Original Article

Utility of the lithoclast in the treatment of upper, middle and lower ureteric calculi

M.S. Akhtar F.K. Akhtar
Department of Urology, Post Graduate Medical Institute, Lahore General Hospital, Lahore, Pakistan

Correspondence to: M.S. Akhtar, 132 Tipu Block, New Garden Town, Lahore, Pakistan

Introduction Patients and methods Results

Discussion Conclusion References

Keywords: Ureteric calculi, ureteroscopy, lithoclast, intracorporeal lithotripsy Surg J R Coll Surg Edinb Irel., 1 June 2003 144-148

Objective: The aim of this study was to evaluate the utility and efficacy of lithoclast in the treatment of upper, middle and lower ureteric calculi. Patients and Methods: Over a period of 6 1/2 years, we have treated 529 ureteric stones which failed to pass spontaneously within a 2-week period. Patients were evaluated for number, site, size and laterality of stones. Patients with ureteroscopy failure were excluded from the study. Once the stone(s) was (were) localised with the ureteroscope, it (they) was (were) treated with the Swiss lithoclast. Results: Complete fragmentation was achieved in 99% of cases with lower, 97% with mid and 71% with upper ureteric calculi, respectively. The lithotripsy time was only 8.6 minutes for stones < 1cm and 14.8 minutes for stones ranging from 1.1 to 2.0cm. Completely fragmented stones cleared spontaneously within two weeks in 98% of cases and all patients were free of calculi one month after the procedure. Retreatment with the lithoclast was required in six patients for large residual fragments. The mean hospital stay was 1.2 days. Complications were encountered in 6.8% of cases and were managed conservatively. Conclusions: Pneumatic lithotripsy is an excellent form of treatment for lower and mid-ureteric calculi. It is a very reliable, highly effective, rapid and safe procedure

INTRODUCTION
Various methods have been used for the removal of ureteric calculi. The advent of extra-corporeal shock wave lithotripsy (ESWL) in the early 1980s and ultrathin ureteroscopes in the early 1990s have revolutionised the management of these calculi. ^1-3 Due to significant changes in the treatment options, open surgical stone extraction is almost non-existent nowadays, comprising only 0.5% of all cases of ureteric calculi.⁴ The success rate of in-situ ESWL of upper ureteric stones is approximately 84%. With location problems and impacted stones in the middle ureter and small stones in the lower ureter, the success rate is even lower and ranges between 58% and 72%.⁵ Due to the high rate (38%) of retreatment sessions in ESWL, ureteroscopy has become the method of choice for the quickest way of rendering patients stone-free.6 Various forms of energy including electrohydraulic, ultrasonic, laser and pneumatic energy have been used for breaking stones; pneumatic lithotripsy has been found the most effective, safe and economical mode of treatment. ^7-9

PATIENTS AND METHODS
From April 1994 to September 2000, we have treated 493 patients with ureteric stones with intracorporeal pneumatic lithotripsy. These stones failed to pass spontaneously over a minimum period of two weeks. Patients of all age groups from both sexes were included. All had a full blood count, urine analysis, ultrasonography, plain radiography of the abdomen and intravenous urography, unless contraindicated. Number, site, size and laterality of ureteric stones were noted. Ureteroscopy was performed with 7Fr.Wolf 435mm long ureterorenoscope. Seven patients, in whom ureteroscopy failed and stones could not be accessed for application of pneumatic energy, were excluded from the study.

Once the stone was localised, it was treated with the Swiss lithoclast. It is a mechanical intracorporeal lithotripter and works on the principle of the “jack hammer”. It uses pneumatic energy, which is generated in the hand piece by the movement of a bullet facilitated by air pressure controlled in the form of pulses from the generator. This pneumatic energy is directly transmitted from the hand piece to the stone by a direct contact rigid probe, resulting in the breakage of the stone. The goal was to fragment stones into small pieces of around 1-2mm in size, which would pass out spontaneously in the urine. The stones were broken at a pressure of 3.0 bar and a single pulse was applied in most of the cases. All cases were done without flouroscopy. A plain radiograph of the abdomen and/or retrograde pyelography was performed the next day to document stone fragmentation and large residual or migrated fragments. Patients were followed-up at two weeks and one month after the treatment for stone clearance. Retreatment with pneumatic energy was carried out in case of large residual fragments, which failed to clear in two weeks’ time. The results were analysed as for lithotripsy time, fragmentation in respect of site and size of stones, stone migration, stone clearance, success rate and hospital stay.

RESULTS

Age and sex
The age ranged from eight years to 76 years. Most individuals were in the 31-40 years age group. Mean age was 38.24 years with a standard deviation of 11.47. Male to female ratio was 2.5 to 1, with 352 males and 141 females.

Site of stone
We have treated 529 ureteric stones in 493 patients. Most of the stones were in the lower ureter (63%). Table 1 shows the site and laterality of the stones, respectively. The stones were bilateral in 15 patients and there were more than one stone in 26 patients. In 11 patients there were multiple stones in one ureter.

Size of stone
Table 2 shows the distribution of cases according to the size of stones.

Stone fragmentation
Table 3 shows the complete fragmentation of stones with lithoclast with respect to the site of the stone. In the lower ureter complete fragmentation was achieved in 99% of cases, while it was 97% and 71% of cases in the middle and upper ureter, respectively. In six patients, residual fragments in the ureter were big and were broken with the lithoclast in second sessions.

Stone migration
Table 3 shows that in 42 patients, big stone fragments migrated to the kidney which were later cleared with ESWL. The majority of the stones that migrated to the kidney were from the upper ureter (37 out of 42).

Lithotripsy time
Once localised, the lithoclast was very effective in breaking the stones. On average it took only 8.6 minutes to fragment stones of less than 1cm and 14.8 minutes for stones ranging between 1.1-2.0cm (Table 2).

Stone clearance
Stones migrated upwards to the kidney in 42 of a total of 493 patients. Out of the remaining 451 patients, stones cleared completely in 98% (442 out of 451) of cases at two weeks. Of the remaining nine patients, intracorporeal lithotripsy had to be repeated in six patients as residual fragments were relatively large. All patients were clear of stones at one month after lithoclasty.

Complications
The number and variety of complications encountered were very few and are shown in Table 4.

Hospital stay
The hospital stays ranged 1-5 days and the average stay was 1.2 days.

Ancillary procedures
A ureteric catheter was placed for one day in 371 patients, while a pigtail catheter was inserted in 103 patients.

Balloon dilatation of the ureteric orifice was performed in six patients and in another six patients large pieces were extracted with a dormia basket under vision. ESWL was performed in 42 patients with migrated residual stones.

DISCUSSION
The Swiss lithoclast was developed in Switzerland in 1989 and clinical results of its use in fragmenting urinary stones were published in the early 1990s. ^10,11 Thereafter, it has been used widely all over the world. ^5,7,12-15 Our results show that it is very effective in breaking calculi. We have achieved 99%, 97% and 71% complete fragmentation of stones in the lower, mid and upper ureters, respectively. In some patients incomplete fragmentation was not because of inefficiency of the lithoclast but because the stone fragments became inaccessible due to their upward migration to the kidney. Rarely, poor vision, ureteral injury and massive stone burden were responsible for partial stone fragmentation. In four patients the stones were pushed back in to the upper calyces where stones were completely fragmented on three occasions, as they still remained accessible. The lithoclast has proved quite rapid in breaking stones and the time spent on the pneumatic lithotripsy was very minimal (Table 3). Our observations are similar to those of others. ^5,13 However, we have observed that the time taken to break hard stones was longer, as compared with that of soft stones. We could break the stones into very small pieces by spending some extra time, in order to achieve rapid and early clearance in 98% of cases within two weeks. The spontaneous passage of sand was relatively pain-free in the majority of cases. We have applied energy in single pulses as we observed that these were more powerful in breaking stones, compared with multiple pulses. Multiple pulses were used only to achieve finer fragments in the lower and mid-ureter, where stone burden was considerable. Moreover, we observed that single pulses were more helpful in preventing the stones from going up into the kidney, compared with multiple pulses. Stone migration was negligible from the lower (0.9%) and mid-ureter (3%), compared with stones in the upper ureter (29%).

Upper ureteric stones were subjected to primary treatment with the lithoclast as the aim of the study was to compare its efficacy as a monotherapy in various parts of the ureter. Moreover, ESWL was not a preferred choice as the kidneys were obstructed in most of the cases and stones were impacted. Urgent relief of obstruction with ESWL is not often achieved due to impaction of stones, multiple treatment session requirement and the long clearance time required. ^5,6 Placement of JJ stents is necessary to bypass the site of obstruction as a prerequisite for ESWL in such cases. In our experience it is not free of morbidity, particularly if we try to push a guide wire alongside an impacted ureteric calculus. There is inherent risk of either ureteric perforation with overzealous guide wire manipulation or failure to bypass the stone. We found it safer to directly treat the stone insitu with pneumatic energy resulting in immediate relief of obstruction. The majority (88%) of the stones that had migrated to the kidney were from the upper ureter (37 of 42 cases). The manoeuvres that we found helpful for preventing stone migration were use of single pulse, positioning of the patient with the head-end of the table elevated, stoppage of the irrigating fluid and use of baskets and ureteric occlusion balloons. In the case of baskets, the stones become entrapped, the outer cover is removed and it is possible to pass a 0.8-1mm lithoclast probe alongside the inner metallic wire of the basket through the ureteroscope to completely break the stone. Usage of balloons for preventing upward migration of stone is not cost-effective in our circumstances, as these usually rupture during the first procedure. Moreover, it is time consuming, may push the stone further up into the kidney and sometimes it is difficult to progress the ureteroscope alongside a 5 Fr. balloon catheter. Dretler (2000) has recently introduced the use of “ balloon on a wire” (single channel .038wire with attached balloon) for this purpose. ¹⁶

Our study also included five children below the age of 15 years, successfully treated with intracorporeal lithotripsy. No special problems were encountered and stone clearance was achieved in single sessions. It has been reported that ureteroscopy in children can be performed without dilatation and stone removal does not involve more complications, as compared with such procedures performed in adults. ¹⁷

We do not have the facility of fluoroscopy in our unit and did not find any limitation in ureteroscopy and pneumatic lithotripsy due to its nonavailability. We did not place a guide wire as a safety wire and never attempted to bypass the stone before pneumatic treatment. The guide wire was only used to enter the ureter, reach the site of stone and placement of an open-ended ureteric catheter or JJ stent after completion of the stone treatment. We treated the stone with single pulses into fine pieces, up to the size of the tip of the probe, to pass out spontaneously. We have never attempted to remove large pieces intact with the help of stone forceps; our use of the basket was also very limited. These manoeuvres are in a way helpful to prevent intra-operative complications. There is a morbidity associated with the overzealous manipulation of a guide wire, lithotripsy probe or the use of forceps and baskets for stone retrieval.

We have found lithoclasty to be a very safe procedure. The complications encountered were minimal. Significant haematuria was observed in 1.6% of cases. Sepsis resulting in fever was associated with 2.6% of cases. Postoperative tenderness was present in nine patients; however, ureteric perforation was documented in only four patients. The availability of ultrathin ureteroscopes and newer modalities for intracorporeal stone treatment has markedly reduced the rate of complications. Stoller et al (1992) encountered 19% of complications in stone extractions with 9.5 to 12.5 Fr. ureteroscopes, including 15.4% perforations as compared with only 0.8% in our study. Most of the complications in our study were not because of the equipment used but because of the procedure. Hofbauer observed in 1995 that in pneumatic lithotripsy perforation is caused by the over-zealous manipulation of the tip of the metal probe and lesions are small, as compared with injuries inflicted by expanding shock waves of electrohydraulic energy.⁸ We have observed that, in addition to ureteroscopic injuries, application of energy to stones against the wall of the ureter (and not in the line of the ureter) in large lower ureteric calculi can also cause ureteric injuries. It has been documented in many experimental and clinical studies that pneumatic energy is very safe as compared with electrolydraulic, ultrasonic and laser lithotripsy. ^7-9,18,19 The probes used in the lithoclast for pneumatic lithotripsy are reusable and can be used till they are damaged with no reduction in probe performance as proved by longevity tests. ²⁰ Instrument failure occurred on only five occasions. On three occasions because of leakage of water into the hand piece and twice due to breakage of the probes. In all cases replacing the alternative hand piece or the use of a new probe enabled the procedures to be carried out successfully. In lithotripsy of 529 stones, we have broken only two probes of 1mm size. It broke near the head in both cases. There was no other recurring cost during the last six years except for probe replacement. Because of the simplicity and safety of the procedure, the mean hospital stay was 1.2 days and most patients returned to work within a couple of days.

CONCLUSION
Intracorporeal pneumatic lithotripsy is an excellent form of treatment for lower and mid ureteric calculi. It can be combined with ESWL for achieving good results in upper ureteric stones. Lithoclasty is not only a simple, reliable, highly effective, rapid and safe procedure but at the same time it is cost effective.

REFERENCES
1. Holden D, Rao PN. Ureteral stones. The results of primary in situ extracorporeal shock-wave lithotripsy. J Urol 1989; 142: 37-39
2. Marberger M, Hofbauer J, Turk C, Albrecht W. Minimally invasive therapy of ureteric calculi. Min Invas Ther 1992; 1: 159-67
3. Stoller ML, Wolf Jr JS, Hofmann R, Marc B. Ureteroscopy without balloon dilation: an outcome assessment. J Urol 1992; 147: 1238-42
4. Stenzl A, Seibold J, Peschel R, Hobisch A, Anetschek G, Bartsch G. Pneumatic lithotripsy with an optional suction device (Lithovac) for treatment of ureteral stones. Jap J Endourol & ESWL 1996; 9: 59-62
5. Hofbauer J, Hobarth K, Margberger M. Lithoclast: New and inexpensive mode of intracorporeal lithotripsy. J Endourol 1992; 6: 429-32
6. Hofbauer J, Tuerk C, Hobarth K, Hasun R, Marberger M. ESWL in situ or ureteroscopy for ureteric stones? World J Urol 1993; 11: 54-58
7. Naqvi SAA, Khaliq M, Zafar MN, Rizvi SAH. Treatment of ureteric stones: Comparison of laser and pneumatic lithotripsy. Br J Urol 1994; 74: 694-98
8. Hofbauer J, Hobarth K, Marberger M. Electrohydraulic versus pneumatic disintegration in the treatment of ureteral stones: a randomized, prospective trial. J Urol 1995; 153: 623-25
9. Denstedt JD. Intracorporeal lithotriptors. In: Smith AD, Badlani GH, Bagley DH, Clayman RV, Jordan GH, Kavoussi LR et al (eds). Smith’s textbook of endourology, Vol.I. Missouri: Quality Medical. 1996: 60-77
10. Lanquetin JM, Jichlinski P, Favre R, von Niederhausern W. The Swiss lithoclast. J Urol 1990 part 2; 143: 179A, abstract V-032
11. Wisard M, Jichlinski P, Languetin J-M, Favre R, von Niederhausern W. Premiere evaluation clinique du lithoclaste CHUV a energie balistique. Helv Chir Acta 1991; 58: 319-21
12. Denstedt JD, Eberwein PM, Singh RJ. The Swiss lithoclast: a new device for intracorporeal lithotripsy. J Urol 1992; 148: 1088-90
13. Schulze H, Haupt G, Piergiovanni M, Wisard M, von Niederhausern W, Senge T. The Swiss lithoclast: a new device for endoscopic stone disintegration. J Urol 1993; 149: 15-18
14. Wadhwa SN, Hemal AK, Sharma RK. Intracorporeal lithotripsy with the Swiss lithoclast. Br J Urol 1994; 74: 699-702
15. Skokeir AA. Transurethral cystolitholopaxy in children. J Endourol 1994; 8: 157-60
16. Dretler SP. Preventing proximal ureteral stone migration: a balloon on a wire, Presented in AUA 95th annual meeting. April 29 to May 4, 2000 Atlanta, Georgia
17. Schroff S, Watson GM. Experience with ureteroscopy in children. Br J Urol 1995; 75: 395-400
18. Piergiovanni M, Desgrandchamps F, Cochand-Priollet B, Janssen T, Colomer S, Teillac P et al. Ureteral and bladder lesions after ballistic, ultrasonic, electrohydraulic and laser lithotripsy. J Endourol 1994; 8: 293-98
19. Denstedt JD, Razvi HA, Rowe E,Grignon J, Eberwein PM. Investigation of the tissue effects of a new device for intracorporeal lithotripsy: The Swiss lithoclast. J Urol 1995; 153: 535-37
20. Meyer WW. Basic studies in pneumatic lithotripsy with Swiss lithoclast. Jap J Endourol ESWL 1996; 9: 63-66

Copyright: 19 March 2003