Charles G. Marguet

Simultaneous combined use of flexible ureteroscopy and percutaneous nephrolithotomy to reduce the number of access tracts in the management of complex renal calculi

In a joint study between Duke University, North Carolina and London, a simultaneous combination of flexible ureteroscopy and percutaneous nephrolithotomy was used to reduce the number of access tracts required to manage complex renal calculi. This was found to be an effective method which reduced morbidity and blood loss, without increasing operating time, but without increasing stone‐free rates.

A Prospective, Randomized, Double-Blinded Placebo-Controlled Comparison of Extended Release Oxybutynin Versus Phenazopyridine for the Management of Postoperative Ureteral Stent Discomfort

OBJECTIVES Ureteral stents commonly cause lower urinary tract and flank discomfort. We evaluated the use of extended release oxybutynin versus phenazopyridine versus placebo for the management of ureteral stent discomfort after ureteroscopy. METHODS Each of 60 patients who received a unilateral stent after ureteroscopy was given a blister pack containing 21 unmarked capsules of either extended release oxybutynin 10 mg, phenazopyridine 200 mg, or placebo in a prospective, randomized, and double-blinded fashion. Patients were instructed to take 1 capsule 3 times daily immediately after the procedure. Patients were given 50 tablets of oral narcotic to be taken as needed. Patients reported bothersome scores for flank pain, suprapubic pain, urinary frequency, urgency, dysuria, and hematuria on postoperative day 1, day 2, and the day of stent removal. Narcotic use was also recorded. RESULTS Eight patients were excluded from the analysis for stent migration necessitating early removal (1), uncontrollable pain (1), failure to complete blister pack (4), and inability to contact for follow-up surveys (2). There was no difference in bothersome score among the groups for flank pain, suprapubic pain, urinary frequency, urgency, and dysuria. The phenazopyridine group reported less hematuria on postoperative day 1 when compared with placebo, which was statistically significant. The oxybutynin group required fewer narcotics, but this finding was not statistically significant. CONCLUSIONS Although this study failed to show a significant difference in bothersome scores among the groups, the small sample size precludes definitive conclusion. Future studies pooling these data will determine the overall treatment effect and the optimal management of ureteral stent morbidity.

Tissue response to modified shock wave profiles

We have upgraded the original Dornier HM‐3 lithotripter with a reflector insert to modify the lithotripter pulse profile and a piezoelectric annular array (PEAA) generator to produce microsecond tandem pulse lithotripsy. In this talk, we will present results from in vivo animal experiments using a swine model with or without surgically implanted artificial stones in the renal pelvis. Using this animal model, we have compared in vivo stone comminution and tissue injury, respectively, produced by the original versus the upgraded HM‐3 under clinically relevant output settings. It was found that the upgraded HM‐3 could produce significantly improved stone comminution with substantially reduced tissue injury, compared to the original HM‐3. The underlying mechanisms that may contribute to the improved performance and safety of the upgraded HM‐3 will be discussed. [Work supported by NIH DK52985 and DK58266.]