Endoscopic Laser Lithotripsy: Safe, Effective Therapy for Ureteral Calculi

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ENDOSCOPIC LASER LITHOTRIPSY: SAFE, EFFECTIVE THERAPY FOR URETERAL CALCULI PETER FUGELSO

AND

PETER M. NEAL

From the Lithotripsy Department, Saint Joseph Medical Center, Burbank, and Kaiser Permanente Medical Center, Los Angeles, California

ABSTRACT

At our lithotripsy department more than 400 patients with renal or ureteral calculi have been treated with a pulse-dye laser for stone disease. We review our experience during an 11-month period when a total of 223 patients was treated. Of these patients 204 whose ureteral calculi were treated by laser lithotripsy are available for followup. The data in this series demonstrate that a miniaturized ureteroscopic system is of paramount importance in laser lithotripsy, allowing access into the ureter without dilation in the majority of patients (165 of 204). Lack of dilation is associated with a decrease in pain and postoperative hospitalization. Satisfactory stone fragmentation was accomplished in 198 of 204 procedures in this series with use of the laser alone. A low complication rate was observed. Endoscopic laser lithotripsy is a safe, reliable and cost-effective method of therapy for ureteral calculi in a community hospital setting. KEY WORDS:

calculi, kidney, ureter, laser surgery, lithotripsy

Our lithotripsy department is equipped with Dornier HM-3* and MPL-9000* extracorporeal shock wave lithotriptors, a Candela MDL-1 LaserTripter,t and other electrohydraulic and ultrasonic generators for endoscopic intracorporeal lithotripsy. All equipment is located in 1 treatment area of the hospital. During the preceding 3 years approximately 1,500 patients have been seen yearly and an average of more than 1,100 procedures has been performed each year. The Candela MDL-1 device (since upgraded to the MDL 2000 instrument) was obtained on February 1, 1989 and the 223 laser lithotripsy procedures performed during the last 11 months of 1989 are the nucleus of this report. MATERIALS AND METHODS

From 223 procedures in which the Candela LaserTripter was used patients were available for followup in 211 instances. Of these 211 procedures 204 were performed as therapy for ureteral calculi and form the basis of this report. There were 132 procedures performed in male and 72 in female patients; 103 were on the right and 101 on the left sides. Average patient age was 48 years, with a range of 8 to 84 years. Measured radiographically in its longest dimension the average stone size was 11 mm. General anesthesia was used for all procedures in this series. The stones were located within the upper ureter in 34 cases, mid ureter in 31 and lower ureter in 139. The upper ureter is defined as that portion beginning at the ureteropelvic junction and extending downward to a line equal to the lower pole of the kidney. From this point to the iliac vessels is defined as the middle ureter and below the vessels is defined as the lower ureter. Treatment of upper and middle ureteral calculi in most instances began with an attempt to move the stone back into the kidney and/or place a stent or catheter to facilitate extracorporeal shock wave lithotripsy (ESWL*). The 65 upper and middle ureteral calculi in this series represent impacted calculi that could not be moved retrograde to the kidney for ESWL monotherapy. For treatment of the 139 lower ureteral calculi laser lithotripsy was the only modality used in 100 cases (72% ). An additional treatment form, usually basket extraction of Accepted for publication October 19, 1990. * Dornier Medical Systems, Inc., Marietta, Georgia.

t Candela Laser Corp., Wayland, Massachusetts.

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fragments, was used in 28% of the cases. ESWL was not used as a treatment modality in any of the lower ureteral calculi. Maximum power settings used for satisfactory fragmentation were 30 mJ. in 5 cases, 40 mJ. in 56 and 50 mJ. in 64, while in only 78 of 204 procedures (39%) was the maximum setting of 60 mJ. used. The pulse repetitions were usually set at 5 to 7 pulses per second. An average of 1,231 shock waves was used, ranging from 6 to 10,229 pulses. A miniaturized 7.2F endoscope, the MiniScope,t with 2, 2.lF (0.028-inch) working channels, a fiberoptic viewing system and semirigid construction, 1 is ideal for delivering the laser fiber and was used in the majority of cases (174). The Wolf 8½F instrument was used in 13 cases, the Wolf 9½F device in 4 and the flexible (all types) device in 23. More than 1 type of instrument was used in several procedures. Ureteral dilation was required in 27 of 174 patients (16%) when the Candela MiniScope alone was used. When larger endoscopes were used dilation was necessary in 12 of 40 procedures (30% ). Sten ts were used postoperatively in 132 of 204 procedures (65%). RESULTS

Of the 65 upper and mid ureteral calculi in this series 48 (74%) were treated with in situ ESWL and laser lithotripsy with the patient under the same anesthetic, with ESWL usually preceding the laser therapy. Of these 65 patients 61 (94%) became stone-free with the initial treatment. Of 139 patients with lower ureteral calculi 126 (91 % ) became stone-free after the initial procedure. Nine of 13 patients who had residual stone had undergone simultaneous ESWL for other upper tract calculi. In only 4 of 13 procedures could the stone be visualized and lasered but not satisfactorily fragmented. These 4 procedures involved 2 difficult cases and each was successfully treated on the third attempt. All stone types (calcium oxalate monohydrate and dihydrate, struvite and uric acid) fragmented satisfactorily except for cystine. In this series 2 of 4 cystine calculi required electrohydraulic lithotripsy in addition to the laser for fragmentation. Monohydrate calculi fragmented with no particular difficulty. Our experience and that of others 2 demonstrate that stone fragmentation is more dependent on the number of shock waves than on stone composition or the laser power setting. Complications from these procedures included infection in 11 patients, a perforated ureter in 5, urinary retention in 2,

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stone migration in 2, stent migration in 1 and pulmonary aspiration in 1. Postoperative infection was a serious complication only once and was associated with significant ureteral perforation requiring percutaneous nephrostomy drainage for 10 days. No open procedures were performed on any patient. There are no known ureteral strictures. When contacted during followup 52 of 204 patients (25%) stated that they experienced pain postoperatively but only 40 (20%) actually took any medicine for pain relief after the procedure. Of 44 patients hospitalized postoperatively 17 were in the hospital for various reasons preoperatively and only 27 (13%) required hospitalization as a direct result of the procedure. Of the 39 patients in whom ureteral dilation was necessary 17 (44%) reported pain and 11 (28%) were hospitalized. DISCUSSION

Multiple recent articles have attested to the increasing use of direct vision ureteroscopy and calculus fragmentation by laser lithotripsy as the treatment of choice for lower ureteral calculi, and as an important adjuvant treatment for stones at other ureteral locations. 3 - 6 These articles contrast with ureteroscopic experience reported only a few years previously 7- 10 when electrohydraulic lithotripsy was the energy source most often used. Two other large series reported hospitalization rates of 2.3 9 and 2.9 10 days, while the fragmentation rates with electrohydraulic lithotripsy were slightly lower than we report. Our own experience with ureteroscopy began in 1981 and progressed from direct vision basket extraction to ultrasonic fragmentation, and then to electrohydraulic lithotripsy. Use of ultrasound was quickly abandoned because of the larger ureteroscope required and frequency of ureteral perforation. Electrohydraulic lithotripsy fragments ureteral calculi well but it is associated with a higher incidence ofureteral damage than with laser lithotripsy in our experience and that of others. 3 • 11 • 12 With the development and availability of the Candela MiniScope, laser lithotripsy has become the energy source of choice in our department. Our experience demonstrates decreased hospitalization and pain, and suggests a lessening of ureteral damage with the use of laser lithotripsy, paralleling experience reported previously. In the use of the Candela MiniScope and laser several technical suggestions are helpful. Either saline or water can be used as an irrigation solution and should be under pressure (300 to 400 mm. Hg) to ensure adequate flow rates. Usually, the pressurized flow rate will act to open the ureteral orifice sufficiently for introduction of the ureteroscope without other dilation. For small stones in the distal ureter or intramural tunnel the Candela MiniScope is introduced directly without dilation or a guide wire to avoid dislodging the calculus. As soon as ureteral access is obtained the irrigant flow is decreased to a minimum, and the Candela LaserTripter is set at low power (40 mJ.) and repetition rate (6 per second). These steps are necessary to avoid cephalad migration of small calculi or fragments that may be impossible to locate if ESWL is necessary. With larger or impacted stones in the lower ureter a guide wire is placed as a first step. Almost universally, a 0.035-inch angled Terumo Glidewire,* a hydrophilically coated radiopaque plastic torque wire, is used. This guide wire has the ability to be directed past almost any impacted stone without ureteral damage. Attempts are made to encourage migration back to the kidney for ESWL if the stone moves easily. Otherwise the ureteroscope is introduced and the stone is fragmented as mentioned previously using the same techniques to prevent the smaller fragments from migrating cephalad. Ifureteral dilation is necessary, polytetrafluoroethylene (Teflon) ureteral dilatorst are passed over the guide wire under fluoroscopic control to a diameter 2F greater than the ureteroscope that will be used. Larger dilation is unnecessary and * Microvasive Inc., Watertown, Massachusetts.

t Cook Urological, Spencer, Indiana.

visually is more traumatic to the ureter. Balloon dilation of the intramural ureter is almost never required. If flexible ureteroscopes are to be used a Finlayson sheath of appropriate size is introduced over the guide wire under fluoroscopic vision. The Finlayson sheath incorporates a tapered obturator that will act as its own dilator if necessary, and the flexible instrument can then be passed through the sheath alongside the guide wire. Impacted stones in the upper and middle ureter have a high rate of failure with ESWL alone compared with stones at other locations. These calculi also can be difficult to manage with laser lithotripsy monotherapy. However, a combination of the 2 procedures yields excellent results. In our series, in most instances attempts were made to move the stone back into the kidney, and if that maneuver failed catheters or stents were placed and ESWL was performed. If there was less than adequate fluoroscopic evidence of pulverization after ESWL the patient was returned to the cystoscopy table and laser lithotripsy was done. The fractures in the calculus from ESWL made the laser rapidly effective and allowed for reduction in size and disimpaction of the fragments from action of the laser and irrigation with the ureteroscope. This combined therapy is much more rapid if ESWL is performed first. Alternatively, endoscopic laser lithotripsy can sometimes be used to disimpact a ureteral calculus and allow the stone to be manipulated back into the kidney for ESWL at that location. It sometimes is necessary to pass either the Candela MiniScope or a flexible ureteroscope over a guide wire to straighten the ureter or define the ureteral lumen. For these purposes a 0.025-inch Terumo Glidewire is used. This guide wire is small enough to pass through any of the working channels and still permit adequate irrigant flow. It has the advantage of not kinking and its hydrophilic coating allows the ureteroscope to slide easily over the guide wire. All stone fragments are decreased to 2 mm. or less if possible. Size can be judged by comparing the fragment to the indwelling guide wire or laser fiber, since the focal length of the lens system in the ureteroscope can cause apparent magnification. Unless it is impossible to fragment the calculus completely no attempt is made to remove the smaller debris. Repeated basketing, and ureteroscope introduction and withdrawal appear visually to be traumatic to the ureter and our experience supports the conclusion that there is a decrease in postoperative discomfort if instrumentation is kept to a minimum. If there is significant ureteral perforation the procedure should be terminated and completed at another operative session. Either a stent or a percutaneous nephrostomy tube should be left in place. For temporary stenting a stiff 6F polyurethane material is preferred. t A pull string is used only in male patients, since even slight displacement in female patients causes incontinence and may mandate early removal. All stents should be positioned with fluoroscopy and the shortest possible stent should be used. All ureteroscopy is done with a miniature endoscopic video camera and the images are projected on video monitors. There are several advantages to working with a video image. It allows a much more comfortable posture invaluable for long or difficult procedures. The visual intensity of the laser discharge is decreased. Technicians, nurses and residents can also observe the procedure, and be of much greater assistance. An assistant with a hand on the abdomen or flank can often direct the calculus into the visual field while observing the monitor. 4 We have found video surgery to be associated with a short learning curve. CONCLUSIONS

Minimal ureteral dilation, miniaturized endoscopes and as little intraureteral instrumentation as possible will produce relatively painless, highly efficient outpatient therapy for appropriate ureteral calculi. Laser lithotripsy becomes costeffective13· 14 when compared with other energy sources because

ENDOSCOPIC LASER LITHOTRIPSY FOR URETERAL CALCULI

of the decreased hospital stay and absence of significant complications. The Candela MDL-1 LaserTripter produces sufficient energy to fragment almost all ureteral calculi. The device is dependable with low maintenance and no mechanical failures in our experience. REFERENCES

1. Dretler, S. P. and Cho, G.: Semirigid ureteroscopy: a new genre. J. Urol., 141: 1314, 1989. 2. Atala, A., Pumphrey, J. A. and Steinbock, G. S.: Pulsed-dye laser fragmentation of urinary and biliary calculi in vitro. J. Endourol., 4: 175, 1990. 3. Dretler, S. P.: An evaluation of ureteral laser lithotripsy: 225 consecutive patients. J. Urol., 143: 267, 1990. 4. Watson, G. M. and Wickham, J. E. A.: The development of a laser and a miniaturized ureteroscope system for ureteric stone management. World J. Urol., 7: 147, 1989. 5. Higashihara, E., Rorie, S., Takeuchi, T., Kameyama, S., Asakage, Y., Hosaka, Y., Honma, Y., Minowada, S. and Aso, Y.: Laser ureterolithotripsy with combined rigid and flexible ureterorenoscopy. J. Urol., 143: 273, 1990.

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6. Morgentaler, A., Bridge, S. S. and Dretler, S. P.: Management of the impacted ureteral calculus. J. Urol., 143: 263, 1990. 7. Daniels, G. F., Jr., Garnett, J. E. and Carter, M. F.: Ureteroscopic results and complications: experience with 130 cases. J. Urol., 139: 710, 1988. 8. Denstedt, J. D. and Clayman, R. V.: Electrohydraulic lithotripsy of renal and ureteral calculi. J. Urol., 143: 13, 1990. 9. Blute, M. L., Segura, J. W. and Patterson, D. E.: Ureteroscopy. J. Urol., 139: 510, 1988. 10. Lingeman, J. E., Sonda, L. P., Kahnoski, R. J., Coury, T. A., Newman, D. M., Mosbaugh, P. G., Mertz, J. H. 0., Steele, R. E. and Frank, B.: Ureteral stone management: emerging concepts. J. Urol., 135: 1172, 1986. 11. Watson, G., Murray, S., Dretler, S. P. and Parrish, J. A.: An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter. J. Urol., 138: 199, 1987. 12. Dretler, S. P.: Laser lithotripsy: a review of 20 years of research and clinical applications. Lasers Surg. Med., 8: 341, 1988. 13. Nesbitt, J. A. and Drago, J. R.: Extracorporeal shock wave lithotripsy versus ureteroscopic laser lithotripsy: a cost comparison analysis. J. Endourol., 3: 47, 1989. 14. Cohen, J. K., Berg, G. and Benz, T. B.: Cost effectiveness of the 504 nannometer pulse dye laser in the treatment of urinary stone disease. J. Urol., part 2, 143: 268A, abstract 319, 1990.