Clinical Evaluation of BackStop in Patients Undergoing Ureteroscopic Lithotripsy

During ureteroscopic treatment for ureteral stones, lithotripsy, irrigation, and
manipulation of the stone often pushes stone away into the kidney itself. This phenomenon is
called retropulsion, which is defined as clinically significant retrograde migration of
stone or stone fragments. Movement of stones retrograde into the renal pelvis could
potentially add and complicate the surgery further. Often scopes need to be changed in order
to reach the stone, and chasing these stones will add time to the surgery and require more
valuable resources. Furthermore, sometimes a second operation will need to be done when
these retropulsed fragments could not be all found and cleaned out.

A number of devices have been developed to prevent such migration including stone baskets
and conical devices. These are wire-based devices which have the potential of injuring the
ureter. Because of safety concerns and that there is limited data available on the
effectiveness of these devices; these are not widely used by urologists. BackStop has
recently been developed as another tool to prevent retropulsion. It is a water soluble gel
that is injected proximal to the stone. This creates a physical barrier that prevents stone
migration during ureteroscopic lithotripsy for ureteral calculus.

Inclusion Criteria:

- patient with solitary ureteral stone ranging from 5mm to 15mm diameter

- able to tolerate general anesthesia

- clinical indication for treatment by ureteroscopic lithotripsy

- must be willing and able to participate in any follow-up visits

- provide informed consent

- have a CT scan demonstrating the stone

Exclusion Criteria:

- patients undergoing extracorporeal shock wave lithotripsy (ESWL) or any other
extracorporeal or percutaneous lithotripsy procedure as primary procedure

- any co-morbidity or condition that would necessitate exclusion of patient (physician
opinion)

- renal or ureteral anatomical abnormality

- multiple stones in the indicated ureter

- stones in the indicated kidney

- patient is immunocompromised

- multiple organ dysfunction syndrome

- has an absolute or relative solitary kidney mass

- >= Stage 3 chronic kidney disease

- bilateral ureteral obstructing stones

- staghorn calculi

- impaction of several stone fragments (Steinstrasse)

- uncorrected coagulopathy/thrombocytopenia

- urethral and/or ureteral stricture

- reconstructive urinary surgery