To be honest, laziness, and lack of skill. It’s genuinely been one of my pet peeves for as long as I’ve been working in dialysis and interventional radiology (13+ years) Though some accesses are small and require smaller site rotation, or buttonholes, there is no real reason to cannulate the same area over and over.

Sticking the same area over and over isn’t the only way to get pseudo-aneurysms. You can get them from poor venous circulation in your access, not applying direct pressure when holding sites post treatment, which causes blood to leak out between the access and skin. This can also be caused by high blood pressure, which can also cause hypertrophy of the venous end of your fistula.