09/01/2026
Technical tip Tuesday for our fellow vascular sonographers! Let’s say you’re scanning an upper extremity artery, and the waveform is monophasic but you see no evidence of disease? Hyperemia is usually the culprit! When you see hyperemic flow in the upper extremities, you can have the patient clench their fist and the waveform goes back to being multiphasic.
What is hyperemic flow? It’s an excess of blood flow in diastole caused by vasodilation. The waveform has a sharp upstroke, sharp downstroke with a dicrotic notch and has forward antegrade flow in diastole. So this makes it monophasic, which is abnormal for an upper extremity. Resistance decreases in our arms when we scan because we are altering patient position, so our hydrostatic pressure changes, causing our resistance to drop. When we clench the fist, this increases the resistance and changes our waveform back to normal!
