State-of-the-Art-Review : Exclusion and Diagnosis of Pulmonary Embolism by a Rapid ELISA D-dimer Test and Noninvasive Imaging Techniques within the Context of a Clinical Model

A negative rapid ELISA D-dimer test alone in out patients with a low to moderate clinical probability (CP) on pulmonary embolism (PE) is predicted to safely exclude pul monary embolism. The combination of a negative rapid ELISA D-dimer test and a low to moderate CP on PE followed by compression ultrasonography (CUS) for the detection of deep vein thrombosis (DVT) is safe and cost-effective as it reduces the need for noninvasive imaging techniques to about 50% to 60% of outpatients with suspected PE. A high probability ven tilation-perfusion (VP) scan or a positive spiral CT consistent with PE and the detection of DVT by CUS are currently con sidered to be clear indications for anticoagulant treatment. Sub sequent pulmonary angiography (PA) is the gold standard di agnostic strategy to exclude or diagnose PE in suspected out patients with a negative CUS. a positive rapid ELISA D-dimer test, and a nondiagnostic VP scan or negative spiral CT to prevent overtreatment with anticoagulants. However, the will ingness of clinicians and the availability of resources to per form PA is restricted, a fact that has provided an impetus for clinical investigators to search for alternative noninvasive strat egies to exclude or detect venous thromboembolism (VTE). Serial CUS testing for the detection of DVT in patients with a low to moderate CP on PE and a nondiagnostic VP scan or negative spiral CT is predicted to be safe and will reduce the need for PA to less than 10% or even less than 5%. This noninvasive serial CUS strategy restricts the need for invasive PA to a minor group of patients (<5%) with the combination of a low CP on PE and high probability VP scan or the combi nation of a nondiagnostic VP scan or negative spiral CT and a high CP on PE. Prospective evaluations are warranted to imple ment and to validate the advantages and the disadvantages of the various combinations of nonivasive strategies and to com pare serial CUS testing versus PA in randomized clinical man agement studies of outpatients with suspected pulmonary em bolism.