Stone disease

Abstract

discussion Purpose: Percutaneous nephrolithotomy effectively treats large volume renal calculi but relies on postoperative imaging to judge success. We evaluated the effectiveness of maximizing intraoperative imaging through combined high resolution fluoroscopy and flexible nephroscopy. Materials and Methods: Percutaneous nephrolithotomy was performed cooperatively with a radiologist in an interventional radiology suite equipped with a ceiling mounted, high resolution C-arm. Aggressive rigid and flexible nephroscopy was performed. At the conclusion patients were prospectively classified as radiologically and/or endoscopically stone-free. Postoperative noncontrast CT allowed fragment classification as stone-free, 2 mm or less, 2 to 4 mm and greater than 4 mm. Results: The average stone dimension +/-SEM was 579 +/-77 mm(2) in 25 consecutive renal units. CT demonstrated that 15 renal units (60%) were stone-free after the primary procedure, while 2 (8%), 5 (20%) and 3 (12%) had fragments 2 or less, 2 to 4 and greater than 4 mm, respectively. Of 21 renal units considered endoscopically and fluoroscopically stone-free postoperative CT demonstrated that 6 had residual fragments, of which all were less than 4 mm. All 4 renal units not considered radiologically and endoscopically stone-free had fragments on CT. Intraoperative fluoroscopy after nephroscopy demonstrated fragments in 36% of renal units, of which after further nephroscopy 78% were stone-free on CT. The sensitivity of intraoperative imaging with reference to the gold standard of postoperative CT was 40%, 38% and 100% at thresholds of 0, 2 and 4 mm, respectively. Specificity was 100%, 94% and 95%, respectively. Conclusions: Flexible nephroscopy combined with high magnification rotational fluoroscopy allows sensitive and specific intraoperative detection of residual fragments, enabling immediate removal or the planning of necessary second look nephroscopy. Editorial CommentThe benefit of achieving a stone free state after surgical stone procedures has been amply demonstrated by Streem and others who showed that even small residual stones are associated with a high likelihood of stone growth, eventual development of symptoms or the need for surgical intervention (1). As such, the identification of residual fragments and aggressive removal is strongly encouraged. Unfortunately, accurate identification of residual fragments is typically performed postoperatively, necessitating a second procedure to remove remaining fragments. However, Portis and colleagues showed that the use of high magnification rotational fluoroscopy along with flexible nephroscopy could improve the detection and removal of residual fragments at the time of initial percutaneous nephroscopy and potentially reduce the need for a second operative intervention. With the use of this technique in 22 patients and 25 renal units, 7 of 9 renal units in which residual fragments were detected by high magnification fluoroscopy after endoscopic inspection were rendered stone free. Postoperative CT confirme...