Do Italian vascular centers look for isolated calf deep vein thrombosis? Analysis of isolated calf deep vein thromboses included in the "Master" Registry

Aim. Two diagnostic imaging strategies for suspected deep venous thrombosis (DVT) in symptomatic patients are currently used: a serial compression ultrasound examination of proximal veins, or a single complete ultrasound investigation of proximal and distal veins. These strategies lead to different results since only the latter allows diagnosis of isolated calf DVT (ICDVT). Methods. We analyzed the approach of Italian centers in looking for ICDVT using the observational MASTER registry which prospectively collected information on patients with acute symptomatic venous thromboembolism. Results. ICDVT was diagnosed in 170 of the 1772 patients with leg DVT (9.6%). The rate of diagnosed ICDVT vs total DVT differed between centers from 0% to 24%. Patients with ICDVT were younger (P<0.0001); diagnosis was more frequently delayed (P<0.0001), temporary risk factors were more frequent, cancer was less frequent (P<0.001), and pulmonary embolism (PE) was more frequent at presentation (P<0.05). More ICDVT patients received LMWH only, not followed by oral anticoagulation (P<0.001). Conclusion. The diagnostic strategy for suspected leg DVT differs greatly among Italian centers. A relatively high rate of PE was recorded in patients with ICDVT for reasons which are open to debate. Prospective, well designed studies on the clinical risks and the need for diagnosing ICDVT, and the advantages/disadvantages of the two diagnostic procedures are urgently needed.