In an arteriovenous fistula, the venous needle should be placed in which direction relative to blood flow?

• A. Retrograde
• B. Antegrade
• C. Lateral
• D. Posterior

Answer: (B)

Placing the venous needle in the direction of blood flow (antegrade) ensures the return blood from the dialysis circuit travels with the natural venous flow toward the heart. In an AV fistula, arterial blood is entering the vein and moving downstream toward central circulation, so cannulating downstream in that same direction optimizes clearance and prevents recirculation of already dialyzed血. If the needle were placed opposite the flow (retrograde), blood would tend to recirculate, reducing dialysis efficiency and potentially causing flow disturbances. Lateral or posterior positioning doesn’t address the essential flow direction and won’t maximize the effectiveness of the treatment.