PATIENTS AND METHODS
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- PATIENTS AND METHODS
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From January 1991 to December 2005 we retrospectively analysed the medical records of 4512 patients (2707 males and 1805 females), with a mean (sd; range) age of 41.9 (11.3; 17–71) years, who underwent 5133 ureteroscopic procedures for removal of distal ureteric calculi using different sizes of rigid and semirigid ureteroscopes under the supervision of nine staff members in our department.
The standard technique for ureteroscopy was used. Routine rigid cystoscopy was used and a flexible-tipped guidewire was passed under direct vision into the ureteric orifice and advanced under fluoroscopy beyond the stone to the renal pelvis. If passage of a guidewire was unsuccessful, then the guidewire was placed under ureteroscopic vision. The intramural ureter was then dilated using a balloon dilator, long flexible dilators or a ureteric access sheath. The ureteroscope was then passed, under direct vision, over or alongside the guidewire. The presence of a pre-existing stent or use of a small calibre scope often obviated the need for ureteric dilation. If the intramural ureter could not be adequately dilated, a double-pigtail ureteric stent was placed and ureteroscopy was delayed for 2 weeks. If an impacted stone prevented passage of a floppy tipped wire, a combination of open-ended ureteric catheters, straight and angle-tipped hydrophilic wires, angled catheters or 8–10 F coaxial dilators usually allowed the stone to be bypassed.
Once the stone is visualized a decision is made for the best means of extraction. Factors, such as size, amount of speculation, degree of impaction and condition of the distal ureter, are considered. Our methods of choice were the use of alligator forceps, wire-prong forceps or a stone basket all under direct vision. If the size of the stone precluded the use of these techniques, we disintegrate the stone using intracorporeal lithotripsy, which was also used when the stone was tightly impacted into the ureter. At our centre, pneumatic lithotripsy and laser lithotripsy (W.O.M., World of Medicine Inc., USA; U100 FREDDY® technology) were used for stone fragmentation.
At the end of the procedure, radiographic documentation using retrograde injection of contrast material into the ureter was performed and a JJ ureteric stent or external ureteric catheter was then placed. Immediate postoperative evaluation included a plain X-ray of the kidney, ureters and bladder to establish a stone-free status. In addition, an attempt was made to exclude the development of a ureteric stricture by obtaining renal ultrasound and excretory urography (IVU) at 3 months after ureteroscopy. In cases with no resolution of the preoperative hydronephrosis, a nuclear renal scan was performed to confirm functional obstruction. The mean (sd; range) follow-up was 36.8 (1.7; 3–56) months.
The patient’s characteristics including demographics, indications for calculus extraction, calculus extraction success, type of ureteroscope, mechanism of calculus extraction, intramural ureter dilation, stent placement, procedure time, hospitalization and intraoperative and postoperative complications were collected. Surgeon experience was evaluated by comparing the results of cases that were done or supervised by each of the two most experienced surgeons who performed 24% and 32% of the ureteroscopic procedures with all other surgeons performing ureteroscopy. In addition, the results of our initial 5-year experience were statistically compared with the last 10-year experience.
The unpaired t-test and chi-square test were used for statistical analyses. For bivariate and multivariate logistic regression analysis, statistical software was used to identify factors associated with ureteroscopic complications.
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- PATIENTS AND METHODS
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The patients’ characteristics and indications for endoscopic treatment of distal ureteric stones are shown in Table 1. In all, 3357 patients (74.4%) presented with primary stone disease while 1155 patients (25.6%) presented with recurrent stone disease after previous ureterolithotomy (355 patients), ureteroscopy (276 patients), extracorporeal shock wave lithotripsy (ESWL; 312 patients) or spontaneous passage of ureteric stones (212 patients).
Table 1. The patients’ characteristics
|Mean (sd; range)|
| Age, years|| 41.9 (11.3; 17–71)|
| Stone size, mm|| 9.3 (2.3; 4–22)|
|Stone side, right/left||1985/2095|
|N (%) patients with |
| Bilateral ureteric calculi||432 (9.6)|
| Multiple ureteric stones||556 (12.3)|
| Ureteric Steinstrasse||173 (3.8)|
| Associated Bilharzial ureter||866 (19.2)|
| Preoperative stents ||852 (18.9)|
|Presentation, N (%)|
| Intractable colic or pain||2250 (49.9)|
| Upper tract obstruction||442 (9.8)|
| Persistent haematuria||136 (3.0)|
| Recurrent infection||194 (4.3)|
| Intolerable bladder irritation|| 113 (2.5)|
| Lack of progression||641 (14.2)|
| Combination||736 (16.3)|
In all, 4512 patients underwent 5133 transurethral ureteroscopic stone manipulations and the success rate based on the complete removal of calculi was 94.6% (4856 of 5133 procedures). The successful ureteroscopic manipulations included 2883 procedures (59.37%) of simple stone extraction with grasping forceps or basket stone manipulation and 1973 procedures (40.63%) of pneumatic lithotripsy with the Lithoclast (1136 procedures) or laser lithotripsy with the FREDDY laser (837 procedures) followed or not by removal of the fragments with the basket or grasping forceps. There were 621 patients who underwent 1242 ureteroscopic procedures; 432 patients had two separate calculus extraction within 8 months, while 189 patients underwent 378 procedures due to failure to extract the stone the first time. The reasons for failure of stone removal were lower end Bilharzial ureteric stricture (28 cases), severe ureteric oedema with inability to introduce a guidewire (eight cases) or the occurrence of intraoperative complications that necessitated postponing the procedure or shifting to other therapeutic methods (241 cases).
Operative and postoperative data are shown in Table 2. General anaesthesia was used in 64.8% of the procedures. The ureteric orifice was dilated in 59.5%. Direct introduction of the ureteroscope into the ureter without dilation was performed in 24.9% due to the use of small size semirigid endoscope (in 235 procedures) or the ureter was stented preoperatively (1041 procedures).
Table 2. Operative and postoperative data
|Total no. pts./total no. procedures||4512/5133|
|Anaesthesia, n (%)|
| General||3326 (64.8)|
| Spinal||1807 (35.2)|
|Ureteric dilation, n (%)|
| Ureteric balloon||2644 (51.5)|
| Flexible dilators|| 411 (8)|
| Ureteric access sheath||802 (15.6)|
| None||1276 (24.9)|
|Mean (sd; range) operative time, min||43.6 (15.0;25–120)|
|N (%) |
| Intraoperative complications||340 (6.6)|
| Postoperative complications||509 (9.9)|
| Repeat treatment rate ||189 (3.7)|
| Stone-free rate ||4856/5133 (94.6)|
|Mean (sd; range) |
| Hospital stay, days|| 1.7 (1.6; 0–7)|
| Postoperative stent, days|| 9.5 (1.9; 2–28)|
| Follow-up, months||36.8 (1.7; 3–56)|
The mean (sd; range) operative duration was 43.6 (15.0; 25–120) min (The operative durations for cases that underwent open exploration for extravasation or ureteric reimplantation due to avulsion were not included in the mean operative time). The mean (sd; range) postoperative hospital stay was 1.7 (1.6; 0–7) days.
The overall intraoperative and postoperative complications are shown in Table 3. Upward migration of the stone occurred during 33 procedures. In 25, the procedure was postponed for 2–3 days after insertion of ureteric catheter and a second ureteroscopy was performed with successful stone extraction from the middle third ureter. In the remaining cases, successful ESWL was performed for migrated stone up to the upper ureter and renal pelvis. Ureteric bleeding and mucosal laceration (in 120 procedures) were minor complications that did not interfere with successful stone extraction except in 46 cases in which a ureteric stent was placed and the procedure was postponed because the bleeding prevented proper visibility.
Table 3. Complications during and after ureteroscopy
|Complications||Total no. of complications in 5133 procedures, n (%)||Complications in 1195 procedures from 1991 to 1995 (group 1), n (%)||Complications in 3938 procedures from 1996 to 2005 (group 2), n (%)||P|
| Stone upward migration|| 33 (0.64)|| 18 (1.5)|| 15 (0.4)|| |
| Ureteric bleeding|| 63 (1.23)|| 26 (2.2)|| 37 (0.9)|| |
| Mucosal injury|| 57 (1.11)|| 25 (2.1)|| 32 (0.8)|| |
| False passage|| 86 (1.68)|| 38 (3.2)|| 48 (1.2)|| |
| Ureteric perforation|| 58 (1.13)|| 39 (3.3)|| 19 (0.5)|| |
| Ureteric avulsion|| 18 (0.35)|| 15 (1.3)|| 3 (0.1)|| |
| Residual stones|| 25 (0.49)|| 19 (1.6)|| 6 (0.2)|| |
|Total||340 (6.62)||180 (15.1)||160 (4.1)||<0.001|
| Persistent pain||164 (3.2)|| 57 (4.8)||107 (2.7)|| |
| Persistent fever|| 77 (1.5)|| 23 (1.9)|| 54 (1.4)|| |
| Haematuria|| 113 (2.2)|| 44 (3.7)|| 69 (1.8)|| |
| Ileus >1 day|| 22 (0.43)|| 9 (0.8)|| 13 (0.3)|| |
| UTI|| 121 (2.36)|| 51 (4.3)|| 70 (1.8)|| |
| Ureteric stricture|| 12 (0.23)|| 8 (0.7)|| 4 (0.1)|| |
|Total||509 (9.92)||192 (16.1)||317 (8)||<0.001|
Asymptomatic perforation or false passage of the ureter was seen during 86 procedures (1.68%). These perforations occurred during guidewire placement (50 procedures), ureteroscope placement (16 procedures), or during stone and instrument manipulation (20 procedures). Perforation or false passage did not interfere with the stone extraction in 61 cases, while in the remaining 25 cases perforations were managed by ureteric stenting for 1–4 weeks and a second ureteroscopy was successfully performed later. Perforation of the ureter with evidence of urinary extravasation occurred in another 58 procedures (1.13%) during ureteroscope insertion (21 patients), stone extraction by stone basket (27 patients) and during lithotripsy (10 patients). Of these patients, 32 were treated with an indwelling ureteric stent followed by a second ureteroscopy and successful stone extraction 3–4 weeks later. Nine patients were managed by percutaneous nephrostomy tube drainage because of an inability to insert a retrograde ureteric stent, while 17 patients underwent open drainage because of the large amount of extravasation associated with pain and fever encountered after ureteroscopy. In two of these patients with ureteric perforation, the stones migrated outside the ureter through the perforation site and they were left in the retroperitoneum. There have been no sequelae in one patient after 8 months while the other patient developed lower third ureteric stricture 6 months after ureteroscopy, which was managed successfully by open ureteric reimplantation. Of these 58 cases in which ureteric perforation occurred, the calculus was impacted in 36. Ureteric avulsion occurred in another 18 patients (0.35%) during basket stone extraction of intact stone or big fragments and they underwent immediate ureteroneocystostomy.
At the end of the procedure, a double-pigtail ureteric stent was placed in the ureter after 3326 of the ureteroscopic procedures (64.8%). After another uncomplicated 557 procedures (10.85%) with short manipulation times (<30 min), a 5 or 6 F ureteric catheter was positioned in the renal pelvis and tied to a Foley catheter. The Foley and ureteric catheters were removed within 1–2 days after ureteroscopy. In 235 (4.58%) procedures in which smaller size semirigid endoscopes were used without dilation of the intramural ureter and the stones were extracted easily without any complications, the ureters were left unstented and no significant complications were encountered in these patients. In patients who presented with a preoperative indwelling ureteric stent (852 referred from other centres and 189 failed first ureteroscopic stone extraction), it was unnecessary to place another stent after the procedure except in 232 patients who had a large stone burden or a prolonged procedure. The mean (sd; range) postoperative stent period was 9.5 (1.9; 2–28) days. The size and type of ureteroscopes are shown in Table 4 and Fig. 1.
Table 4. Comparison of ureteroscopy results of group 1 (initial 5-year experience) for ureteroscopic extraction of lower ureteric calculi with group 2 (the last 10-years experience)
|Variable||Group 1 (1991–1995), 1195 procedures||Group 2 (1996–2005) 3938 procedures ||P|
|No. Patients/procedures|| 970/1195||3542/3938|| 0.03|
|Mean (sd; range)|
| Stone size, mm|| 9.4 (2.3; 5–20)|| 10.9 (3; 4–22)||<0.001|
| Operative duration, min|| 75 (2.9; 40–120)|| 36.5 (12.5; 25–55)||<0.001|
| Procedures requiring ureteric dilation|| 843 (70.5)||2212 (56.2)|| 0.001|
| Ureteric access sheath used||None|| 802 (20.4)|| |
| Types of ureteroscopes|
| 6.9 F|| 0|| 915 (23.2)|| |
| 7.2 F|| 0||1476 (37.5)|| |
| 9 F|| 367 (30.7)||1024 (26)|| |
| 9.5 F|| 390 (32.6)|| 302 (7.7)|| |
| 11.5 F|| 402 (33.6)|| 69 (1.8)|| |
| Multiple|| 36 (3)|| 152 (3.9)|| |
| Significant intraoperative complications|
| Ureteric perforation|| 39 (3.3)|| 19 (0.5)|| 0.05|
| Ureteric avulsion|| 15 (1.3)|| 3 (0.1)|| 0.05|
| Significant postoperative complications|| || || |
| Ureteric stricture|| 8 (0.7)|| 4 (0.1)|| 0.007|
| Stone-free rate||1024 (85.7)||3831 (97.3)||<0.001|
|Mean (sd; range) hospital stay, days|| 2.5 (1.6; 2–7)|| 0.5 (1.2; 0–3)||<0.001|
Follow-up imaging with renal ultrasound, excretory urography and/or nuclear renal scan at least 3 months after ureteroscopy was available in 3215 patients (71.3%) and showed evidence of delayed stricture formation in 12 patients (0.23%) at a mean (range) of 7.6 (1–14) months after stone extraction. All these patients with ureteric stricture had impacted ureteric stones and six of them had insignificant or significant ureteric perforations at the time of the procedure. Six of the 12 patients with strictures were symptomatic, while in six who were asymptomatic ureteric stricture was identified by radiological studies. Eight strictures were managed successfully in the short term by balloon dilation and placement of a double-pigtail stent, while four patients underwent successful ureteroneocystostomy.
Table 4 shows a comparison of ureteroscopy results of the initial 5-year experience (1991–1995) with 1195 ureteroscopic procedures (23.28%) for 970 patients (group 1) and the last 10-year experience (1996–2005) with 3938 ureteroscopic procedures of the same technique (76.72%) for 3542 patients (group 2). The overall ureteroscopic success increased significantly from 85.7% to 97.3% (P < 0.001), the mean (sd) procedure time significantly decreased from 75 (42.9) min to 36.5 (12.5) min (P < 0.001) and the mean hospital stay decreased from 2.5 (1.6) days to 0.5 (1.2) days for group 1 to group 2, respectively. The overall intraoperative complication rate decreased from 15.1% to 4.1% (P < 0.001) and the postoperative complication rate decreased from 16.1% to 8.0% (P < 0.001). Significant intraoperative complications, defined as significant ureteric perforation and avulsions occurred in 22 patients (0.6%) in group 2, with 19 perforations (0.5%) and three avulsions (0.1%) compared with 54 patients (4.5%) in group 1, with 39 perforations (3.3%) and 15 avulsions (1.3%). Ureteric stricture occurred in four patients (0.1%) in group 2 compared with eight patients (0.7%) in group 1.
Bivariate analysis (Table 5) showed a significant association of the major intraoperative complications with increased operative duration (P < 0.001), large stone size (P < 0.01), presence of stone impaction (P < 0.01) and surgeon experience (P < 0.03). In addition, there was a significant association of the major complications with the type of ureteroscope used (P < 0.02). Multivariate logistic regression models showed that the major complications remained highly associated with operative duration, stone size, stone impaction, type of ureteroscope and surgeon experience when controlling for the other factors (P < 0.001). In the present series 17 of the 58 perforations occurred while using the 11.5 F ureteroscope. In addition, none of the patients with intraoperative ureteric avulsion or postoperative ureteric stricture had had preoperative ureteric stents.
Table 5. Analysis of patients with significant complications
|Variable||Ureteric complications||Successful procedures with no significant complications|
|Number of patients||58|| 18||12||4856|
|Mean (range) age, years||49 (29–65)|| 46 (33–62)||43 (28–66)|| 41.9 (17–71)|
|Mean (sd) stone size, mm||11.5 (2)|| 10.5 (3)||11 (2)|| 9.3 (2.3)|
|Impacted stones, n (%)||36 (62)|| 10 (56)||12|| 594 (12)|
|Mean (sd) operative duration, min||95 (34)||105 (26)||85 (16)|| 42 (15.0)|
|No. with preoperative stents|| 3|| 0|| 0||1038|
|No. with ureteroscope|
| 6.9 F|| 2|| 0|| 1|| 906|
| 7.2 F||16|| 1|| 3||1430|
| 9 F||12|| 6|| 2||1316|
| 9.5 F||11|| 4|| 2|| 621|
| 11.5 F||17|| 7|| 5|| 410|
| Multiple||–||–||–|| 173|
We analysed the ureteroscopy database on nine staff members with a range of ureteroscopy experience; there was an association of surgeon experience with stone-free rate and the likelihood of intraoperative ureteric injuries (residual stones, mucosal injury, false passage, perforation, and avulsion). Comparing the results of cases which were done or supervised by each of the two most experienced surgeons (who performed 24% and 32% of the ureteroscopy procedures and had an average of 82.5 and 104.3 procedure of ureteroscopic stone removal yearly, range 32–160) with the remaining surgeons who had an average of 22.4 procedures yearly (range 4–48), showed that increased surgeon experience was significantly associated with a decreased rate of intraoperative complications from 9.4% to 3.1% (P < 0.03) and increased stone-free rate from 82% to 98% (P < 0.001).
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Despite the fact that ureteroscopy is more invasive but less expensive than ESWL in managing distal ureteric stones, most authors would consider either option as a reasonable alternative [1,5–7]. Ureteroscopy is usually favoured when stones are larger than 10 mm, are known to be cystine, appear radiolucent or possibly occur in women of childbearing age [8–10]. Review of published series from the last decade on the treatment of ureteric calculi with ureteroscopy, using a variety of ureteroscopes and intracorporeal lithotripsy devices, revealed success rates of 86–100%.
In the present series, the overall stone-free rate for ureteroscopic extraction of lower third ureteric calculi was 94.6% during the 15-year period of study, which rose to 97.3% during the last 10 years of the study. Actually, on reviewing our last 200 cases of ureteroscopic stone extraction, the success rate was 100%; this is attributable to the learning curve and accumulation of experience with ureteroscopy, the availability of small rigid and semirigid ureteroscopes, and the Lithoclast and laser lithotripters that are highly efficient and economical instruments for stone fragmentation. The present results are compatible with those reported by others [4,11–15].
In the present study, dilation of the ureteric orifice and intramural ureter was performed in 59.5% of cases, ureteric access sheath was used in 15.6% and no dilation was required for patients who have previously received a stent. In our experience, ureteric dilation allows for more rapid, less forceful access, which is important if multiple passes of one or multiple ureteroscopes are necessary. Also, dilation allows for easier extraction of larger or irregular stones. Convincing evidence for the safety of orifice dilation was reported by Garvin and Clayman , who reported no clinical significant long-term sequelae from routine 24 F ureteric orifice dilation. The incidence of strictures is decreased by the routine placement of postoperative double-pigtail ureteric stents. Other studies reported successful introduction of rigid and flexible ureteroscopes without dilation [17,18]. In the present study, 235 (4.58%) patients in whom we used small semirigid ureteroscopes, dilation of the ureteral orifice was not required and the stones were extracted easily with no significant complications and the ureters were left unstented.
In the present study, 189 patients (3.7%) underwent secondary ureteroscopy after an unsuccessful ureteroscopy. Factors contributing to the unsuccessful attempts included lower end Bilharzial ureteric stricture or oedema, upward migration of the stone, ureteric bleeding, mucosal injury, false passage, ureteric perforation, and/or failed intracorporeal lithotripsy. Not only does the stent after a previous failed attempt provide urinary drainage but subsequent instrumentation may be made easier due to passive dilation [19,20]. We anticipate that many clinicians would wait a few weeks to allow any inflammation from the first attempt to resolve even when a patient has been successfully stented and remains clinically well.
Stents have been a routine part of the postoperative care after ureteroscopy until the need was questioned by recent reports showing that stenting was not always necessary after the use of small ureteroscopes and recent intracorporeal lithotripsy devices for distal ureteric calculi [21,22]. Most of the procedures in the present study were completed by placing either a ureteric stent (64.8%) or ureteric catheter (10.85%); however, in 4.58% procedures in which smaller semirigid endoscopes were used with no dilation of the intramural ureter, the stones were extracted easily without any complications and the ureters were left unstented. The insertion of a ureteric catheter at the end of the procedure was performed when the manipulation time was <30 min. Otherwise, a JJ catheter was placed if the manipulation time was >30 min or if a ureteric injury was suspected. In those patients in whom a ureteric catheter was inserted instead of ureteric stent, the procedure of ureteroscopic stone extraction was uncomplicated, straightforward and as we still have the concern of leaving the ureter unstented after ureteroscopy to avoid partial urinary obstruction and flank pain due to mucosal oedema. For this reason, we insert an external ureteric catheter for 48 h (maximum) to avoid a second cystoscopy to remove an indwelling stent, taking in to consideration the overall costs. This concept is in agreement with Djaladat et al. who reported in a randomized controlled trial that short-term external ureteric catheterization in uncomplicated ureteroscopy and lithotripsy has a role in reducing early postoperative morbidities and may also decrease pain and colic after discharge.
While ureteroscopy has proved to be an effective therapy in the treatment of ureteric calculi, it has greater potential for complications. Early series of ureteroscopy highlighted the potential complications that may arise. In a review of the early Mayo Clinic experience , complications were reported in 20% of patients, including fever, failure to remove the stone and ureteric injury. Ureteric strictures were noted in 1.4% of patients. In 1987, Kramolowsky  reported ureteric perforations in 17% of patients undergoing ureteroscopy due to the use of sequential dilators on the ureteric orifice or larger rigid ureteroscopes (11.5 F or 13 F). Most of the patients were treated conservatively with a subsequent stricture rate of 35%. Similarly, Lytton et al. reported in 1987 ureteric perforation in 14 of 128 patients (18%) following which 12 were treated nonoperatively with a stent. In the current endourological era, with wide access to newer, smaller rigid and flexible instruments and use of small calibre intracorporeal lithotripsy devices, the complication rate and morbidity of ureteroscopy have been significantly reduced compared with earlier series. Currently, the rates for ureteric perforation and stricture are 2–4% and 0–2%, respectively [11,27–30]. Stoller and Wolf  in a comprehensive review of intraoperative ureteric injuries reported in the literature from 1984 to 1992, identified 314 ureteric perforations that occurred during 5117 procedures (6.1%) and complete ureteric avulsion in an additional 17 (0.3%). Harmon et al. reviewed the change in the complication rate with time at a single institution. They reported a decrease in overall complications from 20% to 12% in a 10-year interval. Significant complications, including ureteric perforation, avulsion and stricture, also decreased from 6.6% to 1.5% in the same interval.
Comparing the ureteroscopic procedures completed ibetween 1991 to 1995 (group 1) and 1996 to 2005 (group 2) showed significant improvements in success rates with decreased morbidity; the success of treating stones increased from 85.7% to 97.3%. This experience reflects the improvement in hospital stay and the move toward outpatient treatment (mean 2.5 days in group 1 and 0.5 days in group 2). Smaller rigid scopes were used by 1997 with only 1.8% of cases treated with an 11.5 F ureteroscope in group 2 patients vs 33.6% treated with a larger instrument in group 1. In the present series, the overall intraoperative and postoperative complication rates were 16.5% with a significant complication rate of 1.7%, included ureteric perforation (1.13%), ureteric avulsion (0.35%) and ureteric stricture (0.23%), which is in agreement with most recent published large series [27–31]. The overall intraoperative complication rate decreased from 15.1% to 4.1% (P < 0.001) and the postoperative complication rate decreased from 16.1% to 8% (P < 0.001) for group 1 to group 2, respectively. Significant intraoperative complications occurred in 22 patients (0.6%) in group 2 compared to 54 patients (4.5%) in group 1. Ureteric stricture occurred in four patients (0.1%) in group 2 compared with eight patients (0.7%) in group 1.
Notably, all 12 ureteric strictures in the present series had had impacted ureteric stones and six of them had insignificant or significant ureteric perforations at the time of the procedure. This is similar to the results of the retrospective study reported by Roberts et al. on 21 patients with impacted ureteric stones for >2 months. These patients underwent endoscopic stone extraction and at a mean follow-up of 7 months, ureteric strictures developed in five patients (24%) at the previous stone site and four of the five strictures occurred in patients who had had iatrogenic ureteric perforation during previous unsuccessful attempts at stone removal.
Analysis of the results of cases which were performed by the most experienced surgeons in present study, showed that increased surgeon experience was significantly associated with a decreased rate of intraoperative complications from 9.4% to 3.1% (P < 0.03) and increased stone-free rate from 82% to 98% (P < 0.001), which is similar to the analysis of experience at 28 medical centres reported by Weinberg et al., who reported a decrease from 4.9% to 3.3% in the number of intraoperative injuries with increased surgeon experience.
In the present study, bivariate analysis showed a significant association of the major intraoperative complications with increased operative time, large stone size, presence of stone impaction and decreased surgeon experience. In addition, there was a significant association of the major complications with the type of ureteroscope used (i.e. increase complications rate with larger ureteroscopes). In multivariate logistic regression models, the major complications remained highly associated with operative duration, stone size, stone impaction, surgeon experience and type of ureteroscope, when controlling for the other factors. In the present series 17 of the 58 perforations occurred while using the 11.5 F ureteroscope. In addition, none of the patients with intraoperative ureteric avulsion or postoperative ureteric stricture had had preoperative ureteric stents.
Ureteroscopic stone extraction requires considerable caution and should not be continued if the stone cannot be visualized at all times during withdrawal down the ureter. Undue force should never be used. Intraoperative considerations included the use of a C-arm fluoroscopic unit, establishing security with the placement of safety guidewire and adequate balloon dilation of the ureteric orifice when using a 9.5 F or larger ureteroscope. Having various catheters and guidewires available along with small semirigid and rigid endoscopes increases the probability of rendering the patient stone-free and decreases the chance of further trauma to the ureter. As is the case with all ureteroscopy the virtues of working patiently and having knowledgeable nursing support cannot be overstressed.
In conclusion, following training and accumulation of experience with ureteroscopy a higher success rate with fewer complications was evident in the present large series. The use of a wide array of currently available ureteroscopes, baskets, guidewires, catheters, and endoscopic lithotripters is also responsible for the increased success rate. These advances have enabled urologists to treat complex ureteric stones successfully and as a single, definitive procedure.