Ancillary Study of the ULTREC Project

The ULTREC research project is designed to assess the safety of a negative strategy relying on Colour Doppler Ultrasound (CDUS) for excluding the diagnosis of a new thrombosis. The ULTREC project does not take into account the validity of the CDUS positive criteria used to confirm the diagnosis of Deep Vein Thrombosis (DVT) recurrence. The risk of considering only the negative strategy is to ignore the possibility of having an improvement in sensitivity and negative predictive value at the expense of specificity and positive predictive value and therefore to increase the false positive rate leading to an overdiagnosis of recurrence and an overtreatment, and a potential bleeding risk. In the ULTREC-ANCILLARY study, the research will aim at assessing the validity of baseline CDUS positive criteria for the diagnosis of DVT recurrence. As there is no diagnostic standard to which the results could be compared, it is suggested to validate these criteria based on the evolution of the thrombosis on CDUS performed at D90±5. The hypothesis is that an unchanged appearance under anticoagulation would be in favor of sequelae and will invalidate the initial diagnosis (diagnostic failure)