Possibility of Access Sheath Placement
Introducing a Ureteral Access Sheath (UAS)
When, after placing a stiff guidewire into the ureter, the ureteral orifice opens like a “tent,” there is a good chance of being able to place a UAS (especially 10/12 Fr).
If just a guidewire (≈3 Fr) fits in the ureteral orifice, there is no need to try.In this case, the sheathless technique or prestenting the patient is the better option.