Numerous studies have demonstrated excellent diagnostic accuracy of Compression Ultrasonography (CUS) performed by hospitals doctors, skilled and unskilled in Radiology.

Recently, it was demonstrated that adequately ultrasonography-trained General Practitioners (GP) can perform reliable ultrasound to increase the speed and improve the quality of clinical management of various clinical conditions. To date, in the medical literature there are no studies that demonstrate the diagnostic accuracy of GP in performing CUS for the diagnosis of Deep Vein Thrombosis (DVT). Therefore, we plan to perform a prospective, multicenter, cohort study in which a large number of consecutive outpatients with symptoms or signs of DVT are subject to the CUS by the GP with the aim of evaluating the precision and the diagnostic accuracy compared to specialists in vascular ultrasound, which in this case will be the standard of reference.

Inclusion Criteria:

• first episode of DVT of lower limbs

Exclusion Criteria:

• previous episodes of DVT
• ongoing anticoagulation
• age younger than 18 years
• pregnancy

All outpatients evaluated at home or at office by the GP with a first episode of suspected DVT of the lower limbs will be screened with CUS. GP may use his/her own ultrasound, or take advantage of the equipment of the Vascular Service of the Hospital. Shortly afterward, (i.e., within 2 hours), all outpatients will be re-evaluated by a doctor with expertize in vascular ultrasound