For pediatric blood draws in children under 2 years of age, which vein is predominantly used?

For pediatric blood draws in children under 2 years of age, the median cubital vein is predominantly used because it is generally the largest and most accessible vein located in the antecubital fossa (the area of the arm in front of the elbow). This vein has a straight course and is less likely to move during the procedure, reducing the likelihood of complications or the need for multiple attempts. Additionally, the median cubital vein is easily palpated, which is crucial when drawing blood from smaller patients where vein selection can be more challenging due to their smaller size and decreased subcutaneous fat.

While other veins like the femoral vein, radial vein, and cephalic vein can be used in specific circumstances, they are not as commonly utilized for standard blood draws in very young children. The femoral vein, located in the groin, is more invasive and usually reserved for emergency situations. The radial vein, found in the wrist, is typically smaller and can be difficult to access in infants. The cephalic vein is also a possibility, but it is often smaller and can vary significantly in location and size among young children. This makes the median cubital vein the preferred choice due to its size, location, and accessibility.