One cause of aneurysms and pseudoaneurysms is

• A. Infection
• B. High blood pressure
• C. Poor rotation of cannulation sites
• D. Venous stenosis

Answer: (C)

Repeated puncture at the same cannulation spot gradually damages the vessel wall. Each needle stick can injure the intima and media, and with ongoing trauma the wall weakens enough to bulge outward (an aneurysm) or to bleed into surrounding tissue that is walled off (a pseudoaneurysm). Rotating cannulation sites distributes the mechanical stress and gives areas time to heal, which markedly lowers the risk of forming these dilations. Infection can cause aneurysms in other contexts, and high blood pressure or venous stenosis affect vessels differently, but the direct, most common cause in dialysis access is not rotating the puncture sites properly.