The full gamut of urolithiasis surgical therapy, including ureteroscopy, shock wave lithotripsy, and percutaneous nephrostolithotomy, was covered in this extensive poster session. With regard to ureteroscopy, the Lower Pole Study Group, organized by Jim Lingeman of Indianapolis, presented sobering data with regard to stone free rates following ureteroscopic therapy for upper tract renal calculi (Abstract 1892). In this multi-institutional study, follow-up CT scans at 3 months, revealed stone free rates of only 63% for patients with stones ≤ 10 mm and only 29% among patients with renal calculi 11-20 mm. In this regard, the question arises whether the recent introduction of ureteral access sheaths could positively impact on the stone free rate. L'Esperance and colleagues at Duke addressed this issue (Abstract 1876) in a retrospective review of 181 patients undergoing ureteroscopic renal stone therapy. They found that the overall stone free rate was significantly (p < .046) better in the access sheath group (79% vs. 67%); the difference tended to be greatest when patients with only a lower pole stone were reviewed (68% vs. 52% stone free). The endourology group at Duke also documented clinically lower intra-renal pelvis pressures when a sheath was used (Abstract 1890). Pressures without a sheath ranged from 60 - 94 mm Hg in the ureter and renal pelvis, whereas with a sheath in place, pressures ranged from 15 - 41 mm Hg. The highest pressures were recorded when the endoscope was in the renal pelvis. All differences at each site achieved statistical significance.
In the realm of shock wave lithotripsy, yet another paper provided data to support a "slow" delivery rate. Chacko and colleagues, using a Doli 50 at the Univ. of Colorado in Denver showed that for calculi 10-20mm in size, a treatment rate of 70-80 shock waves/minute provided for better stone free rates (72%) on a KUB at 1 month than treatment at 120 shock waves/ minute (55% stone free, p < .05) (Abstract 1910). In addition, more articles are beginning to be published regarding predictive parameters for assessing the chances of a patient with a stone becoming stone free with shock wave lithotripsy. Corroborating earlier reports, Pareek and co-authors in New York showed a significant increase in stone free rate when the calculi on CT had a density of only 578 Hounsfield units as opposed to 910 Hounsfield units (Abstract 1887). Furthermore, they showed that the stone free rate fell as the BMI increased. While this favors treating thin patients with less dense calculi, one needs to realize that these thinner patients are at a higher risk than their obese stone-bearing counterparts to develop a post-SWL peri-renal hematoma according to a retrospective study by Dhar and colleagues at the Cleveland Clinic. On a post SWL ultrasound at 4 weeks, a perirenal hematoma was noted in 3.7% of cases (Abstract 1873). In addition to being nonobese, increasing age was also correlated with the occurrence of a post SWL perirenal hematoma.
On the percutaneous front, Kim and colleagues from Indianapolis reported on percutaneous treatment of calyceal diverticulae without retrograde ureteral catheterization or cannulation of the neck of the diverticulum (Abstract 1901). In their report, 20 patients were successfully treated by merely accessing only the diverticulum; following stone removal, a roller electrode was used to electrocoagulate the entire surface of the diverticulum. Neither a neoinfundibulum nor cannulation of the diverticular infundibulum was attempted. Among 14 patients with IVP follow-up, the diverticulum had disappeared in 12 and was decreased in size in the remainder. Overall 17 of 20 patients were rendered stone free during the initial procedure; one underwent a second percutaneous procedure while the other two patients had tiny fragments of 1 mm and 3 mm, each. With this approach, the operative time (average of 54 minutes) was less than half of the time in other reported percutaneous series for treating a calyceal diverticular stone.
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