The most common site used for intravenous injection of iodinated contrast agents is:

The antecubital vein is the most commonly used site for intravenous injection of iodinated contrast agents due to its accessibility and size. Located in the bend of the elbow, this vein is often larger and easier to cannulate compared to other options. Its position makes it readily visible and palpable, facilitating easy insertion of an intravenous catheter. This is particularly important in radiologic procedures where quick and effective contrast administration is necessary for optimal imaging results.

In contrast, while other veins such as the femoral vein, subclavian vein, and external jugular vein can be used for intravenous access, they are typically reserved for more specific situations or procedures. The femoral vein is often used in cases requiring central venous access or when access through the upper limbs is not feasible. The subclavian vein, while also suitable for larger volumes of fluids and contrast agents, is more invasive and carries a higher risk of complications, making it less commonly chosen for routine contrast injections. The external jugular vein can also be used but is generally less accessible than the antecubital vein and not as frequently selected for contrast administration during typical radiologic procedures.