What clinical test is used to determine the patency of the radial and ulnar arteries?

The Allen test is specifically designed to assess the patency of the radial and ulnar arteries. This test is crucial in determining whether there is adequate blood flow to the hand, particularly before procedures such as arterial cannulation or harvesting of the radial artery for grafting purposes.

During the Allen test, the patient is instructed to clench their fist, which occludes the arteries supplying blood to the hand. The examiner then compresses both the radial and ulnar arteries simultaneously. When the patient opens their hand, the examiner releases the pressure on one artery and observes the return of blood flow to the hand. The speed and quality of the color return provide insights into the patency of the artery being tested and the overall collateral circulation available.

This test directly evaluates the vascular supply to the hand in a simple and non-invasive manner, making it a reliable indicator of arterial patency. In contrast, the other options do not provide the same level of specific assessment for the radial and ulnar arteries.