Modified Allen Test

1. Have the patient make a fist and occlude both the ulnar (opposite of thumb side) and the radial

arteries (closest to the thumb) by compressing with two fingers over each artery

2. Have the patient open his or her fist, and observe if the patient’s palm has become bleached of

blood

3. Release the pressure on the ulnar artery (farthest from the thumb) only, and note if blood

return is present. The palm should become perfused with blood. Adequate perfusion is a positive

test indicating the arterial blood may be drawn from the radial artery. Blood should not be taken

if the test is negative