The Allen’s test: revisiting the importance of bidirectional testing to determine candidacy and design of radial forearm free flap harvest in the era of trans radial endovascular access procedures

Abstract Background The radial forearm free flap is a workhorse free flap. The radial artery, which supplies it, is increasingly being used for endovascular access. A complication of this is radial artery occlusion. Although often asymptomatic it can compromise future free tissue transfer. Case Presentation Two patients who underwent RFFF harvest for head and neck reconstruction are presented; both of who likely had distal radial artery occlusion. The first patient had failure of flap perfusion, presumed secondary to radial artery occlusion from prior endovascular access at the distal radial artery. In the second case, we used the Allen’s test in reverse to identify the same scenario and successfully redesigned the harvest. Conclusion The Allen’s test is a simple bedside test that should be performed bidirectionally to exclude radial artery occlusion, which may compromise flap harvest. Radial artery occlusion will become increasingly common as the radial artery is used more frequently for endovascular access procedures