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Stone disease

UROLOGICAL SURVEY

Stone disease

A prospective randomized controlled trial on ureteral stenting after ureteroscopic holmium laser lithotripsy

Cheung MC, Lee F, Leung YL, Wong BB, Tam PC

Division of Urology, Department of Surgery, The University of Hong Kong, Tung Wah Hospital, Hong Kong

J Urol. 2003; 169: 1257-60

PURPOSE: A prospective randomized controlled trial was conducted to evaluate whether postoperative ureteral stenting is necessary after ureteroscopic laser lithotripsy. Materials and Methods: A total of 58 patients with unilateral ureteral stones were randomized into either stented or unstented groups. Ureteroscopic laser lithotripsy was performed using a semirigid ureteroscope (6.5 / 7Fr) and holmium laser without ureteral orifice dilation. There were no selection criteria regarding stone size, location, preoperative ureteral obstruction and hydronephrosis. Endoscopic evidence of stone impaction or mucosal edema/damage did not exclude a patient from the study. Ureteral perforation on completion retrograde pyelogram was the only intraoperative criterion for study exclusion. Postoperative pain scores and symptoms were recorded. Excretory urography was performed to document stone-free status and stricture formation. Radionuclide scan was performed selectively to exclude functional obstruction when ureteral narrowing was found on excretory urogram.

RESULTS: Mean stone size +/- SD was 9.7 +/- 4.0 mm. (range 4 to 27). Proximal ureteral stones accounted for 43% of all stones. Stented and unstented groups were comparable with respect to demographic data, stone parameters, preoperative obstruction and hydronephrosis. There was no significant difference in operating time, laser energy used, stone impaction and mucosal edema/damage between the 2 groups. Postoperative pain and symptoms were more severe and frequent (p < 0.05) in the stented group. However, there was no difference in the incidence of postoperative sepsis and unplanned medical visits. The stone-free and stricture formation rates showed no statistical difference between the 2 groups.

CONCLUSIONS: Ureteral stenting is not necessary after uncomplicated ureteroscopic laser lithotripsy for ureteral stones. Ureteral stent increases the incidence of pain and urinary symptoms but does not prevent postoperative urinary sepsis and unplanned medical visits. Severity of preoperative obstruction and intraoperative ureteral trauma were not shown to be determining factors for stenting.

Editorial Comment

Historically, placement of a ureteral stent after ureteroscopy for stone removal or fragmentation has been routine practice. However, recent retrospective studies and prospective, randomized trials have suggested that placement of a ureteral stent after uncomplicated ureteroscopy may be unnecessary and is associated with greater patient discomfort. The problem lies in what constitutes "uncomplicated". Some investigators restricted their series to distal ureteral calculi only. Others excluded patients requiring balloon dilation of the intramural ureter. Still others excluded patients in whom fragments were extracted after fragmentation, while others excluded patients in whom fragments were left behind! In all cases, it was left to the discretion of the surgeon to exclude patients in whom evidence of mucosal trauma or severe impaction were present. Thus, guidelines for selection of patients who may be safely left unstented are not clear-cut.

The authors of the present randomized trial excluded patients intraoperatively only if the stone was unable to be accessed, a concomitant ureteral stricture was present or a ureteral perforation occurred. Degree of pre-operative obstruction, stone impaction and ureteral trauma or edema did not constitute grounds for exclusion. Furthermore, middle and proximal ureteral stones comprised 59% and 28% of stones in the unstented and stented groups, respectively. Similar to other studies, the authors found no significant difference in stone free rates, post-operative fever or urinary tract infection, or need for unplanned medical visits in the 2 groups. However, also in common with other studies, urinary symptoms were greater in the stented group compared with the unstented group. This study confirms the safety of stentless ureteroscopy after treatment of stones in all locations in the ureter, but also suggests that the appearance of the ureter after stone removal, provided a perforation has not occurred, is not a reliable indicator of ureteral obstruction post-operatively. Hopefully, with additional confirmation and further study, specific criteria for post-operative stenting can be provided. However, it should be kept in mind that in cases of questionable ureteral injury, placement of a ureteral stent will never be the wrong thing to do.

Dr. Margaret S. Pearle

Associate Professor of Urology

University of Texas Southwestern Med Ctr

Dallas, Texas, USA

Characterization of intrapelvic pressure during ureteropyeloscopy with ureteral access sheaths

Rehman J, Monga M, Landman J, Lee DI, Felfela T, Conradie MC, Srinivas R, Sundaram CP, Clayman RV

Department of Surgery, Division of Urologic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA

Urology 2003; 61: 713-8

OBJECTIVES: To evaluate the impact of the ureteral access sheath on intrarenal pressures during flexible ureteroscopy in light of the recent resurgence in their use. As such, using human cadaveric kidneys, we studied changes in intrarenal pressure in response to continuous irrigation at different pressures with and without access sheaths of various sizes and lengths.

METHODS: This study was performed using seven cadaveric kidneys. In three kidneys the study was done in situ with a 7.5F flexible ureteroscope (URS) passed by itself and then passed through a 10/12F sheath (35 and 55 cm in length), whereas, in four kidneys, due to narrowing of the intramural ureter, the study was done ex vivo using the unsheathed URS and then passing the 7.5F flexible URS via the 10/12F, 12/14F, and 14/16F sheaths (all 35 cm in length). A 10F Cope loop pyelostomy was placed to measure intrapelvic renal pressure. Three sets of 3-minute readings (i.e., flow and intrarenal pressure) were taken with the tip of the URS at the distal ureter, middle ureter, and renal pelvis (just above the ureteropelvic junction); the entire process was done at three different irrigant pressure settings: 50, 100, and 200 cm H(2)O. Irrigant flow and intrarenal pressures were measured at all three settings using the URS passed without a sheath and then with the URS passed through the various sheaths positioned at the distal ureter, middle ureter, and renal pelvis.

RESULTS: With all of the sheaths, intrapelvic pressure remained low (less than 30 cm H(2)O), and there was a 35% to 80% increase in irrigant flow versus the control unsheathed URS. With the sheath in place, the majority of the irrigant drained alongside the URS and out the sheath. Flow and pressure with the 12/14F sheath were equivalent to the 14/16F sheath.

CONCLUSIONS: The 12/14F access sheath provides for maximum flow of irrigant while maintaining a low intrarenal pelvic pressure. Even with an irrigation pressure of 200 cm H(2)O, renal pelvic pressure remained below 20 cm H(2)O.

Editorial Comment

Ureteral access sheaths have long been available to facilitate access to the ureter and collecting system. However, a cumbersome design and the potential for ureteral perforation prevented the sheath from achieving widespread use. Resurgence in interest in the access sheath occurred with advances in design that improved ease and safety of placement and reduced the tendency of the sheath to buckle. Although the ureteral access sheath has been used primarily to facilitate multiple entries and exits from the ureter and it has been proven advantageous in this regard from the standpoint of operative time and cost, Rehman and colleagues have shown that use of the access sheath is advantageous for physiologic reasons as well. Using a variety of sizes of access sheaths and irrigation pressures in a cadaveric model, these investigators demonstrated that renal pelvic pressure could be kept below 30 cm H2O and irrigation flow could be improved by 35-80% compared to ureteroscopy without a sheath.

With an increase in the complexity of ureteroscopic procedures has come an increase in operative time. Furthermore, the treatment of larger stones and potentially infected stones has led to an increase in the potential for urinary extravasation and sepsis. The findings of this study suggest that use of a ureteral access sheath, particularly during lengthy ureteroscopic procedures for large renal or ureteral calculi may reduce intrarenal pressure, thereby reducing the likelihood of pyelovenous or pyelolymphatic backflow, as well as the chance of forniceal rupture, extravasation and sepsis, and also improve endoscopic visibility through increased irrigation flow. Particularly when treating a potentially infected stone, maintenance of as low an intrarenal pressure as possible is imperative in order to prevent sepsis. Consequently, use of an access sheath, even when there is no intention of frequent entries and exits from the ureter, may increase the safety of long ureteroscopic procedures.

Dr. Margaret S. Pearle

Associate Professor of Urology

University of Texas Southwestern Med Ctr

Dallas, Texas, USA

Publication Dates

  • Publication in this collection
    26 Jan 2004
  • Date of issue
    June 2003
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