Safety of a Management Strategy Based on Colour Doppler ULTrasound and D-Dimer Testing for the Diagnosis Exclusion of RECurrent Deep Vein Thrombosis of the Lower Limbs. The ULTREC Project

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Detailed Summary

The purpose is to assess the safety of a management strategy based on colour doppler ultrasound (CDUS) and D-Dimer test results for the diagnosis exclusion of recurrent deep vein thrombosis (DVT) of the lower limbs. DVT recurrence requires using anticoagulant treatment to prevent thrombosis progression. Given an increased bleeding risk with prolonged treatment, an accurate diagnosis for recurrence is needed. However, the diagnosis of a new thrombosis in a previously involved leg is difficult. Imaging modalities and criteria that are currently used for the diagnosis may be equivocal and unable to discriminate between an old clot and a new one recently developed at the same site. An increase in vein diameter after vein compression by the ultrasound probe was suggested as a diagnostic criterion for a new DVT. This method has many limitations in clinical practice, mainly a lack of availability of a previous measurement and a poor inter-observer agreement. Colour Doppler ultrasound enables to study both the thrombus and the blood flow characteristics that might help to overcome these limitations. CDUS is a well-known method for the diagnosis of vascular diseases and is used in every day clinical practice for the diagnosis of a first DVT and DVT recurrence but CDUS has never been assessed for DVT recurrence in a study. The diagnosis of DVT recurrence may be easily established using the same criteria as for a first DVT episode. Our hypothesis is that CDUS associated with D-Dimer can safely rule out the diagnosis of DVT recurrence while maintaining a good specificity. The strategy consists in performing first a CDUS that helps to classify patients as having (positive CDUS) or not having (negative CDUS) a new thrombosis. In the case of an equivocal CDUS, a D-Dimer test is performed. If the D-dimer is normal, the diagnosis of DVT recurrence is ruled out and the patient is not treated. If the D-dimer is abnormal, the diagnosis cannot be excluded nor confirmed and a second CDUS is performed on D7±2. Meanwhile, patients are not treated by anticoagulants. An unchanged CDUS on D7±2 qualifies patients as free from a new DVT and they are not treated. Conversely a change in CDUS qualifies patients as having a new DVT which requires anticoagulant treatment. All patients have a 3-month follow-up for the assessment of potential venous thromboembolic events.

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