PLASMA D-DIMER - A USEFUL TOOL FOR EVALUATING SUSPECTED PULMONARY EMBOLUS

Although ventilation-perfusion lung scanning is widely used in evaluat ing patients with suspected pulmonary embolus, additional rapid screen ing tests are needed to supplement scintigraphy in patients in whom th e scan is indeterminate or the scan results are discordant with clinic al suspicion. D-dimer is a fibrin degradation product which should be elevated in the presence of intravascular coagulation. We prospectivel y studied patients referred for lung scanning by obtaining a plasma D- dimer latex agglutination assay at the time of the scan. Of 64 patient s who had pulmonary angiography to confirm the diagnosis, 16 were posi tive for pulmonary embolus and only one had a normal D-dimer. The D-di mer was normal in 27 of 48 patients without embolus and elevated in 21 . Although an elevated D-dimer level is a nonspecific finding, we conc lude that a normal D-dimer is a good negative predictor for pulmonary embolus, with a negative predictive value of 0.97.