The superficial ulnar artery "trap" and the free forearm flap.

A superficial ulnar artery identified during the elevation of a free forearm flap is reported. This is the second case appearing in the English literature. The free forearm flap is increasingly popular among plastic surgeons, and it is therefore imperative that this anomaly be well recognized because inadvertent injury of this anomalous artery may devascularize the hand. In cadaver dissections, the incidence of this anomaly has been reported to be 3.1%. This variation is probably encountered in clinical practice more commonly, but it is not recognized. Identification of this anomalous artery is facilitated by elevating but not exsanguinating the forearm prior to harvesting the flap.