Superficial Ulnar Artery Mimicking the Radial Artery During Radial Forearm Free Flap Harvest: A Surgical Pitfall and its Intraoperative Identification - A Case Report.

[BACKGROUND] The superficial ulnar artery is a rare anatomical variant that can be misidentified as the radial artery during radial forearm free flap harvest, potentially leading to ischemic complications. Awareness of this anomaly is crucial for reconstructive surgeons to prevent inadvertent vascular injury. We present a case where intraoperative identification techniques helped distinguish this variant, ensuring a successful surgical outcome.

[CASE PRESENTATION] A 54-year-old male with squamous cell carcinoma involving the upper lip, buccal mucosa, left commissure, and lateral third of the lower lip underwent wide local excision and modified radical neck dissection. Reconstruction was planned using a radial forearm free flap. Preoperative Allen's test confirmed adequate ulnar artery perfusion. During flap harvest, an unexpected arterial structure was encountered superficial to the flexor muscles, initially mimicking the radial artery. Further dissection revealed the true radial artery between the flexor carpi radialis and brachioradialis muscles, confirming the superficial vessel as an anomalous ulnar artery. The superficial ulnar artery was preserved and buried within the flexor muscle bundle to avoid trauma. Postoperatively, the flap showed satisfactory perfusion, and the patient's hand function remained intact.

[CONCLUSIONS] This case highlights the importance of recognizing vascular anomalies during forearm flap harvest to prevent iatrogenic complications. Simple intraoperative techniques, such as careful proximal tracing of vascular bundles and the "tug test," can aid in distinguishing the true radial artery from aberrant vessels. Preoperative vascular imaging may be beneficial in selected cases where anatomical variations are suspected.