Surgical Techniques in Urology Use of Antegrade Reverse-thermosensitive Polymer During Percutaneous Nephrolithotomy to Prevent Fragment Migration: Initial Experience Scott M. Cheney and Mitchell R. Humphreys Our objective was to evaluate the feasibility and initial performance of Backstop reverse thermosensitive polymer to prevent antegrade stone fragment migration during percutaneous nephrolithotomy. TECHNICAL Backstop was used during 5 percutaneous nephrolithotomy procedures to prevent stone CONSIDERATIONS migration into the ureter. Backstop was placed into the upper ureter under direct vision with a flexible nephroscope or with fluoroscopic guidance. Ultrasonic lithotripsy was then performed. Each patient was evaluated for the following: stone-free rate (postoperative computed tomography), rate of antegrade fragment migration, need for subsequent procedures, and complication rate. The average stone burden was 806 mm2. Backstop was successfully deployed in all cases. Average procedure length was 106 minutes. Three patients were rendered stone free, 1 patient retained 2 1-mm fragments in the kidney, and 1 patient retained multiple fragments in the kidney, distal ureter, and bladder, all of which were 3 mm) fragments remaining, the 6F ureteral catheter is removed and an antegrade nephrostogram is performed to check for patency of the ureter before nephrostomy tube removal. UROLOGY 83 (2), 2014
Figure 3. Nephroscopy in patient #5. Safety wire extends down ureter (right). Injection catheter seen at ureteropelvic junction (left). Clear BackStop gel distends ureteropelvic junction and upper ureter. (Color version available online.)
The primary end points analyzed were the absence of residual stones, absence of ureteral stone migration, complication rate using the Clavien classification system, and the need for additional procedures. We also measured stone composition operative time and estimated blood loss.
and no patient required a secondary procedure (secondlook PCNL, ureteral stent placement, and ureteroscopy). Individual stone analyses yielded a wide variety of components as described in Table 1. The average stone burden based on surface area was 806 mm2 (range, 1532273 mm2). The average operative time (start of procedure to end) was 106 minutes, which ranged from 37 minutes in patient #5, in which the percutaneous nephrostomy tube was placed preoperatively, to 187 minutes in patient #4, who had the most significant stone burden and required 3 separate percutaneous tracts to access the entire stone burden. Consequently, he also had the most retained fragments. The average estimated blood loss was 70 mL, and no patient required a blood transfusion nor had a significant change in postoperative hemoglobin or electrolytes.
RESULTS
COMMENT
Demographic, preoperative, postoperative, and stone characteristic data for all patients are listed in Table 1. All patients underwent an uneventful PCNL, and BackStop was successfully deployed in each case. Patients #1, #3, and #5 were rendered stone free on the basis of postoperative CT scan. Patient #2 had 2 1-mm retained fragments within the kidney, and patient #4 retained several small (
Figure 3. Nephroscopy in patient #5. Safety wire extends down ureter (right). Injection catheter seen at ureteropelvic junction (left). Clear BackStop gel distends ureteropelvic junction and upper ureter. (Color version available online.)
The primary end points analyzed were the absence of residual stones, absence of ureteral stone migration, complication rate using the Clavien classification system, and the need for additional procedures. We also measured stone composition operative time and estimated blood loss.
and no patient required a secondary procedure (secondlook PCNL, ureteral stent placement, and ureteroscopy). Individual stone analyses yielded a wide variety of components as described in Table 1. The average stone burden based on surface area was 806 mm2 (range, 1532273 mm2). The average operative time (start of procedure to end) was 106 minutes, which ranged from 37 minutes in patient #5, in which the percutaneous nephrostomy tube was placed preoperatively, to 187 minutes in patient #4, who had the most significant stone burden and required 3 separate percutaneous tracts to access the entire stone burden. Consequently, he also had the most retained fragments. The average estimated blood loss was 70 mL, and no patient required a blood transfusion nor had a significant change in postoperative hemoglobin or electrolytes.
RESULTS
COMMENT
Demographic, preoperative, postoperative, and stone characteristic data for all patients are listed in Table 1. All patients underwent an uneventful PCNL, and BackStop was successfully deployed in each case. Patients #1, #3, and #5 were rendered stone free on the basis of postoperative CT scan. Patient #2 had 2 1-mm retained fragments within the kidney, and patient #4 retained several small (
