Retrograde Ureteroscopic Treatment for Upper Ureteral Stones: A 5-Year Retrospective Study

Introduction

T he advents of extracorporeal and intracorporeal stone fragmentation have significantly changed the pattern of upper ureteral stone management. Because these less-invasive treatments have a high success rate, with a significant number of patients being stone-free postoperatively, open surgery for upper ureteral stones is reserved for only the most complex stones and those with altered ureter anatomy. ¹ Although extracorporeal shockwave lithotripsy (SWL) is still the least invasive treatment modality for upper ureteral stones, several disadvantages affect its performance, such as high re-treatment rate, long treatment time, restriction by the stone size, and a need for special positioning of many patients. ² Percutaneous nephrolithotomy (PCNL) as an intracorporeal technique for upper ureteral stones is considered mainly in patients with a large stone burden. ³

Ureteroscopic lithotripsy was first introduced for distal ureteral stones and has achieved a high success rate. ^4,5 The development of small caliber semirigid ureteroscopes and efficient lithotripters has made it possible to manage upper ureteral stones. ^6,7 In this study, we present our 5-year experience with 372 patients who underwent upper ureteral stone removal using a semirigid ureteroscope. In addition, we compared the treatment outcomes between pneumatic and holmium laser lithotripsy for upper ureteral stones.

Patients and Methods

We retrospectively analyzed the medical records of 372 patients (219 men and 153 women), with a mean age of 42.7 ± 11.5 years (range 17–75 y), who underwent 384 ureteroscopic procedures for removal of upper ureteral stones under the supervision of four experienced urologists in our department between January 2003 and December 2007.

The procedures were performed on an inpatient basis using a 8/9.8F Wolf semirigid ureteroscope under epidural anesthesia in 310 cases (310/372, 83.3%) and general anesthesia in 62 cases (62/372, 16.7%). Patients were placed in the standard lithotomy position. The ureteroscope was inserted into the bladder through the urethra under visual monitoring, and a 3F or 4F ureteral catheter was placed into the ureteral orifice through the working channel to guide the insertion of the ureteroscope. If the passage of the ureteral orifice was difficult, the ureteroscope was withdrawn from the bladder with the ureteral catheter indwelling. The ureteroscope was placed again, and another 3F or 4F ureteral catheter was inserted. Under the guidance of the second ureteral catheter, the ureteroscope was slid into the ureter between the two ureteral catheters. The first ureteral catheter was removed after the ureteroscope had passed the orifice. Intermittent low-pressure irrigation was used to obtain a clear operative visual field.

Once the stone was visualized, the patient was positioned with the side bearing the stone elevated laterally by 30 degrees. Furosemide 20 mg was administered through venous access. A Swiss pneumatic Lithoclast with 0.8 mm and 1.0 mm probes or a holmium:yttrium-aluminum-garnet laser (80 watts) was used. The laser fiber used was 550 μm, with energy of 0.8 to 1.5 joules and a frequency of 12 to 20 Hz. Lithotripsy was terminated when stone fragments were small enough to expect spontaneous evacuation.

At the end of the procedure, a 5F Double-J stent with both ends open was inserted into the ureter through a 0.038 inch guidewire under monitoring and was left indwelling for 2 to 4 weeks. Postoperative imaging including ultrasonography and plain radiography of the kidneys, ureters, and bladder were conducted to verify stone passage and monitor the recovery from hydronephrosis. Follow-up radiography was performed to look for evidence of residual stones. If the patient was clear of stones, the Double-J stent was removed under local anesthesia on an outpatient basis. In addition, an attempt was made to exclude the development of ureteral stricture by renal ultrasonography at 3 months after ureteroscopy, and to confirm by excretory urography and/or nuclear renal scan. The mean follow-up was 9.3 ± 4.5 months (range 4–12 mos).

Statistical analysis was performed by using the chi-square test for qualitative variables and the Student t test for quantitative variables. The level of significance was defined as P < 0.05.

Results

Patient characteristics and stone-associated data are shown in Table 1. A total of 12 patients with bilateral upper ureteral stones, who were treated by bilateral retrograde ureteroscopic lithotripsy on the same occasion, were included in this study. In all, 372 patients underwent 384 procedures. Of the 384 procedures, 291 (75.8%) managed primary stone disease while 93 (24.2%) managed recurrent stone disease after previous SWL (68 procedures), ureteroscopy (13 procedures), or ureterolithotomy (12 procedures). The total success rate based on the initial complete removal of stones was 90.4% (347 of 384 procedures). The successful procedures included 132 (132 of 159 procedures, 83.0%) in group 1 and 215 (215 of 225 procedures, 95.6%) in group 2. The reasons for failure of stone removal included severe edema impaction at the site of stone (1 case in group 2), sharply angulated ureter obstruction (1 case in group 1 and 1 case in group 2), and the occurrence of intraoperative complications that necessitated shifting to other therapeutic methods (26 cases in group 1 and 8 cases in group 2).

Operative and postoperative data are shown in Table 2. The mean operative duration was 41.2 ± 10.7 minutes (range 29–67 min). The failed procedures were not included in the mean operative time. The mean postoperative hospital stay was 2.7 ± 0.9 days (range 1–5 d). The overall intraoperative complication and postoperative complication rates were 14.6% and 3.9%, respectively. The rates of major complications that were acceptable in this series included intraoperative ureteral perforation and avulsion and postoperative ureteral stricture. Perforation was recorded in three (0.9%) procedures, all of which occurred during stone manipulation. One of the three was asymptomatic perforation in group 1 and did not interfere with the stone extraction; another two in group 2 underwent open surgery to retrieve the stone and drain the extravasation. Ureteral avulsion occurred in one (0.3%) patient in group 1 during forceps extraction of big fragments, and he underwent immediate ureteroneocystostomy. Follow-up ultrasonography at 3 months after ureteroscopy was available in 270 (72.6%) patients to screen for delayed stricture formation; 36 patients in whom there was suspicion underwent further examination with excretory urography and/or nuclear renal scan, and stricture was confirmed in one patient. The stricture was managed by balloon dilation and the insertion of an 8F Double-J stent for 1 month.

Upward migration of the stone was the most common intraoperative complication that occurred during 29 (7.6%) procedures, which were managed by insertion of Double-J stents and SWL after 2 weeks. Mucosal lesion (in five procedures, 1.3%) and uretera; bleeding (in 10 procedures, 2.6%) were minor intraoperative complications that did not influence with successful stone extraction, with the exception of two cases in group 1 where the bleeding prevented proper visibility, so open surgery was performed. False passage of the ureter was seen during eight (2.1%) procedures, which did not interfere with the stone extraction but was treated with a Double-J stent indwelling for 4 weeks. Of the eight procedures, three were in group 1 that occurred during ureteral catheter placement (three procedures), and the other five were in group 2 that happened during ureteral catheter placement (three procedures), ureteroscope placement (one procedure) or laser fiber placement (one procedure). Fever and macroscopic hematuria were minor postoperative complications that would improve with time, except in two cases in whom recovery did not occur until the Double-J stent was removed.

The comparison results between group 1 and group 2 are shown in Table 1 and Table 2. The two groups had comparable demographic data and stone-associated data (Table 1). The average hospital stay in group 1 was 2.7 ± 1.2 days (range 1–5 d) and in group 2 was 2.6 ± 0.6 days (range 1–5 d) (P > 0.05). Mean operative time was 43.3 ± 11.1 minutes (range 35–67 min) for group 2, which was significantly longer than that for group 1, which was 38.7 ± 9.1 minutes (range 29–56 min) (P < 0.05). With respect to complications, the significantly higher intraoperative complications of group 1 (22.0% vs 9.3%, P < 0.001) coincide with a significantly lower stone-free rate when compared with group 2 (83.0% vs 95.6%, P < 0.001). Postoperative complications occurred in six (3.8%) patients in group 1 compared with nine (4.0%) in group 2 (P > 0.05).

Discussion

The current strategy for management of upper ureteral stones in China include medication with Chinese traditional medicine, SWL, ureteroscopy, and PCNL using different intracorporeal lithotripters, laparoscopic and open ureterolithotomy. Although all of them are effective management options for removal of upper ureteral stones, each of them is associated with its own scope and complications. ^{1 –3,6 –11} Previous studies have demonstrated that, compared with other options, ureteroscopy may achieve excellent results for upper ureteral stones, and the immediate, high success rate with acceptable complications made some researchers consider this procedure as the first choice for SWL powerless stone in the upper ureter. ^6,7,10 A review of published series from the last 5 years on the mangement of upper ureteral stones with retrograde ureteroscopy, using a variety of ureteroscopes and intracorporeal lithotriptors, revealed a stone-free rate of 70.3% to 97.1%. ^{3,6,7,10 –14}

In our series, the overall stone-free rate was 90.4%, which was compatible with those reported recently. The stone-free rate was significantly different between the pneumatic lithotripsy group and the laser lithotripsy group, which were 83.0% and 95.6%, respectively. The main factor contributing to unsuccessful procedures was stone upward migration to the renal pelvis beyond the reach of the ureteroscope. The stone upward migration occurred during 23 (14.5%) procedures in the pneumatic lithotripsy group, which was significantly more than that in the laser lithotripsy group (6, 3.1%). Moreover, in the pneumatic lithotripsy group, 19 of the 23 (82.6%) upward migrations occurred during stone fragmentation while only 2 (33.3%) procedures happened during that time in the laser lithotripsy group.

The different rate of stone upward migration was mainly associated with the mechanism of the two lithotriptors. Holmium laser lithotripsy occurs primarily through a photothermal mechanism that causes stone burst and vaporization, while pneumatic lithotripsy, achieved by clean pressurized air, acts as an energy source to fire the projectile onto a metal rod that is in contact with the stone. ^15,16 It is easy to understand that the photothermal mechanism is more efficient in decreasing stone upward migration when compared with the mechanical shock mechanism.

Stone upward migration is also associated with high-pressure irrigation. Irrigation is critical to maintain a clear endoscopic visual field by displacing blood, stone fragments, and cellular debris and by distending the lumen under investigation. ¹⁷ At the same time, however, irrigation flow and pressure can push the stone away during dilation of the ureter orifice, the process of ureteroscope insertion, and during stone fragmentation. In our series, we used two ureteral catheters as a guidewire for ureteroscope insertion, which was effective to avoid high-pressure irrigation for dilation of the ureter orifice. Inserting the ureteroscope between the two ureteral catheters created an extrusion force to expand the ureter orifice, which made it easier to insert the ureteroscope.

During the procedures, intermittent low-pressure irrigation was used as a suitable means to create a clear visual field with the added benefit of avoiding stone upward migration. In the case of intraoperative complications, however, it was necessary to increase the pressure to maintain clear visibility and that resulted in stone upward migration during eight procedures (four vs four between group 1 and group 2). Moreover, to prevent upward migration during stone fragmentation, we administrated furosemide 20 mg to improve antegrade urine flow, which helped to maintain a clear visual field and wash down the stone fragments. In addition, positioning the patient with the side bearing the stone elevated laterally by 30 degrees further prevented stone upward migration by gravitational force. ¹³ Patient repositioning, however, should be performed after the ureteroscope has been used to locate the stone, because that position may cause ureter distortion, which would impede the insertion of the ureteroscope.

In our series, a 5F Double-J stent was indwelling mainly to avoid sudden ureteral obstruction by stone fragments, blood clots, or mucosal swelling. A silk thread was sutured distally of the stents (the silk left to protrude out of the urethra) in 137 patients whose stones were extracted easily without any complications. In those patients, the Double-J stent was left indwelling for 48 hours (maximum) and was removed by pulling the silk thread to avoid a second cystoscopy. This concept is similar to that used by Djaladat and associates, ¹⁸ who used a short-term external ureteral catheter after uncomplicated ureteroscopy to avoid a second cystoscopy. This reduced early postoperative morbidities and might also decrease pain and colic after discharge.

Although recent reports argue that not using a stent does not pose a higher risk of complications and that fewer postoperative symptoms are recorded vs those with a stent, ^{19 –21} we decided to use a short-term indwelling stent. We thought that this was a suitable choice because it reduced the risk of having to perform a second ureteroscopy in the case of an obstruction. Furthermore, in our series, no obvious postoperative morbidities were caused by the short-term indwelling stent.

As surgeons gain in experience and develop finesse in performing the procedure together with technologic improvements, the rate of complications during ureteroscopy is significantly reduced. Harmon and colleagues ²² compared a patient cohort in their institute from the early 1980s with a cohort from 1992; a decrease in overall and significant complications was seen from 20% to 12% and 6.6% to 1.5%, respectively. Geavlete and coworkers ²³ reviewed 2735 retrograde semirigid ureteroscope procedures from 1994 to 2005, identifying that 76% of the complications occurred in the first 5 years and that major complications such as ureteral perforation (0.65%), ureteral avulsions (0.11%), and ureteral stricture (0.1%) have decreased over time. Elashry and colleagues ²⁴ showed that over a period of 10 years, the rate of intraoperative complications decreased from 9.4% to 3.1% and the stone-free rate increased from 82% to 98%.

In the present study, false passage, small mucosal lesions, ureteral bleeding, postoperative fever, macroscopic hematuria, and stone migration were the most prevalent complications. The overall intraoperative and postoperative complication rates were 18.5% with a significant complication rate of 1.5%, including ureteral perforation (0.9%), ureteral avulsion (0.3%), and ureteral stricture (0.3%). If we excluded the inherent problem of the upper ureteral stone migration to the renal pelvis, the data in our series were in agreement with large cohorts in previously published series.

Comparing complications between the pneumatic lithotripsy group and the laser lithotripsy group showed significantly higher intraoperative complications (22.0% vs 9.3%) with a significantly lower stone-free rate (83.0% vs 95.6%). The incidence of intraoperative and postoperative complications between the two groups, however, was not statistically significant, except the rate of stone upward migration. Although the mechanism of the lithotriptor was the major cause of stone upward migration, we could not neglect some of the intraoperative complications that potentially lead to stone upward migration and in some cases necessitate additional procedures.

Conclusion

Retrograde ureteroscopy is a safe and effective method for managing upper ureteral stones. Our study confirms that holmium laser lithotripsy as a suitable lithotriptor has the capability to decrease stone upward migration and to achieve a high success rate. In addition, for upper ureteral stones, the high stone-free rate was also associated with the experience and finesse of the surgeon to prevent the stones migrating upward.