ADVANCES IN BASIC, LABORATORY AND CLINICAL ASPECTS OF THROMBOEMBOLIC DISEASES - NONINVASIVE DIAGNOSIS OF PULMONARY-EMBOLISM

Background and Objective. Pulmonary embolism (PE), with an incidence o f 23 per 100,000 patients per year, is a frequent clinical problem, re sponsible for 200,000 deaths each year in the United States. Pulmonary angiography, the gold standard for diagnosing PE, is invasive, costly and not universally available. Moreover, PE is confirmed in only appr oximately 30% of patients in whom it is suspected, rendering noninvasi ve screening tests necessary. Several strategies have been recently pr oposed to reduce the need for pulmonary angiography in the diagnostic workup of pulmonary embolism. The objective of this article is to anal yze the individual performance of the new diagnostic instruments and t heir combination in rational diagnostic strategies. Methods. The autho r has been working in this field and has contributed original papers o n diagnosis of pulmonary embolism and cost-effectiveness of noninvasiv e diagnostic tests. In addition, the material examined in this article includes articles published in the journals covered by the Science Ci tation index(R) and Medline(R). Results. Several strategies have been recently proposed to reduce the need for pulmonary angiography in the diagnostic workup of pulmonary embolism. The PIOPED study has establis hed the value of ventilation-perfusion lung scan, a normal perfusion l ung scan virtually ruling out PE, whereas a high probability lung scan is considered diagnostic in face of reasonable clinical suspicion. Al l other lung scan results are nondiagnostic. However, clinical evaluat ion, although insufficiently accurate to yield a definitive diagnosis, is probably reliable enough to be used for estimating pretest probabi lity of PE. The combination of a low clinical probability of PE and a so-called low probability lung scan yields a very low posttest probabi lity of PE, thus foregoing the need for pulmonary angiography. Other u seful instrument in patients with nondiagnostic scans is plasma D-dime r (DD) measurement (ELISA assay), which when under a cutoff value of 5 00 mu g/L potentially exclude PE, due to high sensitivity (97%). Conve rsely, venous compression ultrasonography of the lower limbs (US) is h ighly specific (98%) for deep vein thrombosis (DVT), and disclosing a DVT warrants anticoagulant treatment without resorting to angiography. The potential role of echocardiography is also discussed. The rationa l sequence of noninvasive tests is currently under discussion. Perform ing D-dimer and US before lung scan may be the most cost-effective str ategy, pulmonary angiography being performed only in case of an inconc lusive noninvasive workup. Interpretation and Conclusions. Even though PE remains a difficult diagnostic challenge, the availability of nove l noninvasive tests (plasma D-dimer and ultrasonography of the lower l imbs) and the rehabilitation of clinical assessment allow a more ratio nal and sparse prescription of pulmonary angiography. More work needs to be done to assess test performances and refine diagnostic strategie s in distinct patient subgroups, particularly those hospitalized. Scre ening patients with plasma D-dimer and ultrasonography of the lower li mbs may be the most cost-effective strategy, at least in outpatients. (C) 1997, Ferrata Storti Foundation.