STONE DISEASE

Determination of ideal stent length for endourologic surgery
Jeon SS, Choi YS, Hong JH
Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
J Endourol. 2007; 21: 906-10

• Purpose: To assess whether direct measurement of ureteral length correlates with patient height or the ureteral length measured on intravenous urography in order to determine the appropriate ureteral stent length to be used for ureteroscopic surgery.
• Patients and Methods: Sixty-five patients (70 ureters) who underwent ureteroscopic procedures were evaluated. The ureteral length between the ureteropelvic and ureterovesical junctions was determined either by preoperative intravenous urography (straight ureteral length; SUL) or intraoperatively with the aid of a guidewire (practical ureteral length; PUL). We regarded the PUL as a clinically useful measurement. The height, SUL, and PUL for each patient was determined. For a postoperative comparison of proper stent position, we selected another 36 patients in whom the length of the stent was based on patient height.
• Results: The SUL values correlated significantly with the PUL (R2 = 0.482 on the right v 0.564 on the left side) and might be used as a predictor of stent length. However, patient height did not correlate with the PUL. Postoperative stent position tended to be better in the patients who had direct ureteral measurements than in those with stents chosen on the basis of patient height.
• Conclusion: Determination of stent length according to patient height does not correlate well with the length needed for endoscopic procedures. Direct measurement of the ureteral length is easy and minimizes stent-associated complications and stent migration.
  
  
• Editorial Comment
  The routine use of noncontrast cross-sectional imaging for the diagnosis and preoperative planning for urolithiasis makes the determination of ureteral length on IVP to a certain degree obsolete. As such, alternative methods to determine ureteral length at the time of surgery are attractive. The concept of direct ureteral length measuring at the end of the procedure is attractive. This can be accomplished as described in this study, by passing a guidewire. Alternatively, one can measure the distance on the ureteroscope as it is withdrawn from the UPJ to the UVJ. Lastly, one could use an open-ended ureteral catheter with inked-measurements. The authors note that ureteral dilation at the end of a ureteroscopic stone extraction could lead to overestimation by the PUL method.
  The stent sizes utilized based on patient height were longer than we would traditionally utilize. For example, we commonly utilize 22 cm stents for patients shorter than 5’4”, and though the shortest patient in this study was 4’8”, the shortest ureteral stent placed was 24 cm.
  The authors’ hypothesis that a poorly placed stent that crosses the midline is somewhat speculative without the evaluation of urinary symptoms and flank pain in this study. One could make a counter-argument that a coil sitting flush on the sensitive trigone could cause more discomfort than one that has extra length in the bladder. As such, the impact of stent positioning on patient outcomes remains an area ripe for investigation.

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA