American Board of Pathology (ABPath) 2025 – 400 Free Practice Questions to Pass the Exam

An arteriovenous fistula (AVF) is a direct connection between an artery and a vein, bypassing the capillary bed. This unique anatomical configuration creates a type of blood flow that is characterized by high flow and low resistance. In an AVF, the high-pressure arterial blood flows directly into the venous system, leading to increased venous return and altered hemodynamics.

The creation of an AVF can occur either surgically for purposes like hemodialysis or can develop pathologically, such as in cases of trauma. The resulting flow pattern is distinct from typical arterial or venous blood flow due to the unusual connection. This condition often results in a characteristic "thrill" or "bruit" that can be detected on examination, indicative of the turbulent flow generated at the connection point.

In contrast, other conditions like aortic dissection or peripheral vascular disease involve different mechanisms that do not produce the same direct communication between arteries and veins that defines an AVF. The presence of a thrombus represents a blockage, which would further disrupt normal flow and does not facilitate the unique high-flow profile observed in an AVF. Therefore, the relationship of flow specifically linked to an arteriovenous fistula is the correct choice