Editing Allen's test (section)

==Method==
===Original test===
The original test proposed by Allen is performed as follows:<ref name="allenoriginal"/>
# The patient is asked to clench both fists tightly for 1 minute at the same time.
# Pressure is applied over the [[Radial artery|radial]] and [[Ulnar artery|ulnar arteries]] simultaneously so as to occlude them.
# The patient then opens the fingers of both hands rapidly, and the examiner compares the colour of both. The initial [[pallor]] should be replaced quickly by [[rubor]].
# The test may be repeated, this time occluding the ulnar arteries.

===Modified test===
In the modified Allen test, one hand is examined at a time:<ref name=":0" />
# The patient is asked to clench their fist for about 30 seconds.
# Pressure is applied over the ulnar and the radial arteries so as to occlude both of them.
# Still elevated, the hand is then opened. It should appear blanched (pallor may be observed at the finger nails).
# Ulnar pressure is released while radial pressure is maintained, and the colour should return within 5 to 15 seconds.

If color returns as described, Allen's test is considered to be normal. If color fails to return, the test is considered abnormal and it suggests that the [[ulnar artery]] supply to the hand is not sufficient.<ref name=":0">{{Cite web|title = Modified Allen test|url = https://www.ncbi.nlm.nih.gov/books/NBK138652/|date = 2010-01-01|last1 = National Center for Biotechnology|agency = U. S. National Library of Medicine|publisher = World Health Organization}}</ref>