STONE DISEASE

Secondary signs of non-enhanced CT prior to laser ureterolithotripsy: is treatment outcome predictable?
Seitz C, Memarsadeghi M, Fajkovic H, Tanovic E
Rohrbacher Str. 8, Medical University of Vienna, Austria
J Endourol. 2008; 22: 415-8

• Purpose: To correlate the presence of secondary signs of non-enhanced computed tomography (NECT) in renal units harboring ureteral calculi with intraoperative findings and treatment outcome after holmium:yttrium-aluminum-garnet laser (Ho:YAG) ureterolithotripsy.
• Subjects and Methods: Two-hundred patients were prospectively included after ureteral calculi were detected on NECT. All patients underwent Ho:YAG ureterolithotripsy at the Medical University of Vienna. All CT studies were reviewed by one specialized uroradiologist blinded to pre- and postoperative parameters for secondary signs as renal enlargement, perinephric stranding, ureteral dilation, periureteral edema, and ureteral rim sign. The impact of secondary signs on intraoperatively-verified impaction and treatment outcome was evaluated.
• Results: Of the 200 patients 85 (42.5%) harbored proximal and 115 (57.5%) harbored distal ureteral calculi. The stone-free rates for proximal and distal calculi were 80% and 97%, respectively. Although proximal stone location and intraoperatively-verified impaction correlated significantly with stone-free rates (P < 0.0001, P = 0.01), the presence of secondary signs could not predict intraoperatively-verified stone impaction or stone-free rates (renal enlargement: P = 0.2, P = 0.5; perinephric stranding: P = 0.7, P = 0.5; ureteral dilation: P = 0.7, P = 0.7; periureteral edema: P = 0.8, P = 0.06; ureteral rim sign: P = 0.8, P = 0.3).
• Conclusion: Preoperative secondary signs seen on NECT in patients harboring ureteral calculi do not correlate with intraoperative findings of impaction, and do not predict treatment outcome after Ho:YAG ureterolithotripsy.
  
  
• Editorial Comment
  Previous studies have demonstrated that patients with secondary signs of obstruction on CT scan imaging are more likely to require surgical intervention. It would be helpful if CT scan findings could predict the success rate with ureteroscopic lithotripsy. As such, the success rates are high and complication rates uncommon with Holmium laser lithotripsy, therefore the likelihood of identifying preoperative prognostic factors is low.
  The low level of success with proximal ureteral stones could be related to the reliance on semi-rigid ureteroscopy in this study - the addition of flexible ureteroscopes and stone retrieval devices may have helped improve success rates. As such, the impact of proximal ureteral stone location and endoscopic evidence of impaction may warrant further evaluation using these two modalities.
  The authors report that over one-third of patients had stone impaction at the time of ureteroscopy, as defined by adherence to the ureteral wall necessitating detachment with the Holmium laser. In our experience, the risk of impaction appears related to the duration of symptoms and obstructions. Indeed, it is surprising that such a high rate of impaction was detected as the median time to intervention was only 2 days after imaging.

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA
E-mail: endourol@yahoo.com