Clinical Evaluation of BackStop in Patients Undergoing Ureteroscopic Lithotripsy

Post FDA-Approval Clinical Evaluation of BackStopTM in Patients Undergoing Ureteroscopic Lithotripsy: A Prospective, Randomized Clinical Trial

The purpose of this clinical study is to evaluate BackStop, a polymer-based device that is intended to be used during ureteroscopic lithotripsy to prevent retrograde stone migration.

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.

Patients randomized to the Experimental arm will receive the BackStop gel during their ureteroscopic lithotripsy to prevent retrograde migration of stones or stone fragments.

Patients randomized to the control group will not use any devices to prevent retrograde migration of stones and stone fragments during their ureteroscopic lithotripsy.

BackStop™ is a FDA approved device. It is intended for use during ureteroscopic lithotripsy to prevent retrograde migration of stones and stone fragments. It is comprised of a solution of a thermosensitive polymer, a purified version of poloxamer 407 having been fractionated in saline. BackStop™, which is injected above the stone, is provided in sterile, pre-filled 2.5ml and 5ml syringes along with and a corresponding injector and a catheter (3F or 5F).

Time required to deliver BackStop beginning with insertion of BackStop catheter and ending with its removal subsequent to the delivery of BackStop

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

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