Dorsal metacarpal veins: anatomic variation and potential clinical implications

The dorsal metacarpal veins are frequently cannulated. Cannulation success is determined by several variable anatomic features. The objective of this study is to classify, for the first time, the anatomic variants of the dorsal metacarpal veins. In this cross-sectional study, 520 university students and staff were conveniently recruited. The dorsal metacarpal veins in 1040 hands were studied. Venous visibility was enhanced by either tourniquet application or near-infrared illumination. Variant patterns of the dorsal metacarpal veins were classified. The final analysis included 726 hands, for an exclusion rate of 30 %. Eight pattern types were identified. Three anatomic features informed the variation. Bilateral symmetry of the dorsal metacarpal veins was present in 352 participants (83 % of the total). The overall frequency distribution of variants in both hands was similar (P = 0.8). The frequency distribution of variants was subject to sexual dimorphism (P = 0.001), ethnic variation (P < 0.001), and technical variation (P < 0.001). The anatomic variants of the dorsal metacarpal veins were sorted into decreasingly frequent primary, secondary, and tertiary groups. The groups may signify a progressive increase in difficulty of peripheral cannulation, in the mentioned order. As such, primary patterns are the most common and likely the easiest to cannulate, while tertiary patterns are the least common and likely the most difficult to cannulate. The preceding premise, in tandem with the bilateral asymmetry of the veins, is clinically significant. With cannulation difficulty likely signifying an underlying tertiary pattern, the contralateral dorsal metacarpal veins are probabilistically characterized by a primary pattern and are, as such, the easier option for peripheral venous cannulation.