Tips for locating lower extremity arteries on ultrasound

Arteries are difficult to identify without labels; however, there are a few tricks to keep you on track while evaluating them. First, there are two easy ways to differentiate between veins and arteries on duplex ultrasound:

1. Compression (or the lack of compression)
2. Color

To differentiate arteries from veins on duplex ultrasound, try to compress the vessel. Veins are easily compressible, but arteries are not.

Veins are also a different color than arteries on color flow duplex ultrasound. Veins are blue while arteries are red. It’s important to note that this color setting can be changed, so be sure to check the ultrasound settings when you start!

Next, let’s cover a few tips and tricks for finding specific lower extremity arteries.

To find the common femoral artery (CFA) in a transverse view, look for what is referred to as the Mickey Mouse view. It consists of the CFA, the common femoral vein (CFV), and the saphenofemoral junction (SFJ), with the great saphenous vein in the groin.

When looking for the CFA in a longitudinal view, look for what is commonly referred to as the tuning fork view. The tuning fork view shows the CFA as it bifurcates into the profunda femoris artery (PFA) and superficial femoral artery (SFA) in the groin.

The presence of the femoral vein helps identify the SFA. In a transverse view, the vein is below the artery on the ultrasound screen.

Remember, blue is typically assigned to veins, and red is assigned to arteries on color flow duplex ultrasound. There may be duplicated femoral veins—but they are easy to tell apart from the SFA. As we’ve already covered, not only is the color assignment different, but veins are easily compressible while arteries are not.

In a longitudinal view on ultrasound, a healthy SFA appears as an unremarkable tube. It is recognized by its anatomical location along the length of the medial thigh.

In contrast to the other lower extremity vessels, the popliteal vein appears above the artery on the duplex ultrasound screen, for both the longitudinal and transverse views.

To summarize, to find the CFA, we look for the Mickey Mouse view. To find the SFA, look for the vein underneath the artery. To find the popliteal artery, look for the vein above the artery on ultrasound.

To find the anterior tibial artery (ATA) and the tibioperoneal trunk (TPT), keep moving the probe down the patient’s leg. The distal popliteal artery can be seen as it bifurcates into the ATA and TPT, with the popliteal vein above the artery.

The calf arteries at the ankle are the dorsalis pedis artery (DPA) and the posterior tibial artery (PTA). They are very small arteries that can be identified by two or more compressible deep veins traveling parallel to them.

To find the DPA, place the probe on the anterior ankle and move laterally. If you have trouble finding the artery, try following the same path as an ankle-brachial index (ABI) Doppler pen by starting between the bones of the first two toes and moving proximally. On ultrasound, the DPA will appear very superficial with calcific shadowing underneath, which is caused by an underlying bone.

Similar to the Doppler pen, you can find the PTA behind the medial malleolus. If you cannot see the PTA very well, perform a distal augment, which is a squeeze of the foot. Blood flow in the vein is accelerated by squeezing distally. The veins can be identified by a blue flash on the duplex created by the blood movement. Where there is a vein, an artery is nearby.

The PTA is also superficial and can be easily seen at the ankle level—especially because of the two or more accompanying veins.

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