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 outpatients with a low to mode rate clinical probability (CP) on pulmonary embolism (PE) is predicted to s afely exclude pulmonary embolism. The combination of a negative rapid ELISA D-dimer test and a low to moderate CP on PE followed by compression ultras onography (CUS) for the detection of deep vein thrombosis (DVT) is safe and cost-effective as it reduces the need for noninvasive imaging techniques t o about 50% to 60% of outpatients with suspected PE. A high probability ven tilation-perfusion CVP) scan or a positive spiral CT consistent with PE and the detection of DVT by CUS are currently considered to be clear indicatio ns for anticoagulant treatment. Subsequent pulmonary angiography (PA) is th e gold standard diagnostic strategy to exclude or diagnose PE in suspected outpatients 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 willingness of clinicians and the availability of resources to per- form PA is restricted, a fact that has provided an im petus for clinical investigators to search for alternative noninvasive stra tegies to exclude or detect venous thromboembolism (VTE). Serial CUS testin g 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 w ill reduce the need for PA to less than 10% or even less than 5%. This noni nvasive serial CUS strategy restricts the need for invasive PA to a minor g roup of patients (<5%) with the combination of a low CP on PE and high prob ability VP scan or the combination of a nondiagnostic VP scan or negative s piral CT and a high CP on PE. Prospective evaluations are warranted to impl ement and to validate the advantages and the disadvantages of the various c ombinations of nonivasive strategies and to compare serial CUS testing vers us PA in randomized clinical management studies of outpatients with suspect ed pulmonary embolism.