted and practiced scheme would involve contrast venography as the initial and final test for suspected venous thrombosis, and pulmonary perfusion imaging (with use of chest radiography in all instances and ventilation imaging in most instances) as the screening test for pulmonary embolism, followed by pulmonary angiography when the scan is not definitive or the clinical picture is divergent from the scan results.