Is there a time frame in which you would no longer consider a prior vein mapping study reliable and thus recommend repeating the test in a patient with advanced chronic kidney disease who requires evaluation for fistula placement?

As a standard, typically 6 months is the longest I’d consider utilizing a vein mapping; however, the caveat here is to repeat after any hospitalization or known line placements/extensive blood draws. Vein mapping is very low risk and relatively easy to repeat vs the risk of a failure to mature fistu...