Purpose: We compared stone characteristics and outcomes in patients with a single large nonstaghorn renal calculus treated with percutaneous nephrolithotomy in the Clinical Research Office of Endourological Society global study. Materials and Methods: Two statistical analyses were done, including one comparing renal stone size (20 to 30, 31 to 40 and 41 to 60 mm) and the other comparing renal stone site (pelvis, or upper, mid or lower calyx). Surgical outcomes, including operative time, hospital stay, stone-free rate and postoperative fever, were compared between groups. Fitness for surgery was assessed using the American Society of Anesthesiologists scoring system. Severity of postoperative complications was graded with the modified Clavien classification. Results: Of 1,448 stones 1,202 (83%) were 20 to 30 mm, 202 (14%) were 31 to 40 mm and 44 (3%) were 41 to 60 mm. Of the large stones 73% were located in the renal pelvis. A statistically significantly lower stone-free rate, and higher postoperative fever and blood transfusion rates were seen with increased calculous size. With increased American Society of Anesthesiologists score the proportion of large stones in the calyces increased. At a score of III the proportion of large stones in the calyces was more than twice that of stones in the renal pelvis (13.5% vs 5.7%). Generally more patients with large calyceal than large pelvic stones had postoperative complications across the range of Clavien scores from I to IIIB. Conclusions: Calyceal site was associated with decreased fitness for surgery and an increased risk of postoperative complications compared to renal site. An increase in stone size results in a lower stone-free rate, and higher rates of postoperative fever and blood transfusion.

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doi.org/10.1016/j.juro.2011.11.113, hdl.handle.net/1765/67257
The Journal of Urology
Department of Urology