Which value is the highest among standard venous diameter thresholds used in an access graft?

• A. Greater than or equal to 2.5 mm
• B. Greater than or equal to 4 mm
• C. Greater than or equal to 2 mm
• D. Greater than or equal to 6 mm

Answer: (D)

In dialysis access planning, larger venous caliber is preferred for grafts because a bigger vein can handle the higher, sustained flow and repeated needle cannulation that a prosthetic graft requires, with a lower risk of thrombosis and early failure. Vein size thresholds used during mapping guide whether a graft is likely to mature and function well; the bigger the threshold, the more favorable the anatomy needs to be.

Among the given values, 6 mm is the highest standard threshold. Veins meeting or exceeding this size are considered most suitable for reliable graft function. The smaller thresholds serve other contexts, such as fistula planning, and don’t indicate as robust a diameter for graft durability.