Infra-popliteal deep venous thrombi and the risk of symptomatic pulmonary embolism in hospitalized patients.

Infra-popliteal veins include the tibial and peroneal veins, as well as the soleal and gastrocnemial veins collectively known as the calf muscle veins (CMVs). Acute infra-popliteal deep venous thrombi (DVTs) are often considered insignificant with regard to the risk of pulmonary embolism (PE). A retrospective review of 4035 consecutive lower extremity venous duplex scans were made in 3146 hospital patients at our Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL)-accredited vascular lab. Seven hundred sixteen (17.7%) duplex scans were positive for acute DVTs, and 112 (2.8%) were associated with PEs. The breakdown of positive duplexes for acute DVTs was as follows: 202 (28.2%) isolated femoral-popliteal DVTs with PE in 23 (11.4%), 304 (42.5%) isolated infra-popliteal DVTs with PE in 24 (7.9%) and 210 (29.3%) multilevel DVTs involving both vein segments (femoral-popliteal and infra-popliteal) with PE in 38 (18.1%). Of the 304 isolated acute infra-popliteal DVTs, 207 (68.1%) were isolated CMV DVTs with evidence of PE in 12 (5.8%). No statistically significant difference (P = 0.27) in the risk of PE between isolated femoral-popliteal and isolated infra-popliteal DVTs was noted. A significant number of patients (5.8%) with isolated CMV DVTs developed PE. Lower limb venous scans for DVTs should evaluate the infra-popliteal veins. Hospitalized patients with infra-popliteal DVTs should receive anticoagulation.