What factor is associated with a higher risk of occlusion of anastomoses in a free flap?

The factor associated with a higher risk of occlusion of anastomoses in a free flap is vessel size discrepancy. When there is a significant difference in the diameters of the vessels being anastomosed, it can lead to multiple complications, including turbulent blood flow, inadequate healing at the anastomosis site, and ultimately, a higher likelihood of thrombosis or occlusion.

Size mismatches can create areas of shear stress and can result in inadequate surgical technique during the anastomosis, as the smaller vessel may not adequately accommodate the larger vessel's blood flow or vice versa. This turbulence can compromise the microcirculation, leading to inadequate perfusion of the flap.

In contrast, while factors such as vessel length discrepancy, location, and age can influence the success of free flap surgeries, vessel size plays a more critical and direct role in the hemodynamics of the anastomosis. Ensuring that the sizes of the vessels are compatible is thus a crucial aspect of achieving successful vascular anastomosis in free flap procedures.