Basic probe positioning and screen orientation for an arterial duplex ultrasound

26th Feb 2021

Positioning the probe during a duplex ultrasound is simple. Every probe has an orientation notch that is a small marker or grooved line on one side of the probe. Begin by holding the probe with the thumb side of your hand near the orientation notch or groove. 

Duplex ultrasound probe with orientation notch. Hand holding probe with the notch oriented towards the thumb side of hand. Illustration.

Figure 1. The duplex ultrasound probe has an orientation notch on one side. When holding the probe, this notch should be oriented towards the thumb side of your hand.

Next, it’s important to realize that there are two planes used for peripheral arterial duplex studies:

  1. Longitudinal 
  2. Transverse 

On longitudinal ultrasound images, the artery looks like a horizontal tube. On the other hand, transverse ultrasound images are a cross-section of the artery. 

Duplex arterial ultrasound images in longitudinal and transverse views.

Figure 2. On duplex ultrasound images, the artery looks like a horizontal tube in the longitudinal view. In the transverse view, the artery is cross-sectioned. 

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How to orient the ultrasound probe

When using the longitudinal orientation, hold the probe so that the orientation notch is pointing towards the patient’s head. When using the transverse orientation, the notch should be towards the patient’s right side. This will orient your screen to the corresponding plane. 

Hand holding a duplex ultrasound probe for a transverse and longitudinal orientation. Illustration.

Figure 3. When using a longitudinal view, hold the probe so that the orientation notch is towards the patient’s head. When using a transverse view, keep the notch pointed towards the patient’s right side.

 

Duplex ultrasound screen orientation 

Longitudinal plane

When looking at the ultrasound screen in the longitudinal orientation, the patient’s head will be to the left of the image and their legs will be to the right. Longitudinal ultrasound images are taken parallel to the vessel—which is why the artery looks like a horizontal tube. 

Keep in mind that velocities are only taken in the longitudinal view. 

Illustration of patient orientation for a duplex ultrasound image in the longitudinal plane.

Figure 4. In the longitudinal view of a common femoral artery, the duplex ultrasound screen is oriented so that the right of the image is cranial, the left is caudad, the top of the image is the patient’s left, and the bottom is the patient’s right. 

Remember, when performing a duplex ultrasound with a longitudinal view, the probe’s orientation notch should be pointing toward the patient’s head. Medmastery note.

Transverse plane

In transverse images, the artery looks like a cross-sectional circle. As such, any plaque jutting out into the lumen can be easily seen. Transverse views are also useful for finding a vessel’s location.

The probe is held perpendicular to the vessel, which provides the sharpest image. The notch is to the patient’s right when using the transverse view. 

Illustration of patient orientation for a duplex ultrasound image in the transverse view.

Figure 5. In the transverse view of a superficial femoral artery, the duplex ultrasound screen is oriented so that the top of the image is cranial, the bottom is caudad, the right of the image is the patient’s left side, and the left of the image is the patient’s right side.

Quick tip to help you find a vessel if you get disoriented. If you are in longitudinal view and you lose track of a vessel, go back into transverse view. It’s much easier to locate a vessel in transverse than it is in longitudinal view. Medmastery note.

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Recommended reading

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