This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Allen's test is associated with: September 2012 
Select and explain. 
A. Brachial aery, B. Popliteal aery, C. Dorsalis pedis aery, D. Radial aery
D: Radial aery
Answer: D: Radial aery 
Explanation: Ans. D i.e. Radial aery Allen's test The hand is elevated and the patient/person is asked to make a fist-for about 30 seconds. Pressure is applied over the ulnar and the radial aeries so as to occlude both of them. Still elevated, the hand is then opened. It should appear blanched (pallor can be observed at the finger nails). Ulnar pressure is released and the colour should return in 7 seconds. Inference: Ulnar aery supply to the hand is sufficient and it is safe to cannulate/ prick the radial If color does not return or returns after 7-10 seconds, the test is considered positive and the ulnar aery supply to the hand is not sufficient. The radial aery therefore cannot be safely pricked/ cannulated.