In graft hemodynamics, inflow obstruction generally refers to a blockage located where?

• A. Blockage within the graft
• B. Blockage after the graft
• C. Blockage before the graft
• D. No blockage; only flow velocity changes

Answer: (C)

Inflow refers to the arterial supply that feeds the graft, coming from upstream before the graft begins. An obstruction in that region means the blockage is proximal to the graft—in the native inflow artery or at the proximal anastomosis—so less blood is able to enter the graft. This is why the best answer is that the blockage is located before the graft.

Blockage inside the graft would be an intra-graft obstruction, and blockage after the graft would be an outflow obstruction. Saying there’s no blockage and only velocity changes would miss the location-based definition of inflow obstruction.