Final answer:
For blood transfusions, a 14-16 gauge needle is typically used because it allows efficient blood flow and causes minimal damage to the blood cells and vein.
Step-by-step explanation:
When blood is administered by IV, the needle/catheter should typically be in the 14-16 gauge range. Gauges in this range are preferred because they are large enough to allow the blood to flow quickly and efficiently into the vein without causing too much damage to the blood cells or the vein itself. Smaller gauges (higher numbers) may be used for people with small or fragile veins, but for standard blood transfusions, a 14-16 gauge needle is standard practice for adults