Diagnosis of pulmonary embolism

Conventional pulmonary arteriography for the diagnosis of pulmonary embolism (PE) bears several limitations in clinical practice, basically due to its invasiveness. On the other hand, no single noninvasive test is both sensitive and specific for the diagnosis of PE. Therefore, the choice of available noninvasive diagnostic tests guided by the clinical probability of PE is a good compromise at present. The first necessary step toward the diagnosis of PE is to raise the clinical suspicion, given that no diagnosis can be made if PE is not considered in the differential diagnosis of patients with acute cardiorespiratory symptoms. Second, empirical or standardized rules for predicting clinical probability may be combined with one or more noninvasive tests with the aim of increasing the accuracy of the noninvasive diagnosis. The strategy for the noninvasive diagnosis of PE varies among different centers according to the availability of each single technique that may be integrated with another and according to the characteristics of the population that refers to each single center. Therefore, spiral CT should not be used as a primary tool for the diagnosis of PE; its role needs to be re-evaluated in light of its sensitivity, feasibility, and radiation burden on the patients. In patients in whom the diagnosis of PE cannot be made at the end of the noninvasive pathway, the use of the invasive techniques must be taken into consideration. In our experience, however, such cases should not exceed 15 to 20% of the total patient population.