[Diagnosis of post-operative venous thrombosis using determination of plasma D-dimer].

PURPOSE: The D-Dimer test has been shown to be highly sensitive for the diagnosis of deep vein thrombosis (DVT) and pulmonary embolism. Two automatic quantitative tests giving a rapid response within 10 and 30 minutes have been recently marketed. In the postsurgery situation however, the role of the D-Dimer test remains controversial and the optimal cutoff value remains open. The aim of this study was to determine the cutoff value during the postoperative period.

PATIENTS AND METHODS: One hundred three consecutive patients admitted to surgery were included. In all patients, D-Dimer test was performed every 2 or 4 days from admission to hospital discharge. The Vidas D-Dimer (Biomerieux, Marcy l'Etoile, France) and the STA Liatest D-DI (Diagnostica Stago, Asnières, France) were performed in parallel in all cases.

RESULTS: Thirty-five patients were excluded because the follow-up period was too short. Results suggest that a D-Dimer value below 2 micrograms/ml has a negative predictive value of 100%. A D-Dimer value over 4 micrograms/ml would indicate suspected deep vein thrombosis in half of the cases, even without clinical signs. Dividing the patients into three groups according to the D-Dimer value, the two tests correlated poorly (r = 0.36 and 0.57) in the middle group (between 2 and 3 and between 3 and 4) and correctly for values below 2 or over 4 micrograms/ml (r = 0.83 and 0.78 respectively).

CONCLUSION: These two optimum cutoff values (< 2 micrograms/ml and > 4 micrograms/ml) are useful for determining the need for further explorations for DVT. By limiting need for ultrasonography and contrast venography, the cost-efficacy ratio for the detection of DVT during the postoperative period is greatly improved with the D-Dimer screening strategy.