Comparison of the appropriateness of the latex and Elisa plasma D-dimer determination for the diagnosis of deep venous thrombosis.

Thirty-two patients suspected of deep venous thrombosis (DVT) of the leg were evaluated after simple plasma tests (latex D-dimer and Elisa D-dimer) against echography and phlebography as the gold standard of DVT. Seven patients showed negative results in the latter test. The classification conformity between the D-dimer methods amounted 84.4%. With regard to the diagnostic classification a high specificity of 100% was found for the latex D-dimer test at the cut-off level of 450 ng/ml, whereas for sensitivity, 96% was reached. The Elisa D-dimer test was striking by its high sensitivity of 100%, but its low specificity of 28.5%. In summary, these results demonstrate that when there is a suspicion of DVT according to the clinical symptoms, a negative latex test may reject the diagnosis, whereas the latex test is less useful to establish the diagnosis. On the contrary, the Elisa D-dimer test has a too high false-positive rate. The latex D-dimer test seems to be a reliable tool to exclude the diagnosis after which an ascending contrast venography can be omitted.