Diagnosis of pulmonary embolism

Present opinion combines the diagnosis and management of deep venous thrombosis and pulmonary embolism. Regarding deep venous thrombosis, clinical assessment based on major and minor diagnostic points in combination with ultrasound of the lower extremities showed useful positive predictive values when the clinical assessments and ultrasound were concordant. Subtle calf asymmetry may call attention to the possibility of thromboembolic disease. The prevalence of acute pulmonary embolism at a general hospital was evaluated. Importantly, the prevalence of unrecognized pulmonary embolism at autopsy has not changed in three decades. Further evaluation was made of the alveolar arterial oxygen difference in the diagnosis of acute pulmonary embolism. As with the partial pressure of oxygen in arterial blood, the alveolar arterial oxygen difference is usually abnormal, but a normal value does not exclude pulmonary embolism. The criteria used for a low probability interpretation of ventilation-perfusion lung scans in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) were modified. Criteria for a very low probability assessment (< 10% positive predictive value) were also determined. Progress was made with helical CT and contrast-enhanced electron-beam CT, but with present technology their roles are limited. Selective digital subtraction angiography with a flow-directed catheter was useful in some patients. A strategy for diagnosis of thromboembolic disease that uses serial noninvasive leg tests was described. This strategy reduces the number of pulmonary angiograms required.