Background: The superficial radial artery (SRA) is a rare congenital anomaly in the forearm. However, it can be detected incidentally via trauma, intraoperative findings, angiography, or ultrasonography. In addition, intra-arterial infusion of intravenous medications and difficulties in radial artery catheterization may occur in cases of the SRA.
Methods: Between December 2016 and July 2020, anomalous branches of radial arteries were found incidentally in nine patients at the preoperative visit and identified during ultrasound-guided radial artery puncture in 21 patients when radial artery catheterization using the palpation method proved difficult. Ultrasound examinations were performed for diagnosis and evaluation of these 30 patients.
Results: All anomalous branches of the radial artery were SRAs; 11 (37%), 13 (43%), 6 (20%) were present on the right side, on the left side, and bilaterally, respectively. All SRAs ran close to the cephalic vein. The vascular diameters of the radial arteries were the smallest in the radial artery distal to the SRA bifurcation (followed by in the SRA) and the largest in the radial artery proximal to the bifurcation (p < .001). In two cases, color Doppler study revealed that both the blood flow and color Doppler signal of the SRA disappeared with compression of the radial artery proximal to the SRA bifurcation.
Conclusions: Because the SRA runs very close to the cephalic vein, a tourniquet applied to the arm may easily lead to intravenous catheter misplacement into the SRA. In addition, the small radial artery distal to the SRA bifurcation causes difficulty in radial artery catheterization. Furthermore, SRA cases may have falsely normal Allen's test results. Therefore, the authors recommend that the SRA must be identified before vascular puncture for safe vascular catheterization in the forearm.
Keywords: Doppler; Forearm; collateral circulation; peripheral arterial catheterization; radial artery; ultrasonography.