Extracorporeal shock-wave versus pneumatic ureteroscopic lithotripsy in treatment of lower ureteral calculi

Department of Urology, First Municipal People's Hospital, Guangzhou 510180, China

Asian J Androl 2002 Dec; 4: 303-305           

Keywords: ureteral calculi; lithotripsy; ureteroscopy

Abstract

Aim: To compare the efficacy and complications of extracorporeal shock-wave lithotripsy (SWL) and pneumatic ureteroscopic lithotripsy (URS) in the treatment of lower ureteral calculi. Methods: From August 1997 to June 1999, 210 patients with calculi in the distal third of the ureter were treated with SWL and the other 180 with URS. The stones were fragmented with either HB-ESWL-V lithotripter or JML-93 pneumatic lithotripter through Wolf 7.5~9.0 Fr ureteroscope. The outcome was assessed in terms of stone clearance rate, re-treatment rate and complication incidence. Results: The stone clearance rate was 78.1 % with SWL and 93.3 % with URS (P<0.05). SWL had a re-treatment rate of 11.9 %, vs 2.2 % in the URS group (P<0.05). URS caused ureteral perforation in 3.3% of patients, while it was 0 with SWL (P<0.05). The differences in the incidence of other complications such as infection and stricture between the two groups were insignificant. Conclusion: Though the selection of these two options depends on equipments available and the expertise of the operator, we recommend URS as the optimal treatment for distal ureteral calculi.

Before the 1980s, ureteral stones were managed by open ureterolithotomy [1]. Since then, extracorporeal shock-wave lithotripsy (SWL) and ureteroscopic lithotripsy (URS) have been developed and applied more and more extensively in the treatment of ureteral calculi. Currently, both are well-documented treatment options for the disease and regarded by many as the first-line management modalities [1,2]. With SWL, the whole treatment procedure is non-invasive and usually outpatient-based. Neither JJ stent nor anesthesia is required. On the other hand, URS often yields higher rate of stone clearance [3]. Thus, as to ureteral calculi, especially in the distal third of the ureter, the choice between SWL and URS has been a subject of debate for many years. The study hereby conducted was designed to investigate the relative efficacy and complications of SWL and URS.

2 Materials and methods

2.1 Patients

In the present series 390 patients with lower ureteric calculi were recruited between August 1997 and June 1999. They were randomized into two groups. Two hundred and ten patients were allocated to the SWL group with 125 males and 85 females, aged 17~72 (median 51) years. In this group, ureteral obstruction caused by lithiasis led to acute renal failure in 21 cases (10 %) and chronic renal failure in 83 (40 %). One hundred and eighty patients were allocated to the URS group with 110 males and 70 females, aged 18~75 (median 40) years. Eleven cases (6 %) were complicated with acute renal failure and 13 (7 %) with chronic renal failure caused by urinary tract obstruction. The Table 1 listed the features of the two groups. It can be seen that they were similar to each other.

2.2 Examinations

General physical examination, blood pressure, blood coagulation parameters, blood and urine routine examinations, liver and kidney function tests, midstream urine culture, B-ultrasonic scanning and X-ray examination of the urinary system were performed prior to the treatment and on day 7 and day 28 post- treatment. Complications were recorded if there were.

2.3 Treatment

For the patients of the SWL group, the HB-ESWL-V lithotripter (Haibin Medical Apparatus Co., Zhangjiang, China) was applied. After the patients were pronated or laid at a major postero-oblique position (50~85), the stones were targeted at the second focus of the ellipsoid body as shown by the cross cursor on the monitor. As a routine, each patient was given fluid irrigation intravenously and injected pethidine 100 mg. The discharge voltage was set at 8.3 to 15.0 kV and stroke times at 1500~3000 for each single episode of treatment.

For the URS group, the patients, lying at a lithotomy position, were anaesthetized epidurally. Wolf 7.5~9.0 Fr ureteroscopy (Richard Wolf GMBH, Germany) was inserted into the bladder and guided upward the affected ureter. At sight of the stone, the target was fragmented with JML-93 pneumatic lithotripter (Juxin Medical Apparatus Co., Shenzhen, China). A double J tube was then place and to be removed 3-7 days later.

3 Results

3.1 Stone clearance

On day 7 after treatment, stone clearance was noted in 112 cases (53.3 %) in the SWL group and 159 cases (88.3 %) in the URS group (P<0.05); on day 28, stone clearance was noted in 164 (78.1 %) and 168 cases (93.3 %), respectively (P<0.05).

3.2 Complications

Complications recorded 28 days after treatment were listed in Table 2.

Table 2. Complications in SWL and URS groups 28 days after treatment.

4 Discussion

Since the 1980s SWL, as an effective and non-invasive approach, has been applied extensively in the treatment of ureteral calculi [4]. No ureteral stents are needed and the patients can be treated without being hospitalized. The disadvantage of SWL was its variable stone clearance rates (53 %~97 %) and re-treatment rates (10 %~ 30 %) [5], which were in conformance with the results of the present study. URS has a higher stone clearance rate and a lower re-treatment rate and is effective in certain cases that SWL has failed. However, with URS the patients should be hospitalized and ureteral injury appears to be a potential risk in some cases.

Kim et al [6] noted that the improvement in the stone-free rate after 3 sessions of repeated SWL was minimal. However, this may increase the incidence of compli-cations. To minimize the possible injury, the stroke time and discharge voltage were controlled in this study. Generally speaking, SWL was performed less than four times for each case at an interval of 1~2 weeks with stroke time in the range of 2,500-3,000 and discharge voltage below 15 kV [7]. Pronation has been proved the optimal position for SWL to avoid the convergence of the shock wave energy to the pelvis [8]. In patients with urinary tract infection or stones larger than 15mm in diameter, antibiotics should be administered before treatment to prevent postoperative infection [9].

With different energy levels used, URS is classified into pneumatic lithotripsy (PL), ultrasonic lithotripsy (USL) and eletrohydraulic lithotripsy (EHL). Of these, PL, developed in the 1990s, was reported to be the most effective [10, 11], therefore, it was employed in this study. Compared with SWL, the advantage of ureteroscopic lithotripsy in the treatment of lower ureteral calculi is the higher rate of stone clearance, as reported previously, the efficacy of ureteroscopic treatment for lower ureteral calculi is 96 %~97 % [12]. In this group the rate was 93.3 % vs 78.1 % in the SWL group. For long-existing stones, ureteral adhesion and even polyps may be present, which wrap around the stones and impede the clearance of the calculus fragments. They are difficult to be eliminated with SWL but can be effectively removed with ureteroscopy using calculus baskets. Ureteral "stone streets" formed after SWL can also be cleared up with ureteroscopy [13]. Previous reports in China documented the incidence of complications of the lower ureteral calculi to be 2 %~8 % [14], mainly including injury to the ureter, such as perforation, laceration, hematuria and ureteral stricture, and all of these are liable to occur with unskillful practice. In our study, a JJ stent was routinely placed for 3~7 days in patients undergoing URS, as some authors have advised that the placement of JJ stent effectively prevents postoperative infection and helps drainage of urine and fragmented stones after the operation [15]. Moreover, if ureteral perforation or laceration is found, the JJ tube is needed to be placed for 4 weeks and for most of time, such management is usually successful and requires no open repair [16]. In conclusion, the authors recommend URS as the optimal treatment for distal ureteral calculi.

References

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Correspondence to: Dr Guang-Qiao ZENG, Department of Urology, First Municipal Peoples Hospital, Guangzhou 510180, China.

E-mail: zgqiao@21cn.com

Received 2002-06-24   Accepted 2002-10-05