-Position the patient as noted above for examination of the femoral vessels. The study begins with an examination of the common femoral vein just distal to the inguinal ligament. The femoral vessels are located just inferior to the inguinal ligament and approximately midway between the pubic symphysis and the anterior superior iliac spine. The femoral artery is usually palpable. This is the initial point of examination.
-Apply gel to the transducer, the patient’s leg, or both, and position the transducer transversely, just distal to the inguinal ligament, as shown below. Remember, the indicator on the probe should point toward the patient’s right. In this transverse view, the vein is imaged in cross-section.

Probe positioning for assessment of the femoral vein.
-Drag or fan the transducer in a cephalad or caudad direction until the junction of the common femoral vein and the greater saphenous vein can be visualized, as shown below. The common femoral artery is lateral to the common femoral vein.

Ultrasonographic image of femoral vessels without compression.

-Using the transducer, apply direct pressure to completely compress the vein.

-If the vein compresses completely, then a DVT at this site can be ruled out.

-Be sure that enough pressure is being applied and being applied evenly. Apply enough pressure so that slight deformation of the artery is noticeable.

-If the vein is still not completely compressible, a DVT is present. See the image below.

Ultrasonographic image of femoral vessels with compression.

-Complete compression of the vein rules out a DVT, while the inability to completely compress the vein rules in a DVT. Thus, compressibility is the rule in/rule out criterion for DVT on ultrasound. (See Results below for more details.)

-Compressibility must be present in both the femoral veins and the popliteal vein. Sometimes, the angle of the transducer may need to be adjusted in order to completely compress the vein. The greater saphenous vein is a superficial vein. A clot in the greater saphenous vein near its junction with the common femoral vein, however, can easily propagate.

-The examination of the common femoral vein should extend from 2 cm proximal to 2 cm distal to the intersection of the common femoral and greater saphenous veins.

-Distal to the greater saphenous vein, the common femoral vein splits into the deep and superficial femoral veins. Despite its name, the superficial femoral vein is indeed a deep vein. Once collapse of both the deep and superficial femoral veins is confirmed, the examination may move on to the popliteal vein.

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