Negative Allen's test is indicated by what finding?

Negative Allen's test is indicated by what finding?

• A. Takes longer than 10s to blanch
• B. Blanches within 2 seconds
• C. No blanching occurs
• D. Pain with pressure

Answer: (A)

Allen's test checks whether the hand can be adequately perfused through the radial and ulnar arteries and their collateral pathways. The test is performed by occluding both arteries, then releasing one to see how quickly color returns to the hand. A prompt return of color—typically within a few seconds—means the artery is patent and perfusion is normal through the collateral circle. If blanching is slow, taking extended time (for example, longer than about 10 seconds), it shows that releasing that artery does not re-establish blood flow promptly, indicating impaired arterial inflow or poor collateral circulation. This finding signals an abnormal (positive) test for vascular insufficiency. The other options describe normal perfusion (rapid blanching) or a more extreme failure of inflow (no blanching) or a symptom not used to define the test result.

Allen's test checks whether the hand can be adequately perfused through the radial and ulnar arteries and their collateral pathways. The test is performed by occluding both arteries, then releasing one to see how quickly color returns to the hand. A prompt return of color—typically within a few seconds—means the artery is patent and perfusion is normal through the collateral circle. If blanching is slow, taking extended time (for example, longer than about 10 seconds), it shows that releasing that artery does not re-establish blood flow promptly, indicating impaired arterial inflow or poor collateral circulation. This finding signals an abnormal (positive) test for vascular insufficiency. The other options describe normal perfusion (rapid blanching) or a more extreme failure of inflow (no blanching) or a symptom not used to define the test result.