Linear array vascular probe 6–10 MHz
For morbidly obese patients, consider abdominal probe
Patient positioning
Reverse Trendelenburg or semi-sitting with 30 degrees of hip flexion
Mild external rotation (30 degrees) hip
Probe at medial inguinal crease
Apply generous compression every centimeter
Continue distal to 1-2cm beyond bifurcation of the common femoral vein
Reverse Trendelenburg or semi-sitting with 30 degrees of hip flexion
Mild external rotation (30 degrees) hip
Patient positioning
Prone, decubitus position, or seated on edge of gurney
Knee flexed 10–30 degree
Reverse Trendelenburg
Start with light pressure to better visualize vessels
Apply generous compression over the popliteal vessels to test compressibility
Vein usually superficial to the artery (artery is anterior)
Prone, decubitus position, or seated on edge of gurney
Knee flexed 10–30 degree
Reverse Trendelenburg
DVT ultrasound
Ankle-brachial index
Thromboelastography 
IVC ultrasound
D-dimer
Aortic ultrasound
Bubble study
Age adjusted D-dimer