Ultrasound-based morphometry of the cephalic vein for cannulation in pediatric patients: a prospective cohort study

Risk factors for difficult cannulation of the cephalic vein in children remain underexplored. This study aimed to perform an ultrasound-based morphometric assessment of the vein in pediatric patients.

An ultrasound examination of the proximal third of the dominant forearm was conducted in the emergency department of a children's hospital using a Philips Lumify device with a linear transducer (4-12 MHz). Measurements included internal vein diameter, depth from the skin surface, and calculated cannula insertion path length for inclinations of 20° and 30°. Demographic and morphometric data were recorded for each patient. The study protocol was approved by the institutional Bioethics Committee (decision number KB/169/2024).

Cephalic vein diameter correlated positively with age (r = 0.52, p < 0.001), height (r = 0.55, p < 0.001), and weight (r = 0.64, p < 0.001). Larger forearm circumference was associated with greater vein diameter (r = 0.60, p < 0.001), increased depth from the skin (r = 0.28, p < 0.01), and longer cannula insertion path length (r = 0.28, p < 0.01). Vein diameter was best predicted by patient weight, whereas prediction of vein depth and cannula insertion path length based on forearm circumference was limited (8% explained variance).

Prediction of vein depth and cannula insertion path length based on demographic and morphometric variables is limited. Ultrasound guidance should be considered to improve first-attempt success and reduce procedural time and trauma in pediatric patients.