D-DIMER DETERMINATION TO EXCLUDE PULMONARY-EMBOLISM - A 2-STEP APPROACH USING LATEX ASSAY AS A SCREENING TOOL

D-dimer (DD), when measured by a quantitative enzyme-linked immunosorb ent assay (ELISA), is a valuable test to exclude venous thromboembolis m (VTE). However, DD ELISA technique is not appropriate for emergency use and the available agglutination latex assays are not sensitive eno ugh to be used as an alternative to rule out the diagnosis of VTE. Lat ex assays could still be used as screening tests. We tested this hypot hesis by comparing DD levels measured by ELISA and latex assays in 334 patients suspected of pulmonary embolism. All but one patient with a positive (DD greater than or equal to 500 ng/ml) latex assay had DD le vels higher than 500 ng/ml with the ELISA assay. Accordingly, ELISA te chnique could be restricted to patients with a negative result in late x assay. This two-step approach would have spared about 50% of ELISA i n our cohort. In conclusion, our data indicate that a latex test can b e used as a first diagnostic step to rule out pulmonary embolism provi ded a negative result is confirmed by ELISA and the performance of the latex assay used has been assessed properly.