Allen’s Test is a test used in medicine prior to arterial blood gas collection in order to determine normal patency of the ulnar artery. Anatomy of Allen’s Test. The anatomies evaluated in Allen’s Test include both the ulnar and radial arteries. In normal anatomical and physiological function the hand is supplied with blood (perfusion) through the ulnar and radial arteries. If one is occluded, the other provides blood to the hand and maintains perfusion.