Mechanisms responsible for diminished fragmentation of ureteral calculi: an experimental and clinical study

The efficacy of early extracorporeal shockwave lithotripsy for the treatment of 5 to 10 mm upper ureteral stones: An observational study

This study aimed to determine the effectiveness of extracorporeal shockwave lithotripsy (SWL) performed in the early period (within the first 24 hours). Data of patients who underwent SWL with a diagnosis of unilateral radiopaque 5 to 10 mm upper ureteral stones were retrospectively examined. Patients were divided into 2 groups. Group 1 (early SWL) consisted of patients with SWL performed within 24 hours after the onset of colic pain (<24 hours), while group 2 (deferred SWL) comprised patients with SWL performed 24 hours or more from the onset of pain (≥24 hours). The primary endpoint of the study was planned to determine 1-month SFR in both groups. The secondary endpoint was determined to be the factor affecting SWL success. The mean age of 216 patients (130 men, 86 women) included in this study was 46.5 ± 12.1 years. SFR within 1 month was detected in 175 patients (81%). In the early SWL group, the average number of SWL sessions was fewer (1.26 vs 1.83 P = .026) and the time to the stone-free state was shorter (11 vs 15.4 days P = .044). SFR within 1 month was higher in the early SWL group (85.5% vs 71.8% P = .036). In multivariate analysis, stone size, Hounsfield Units, and early SWL were predictive factors for SWL success. Performing SWL within the first 24 hours is highly effective in patients with symptomatic 5 to 10 mm upper ureteral stones.

The transgluteal approach to shockwave lithotripsy to treat distal ureter stones: a prospective, randomized, and multicenter study

PURPOSE

We compared the outcomes of SWL to treat distal ureter stones with regard to the conventional prone and supine positions using the transgluteal approach through the greater sciatic foramen.

METHODS

A prospective, randomized, single-blind, and multicenter study was conducted between October 2014 and July 2015. The inclusion criteria were radio-opaque distal ureter stones with a maximum diameter of 0.5-2 cm as measured on a CT scan. The included 160 patients were randomly assigned to two groups: the prone group (n = 80; treated in the conventional prone position) and the transgluteal group (n = 80; treated in the supine position using a transgluteal approach). In the latter group, the focused shock wave was transmitted through the greater sciatic foramen with the head positioned at a 40° angle to the vertical. "Stone-free" was defined as the complete clearance of stone fragments, assessed using a CT scan at 2 weeks after treatment. Overall satisfaction was self-reported using a 0-5 Likert scale.

RESULTS

The overall efficacy was 66.9%. The stone-free rate was significantly higher in the transgluteal group (72.6%) than in the prone group (54.7%; odds ratio 2.413, 95% CI 1.010-5.761, P = 0.023). No serious adverse events due to treatment were observed in either group. The satisfaction score of the transgluteal group was 4.21 ± 0.81, and 83.6% were willing to repeat the same procedure if necessary.

CONCLUSIONS

SWL using the transgluteal approach via a supine position through the greater sciatic foramen was more effective than via the conventional prone position. Furthermore, this approach provided a comparably safe and satisfactory procedure.

Comparison of treatment outcomes according to output voltage during shockwave lithotripsy for ureteral calculi: a prospective randomized multicenter study

PURPOSE

To investigate the effect of fixed versus escalating voltage during SWL on treatment outcomes in patients with ureteral calculi (UC).

METHODS

A prospective, randomized, multicenter trial was conducted on 120 patients who were diagnosed with a single radiopaque UC. The patients were randomized into group C (n = 60, constant 13 kV, 3,000 shock wave, 2 Hz) or group E (n = 60, 11.4-12.0-13 kV per 1,000 shock waves, 2 Hz). They were evaluated by plain abdominal radiography and urinalysis at 1 week after a single session of SWL, and repeat SWL was performed if needed. The primary endpoint was stone-free rate at 1 week (SFR1) after SWL. Secondary endpoints were post-SWL visual pain score (VPS), oral analgesic requirements during 1 week, and cumulative SFRs after the second and third sessions of SWL.

RESULTS

Groups C and E were well balanced in terms of baseline patients and stone characteristics, including pre-SWL VPS, stone location, and stone size (6.24 ± 1.92 vs. 6.30 ± 2.13 mm). SFR1s were not significantly different between groups C and E (60.0 vs. 68.3%, p = 0.447). Analyses stratified by stone size (<6 vs. ≥6 mm) showed no difference in SFR1 (p = 0.148 vs. 0.808). In the analyses stratified by stone location, group E tended to be more effective in distal UC (81.0 vs. 50.0%, p = 0.052), whereas no difference was seen in proximal UC (p = 0.487). Secondary endpoints were also similar between the two groups.

CONCLUSIONS

Our results suggest that voltage escalation during SWL in UC may not provide superior stone fragmentation compared to fixed voltage.

Immediate or delayed SWL in ureteric stones: a prospective and randomized study

The objective is to compare immediate and delayed SWL as a treatment for ureter stones between 5 and 20 mm. Patients who applied to the emergency department with single, radio opaque ureteric stone of 5-20 mm size were included in the study. Patients were randomized into immediate and delayed SWL groups. SWL were carried out after pain relief in the delayed group. Maximum of three SWL sessions were applied to the patients with stones of 5 mm or bigger in diameter, leaving at least 3 days interval in-between. Stone-free rate after first session was similar in two groups. When CIRF was also considered as success, the success rate of SWL in the immediate SWL group was higher after first session (p = 0.02). Immediate SWL had a greater success rate in upper ureteric stones (p = 0.019). Overall average time required for elimination of stones was shorter in immediate SWL group than delayed SWL group (p = 0.033). The success rate after first SWL session (including CIRF) was 59 % for patients with chronic pain in the delayed group and 100 % for patients with acute pain in the immediate group. According to the hydronephrosis grade, success rates were 71 and 44.4 % for patients with grade 1 or no hydronephrosis in the immediate SWL group, and for patients with grade 2 or larger hydronephrosis in the delayed SWL group, respectively, after first SWL session. Immediate SWL insures stone-free status in a shorter time in cases with renal colicky pain and ureteral stones, particularly upper ureteral stones.

Effect of output voltage distribution on stone comminution efficiency during shockwave lithotripsy in renal or ureteropelvic junction stones: a preliminary study

OBJECTIVE

This study evaluated stone comminution efficiency according to the distribution of the lithotripter output voltage during extracorporeal shockwave lithotripsy (SWL) of renal or ureteropelvic junction (UPJ) stones.

MATERIAL AND METHODS

Sixty-two patients with a single radiopaque renal or UPJ stone of surface area about 50-400 mm(2) were prospectively randomized to receive a total of 2400 shocks per session according to one of three shock protocols: group A, output voltage was increased from 25% to 35% to 45% with 800 shocks per voltage; group B, constant output voltage of 35%; group C, decreasing output voltage from 45% to 35% to 25%. SWLs were carried out using a fourth generation electroconductive lithotripter, the Sonolith Vision, without anesthesia. The stone-free (SF) and success (SF + clinically insignificant residual fragment) rates were assessed.

RESULTS

Patient demographics, body mass index, stone burden, laterality and stone locations were comparable among the three groups. There were no differences in the cumulative success rates (30%, 32% and 35% after the first session for groups A, B and C, respectively; 65%, 50% and 65% after the second session; and 80%, 68% and 75% after the third session). The cumulative SF rates and complications showed no differences among the three groups.

CONCLUSIONS

In this preliminary study, manipulation of the lithotripter output voltage distribution did not affect stone comminution efficiency for renal or UPJ stones. This finding should be confirmed by larger studies including more patients.

Comparative study of extracorporeal shock wave lithotripsy outcomes for proximal and distal ureteric stones

OBJECTIVE

To assess the efficacy of extracorporeal shock wave lithotripsy (ESWL) monotherapy for isolated proximal ureteral calculi and compare it to that for isolated distal calculi.

PATIENT AND METHODS

We treated 68 patients with isolated ureteral stones using MPL 9000. Stones were located in the proximal and distal ureters in 44 and 24 patients, respectively. Patients were stratified according to stone burden and degree of obstruction. Data of all patients were prospectively collected for stone burden, stone localization, number of sessions, number of shock waves, stone-free rates (SFRs), complications, re-treatment rates and auxiliary procedures. Outcomes regarding ureteral localization were compared.

RESULTS

The overall SFR was 85.3% with a 41.2% re-treatment and 17.6% auxiliary procedure rate. The mean number of shock waves applied for each stone was not different among the two ureteral locations. The SFRs were 86.3% and 79.1% for proximal and distal ureteral stones, respectively (P=0.17). For the group with stones <100 mm(2), the SFR was 85.4% and 89.5% for the proximal and distal ureter, respectively. Although the degree of obstruction did not affect SFR of the entire group (P=0.12) and the proximal ureter group (P=0.96), it adversely affected SFR in the distal ureter (P=0.017).

CONCLUSIONS

ESWL outcomes for the ureteral calculi support the use of lithotripsy particularly for stones <100 mm(2). Treatment efficacy was not significantly different among stones localized in proximal and distal ureters. Degree of obstruction did not affect the ESWL outcomes in the proximal ureter, but it adversely affected SFR in the distal ureter.

Shock wave lithotripsy of stones implanted in the proximal ureter of the pig

PURPOSE

Ureteral stones can be difficult to treat with shock wave (SW) lithotripsy. A strategy for lithotripsy of proximal ureteral stones is to push them back into the renal pelvis prior to administering SWs. However, push-back is invasive and not always possible. Since there are few clues to suggest how best to treat ureteral stones with SWs in situ, we developed an animal model for research on lithotripsy for ureteral stones.

MATERIALS AND METHODS

Gypsum model stones were implanted bilaterally in the proximal ureter and renal calix of the pig via percutaneous access. Lithotripsy was performed using a HM3 lithotripter (Dornier Medical Systems, Marietta, Georgia) and stones at each location were treated with the same dose (400 SWs, 20 kV and 30 SWs per minute). Fragments were collected and the percent increase in projected surface area of the particles was determined.

RESULTS

The breakage (mean percent area increase) of stones implanted in the proximal ureter was significantly less than that of stones located in the renal calix treated with the same dose of shock waves (134% vs 327%, p <0.001). Also, stones that were fully confined by the ureter did not break as well as stones located at the ureteropelvic junction. This indicates that the physical environment surrounding a stone can have a significant effect on the efficiency of SW action.

CONCLUSIONS

The observation that stones implanted in the ureter showed decreased breakage compared with stones in the kidney is consistent with clinical experience. This finding is a valuable and even essential prerequisite for any experimental animal model system intended for the study of SW action in the breakage of ureteral stones.

[Ureteral lithiasis, what treatment?]

Extracorporeal shock wave lithotripsy and ureteroscopy are minimal invasive techniques, both of which have definitively become essential for the treatment of ureteral stones resistant to conservative treatment. At the time of evidence-based medicine, no study makes it possible to recommend one of these methods rather than the other. For stones of identical size and location, this review of the literature shows that extracorporeal shock wave lithotripsy and ureteroscopy prove of comparable effectiveness and innocuousness. The urologist thus has two alternatives of which the technical control, the availability of the endoscopes or lithotriptors as well as the desire and comfort of the patients are the factors which condition his choice of the method for the treatment of ureteral stones.

The mechanisms of stone fragmentation in ESWL

Currently, several mechanisms of kidney stone fragmentation in extracorporal shockwave lithotripsy (ESWL) are under discussion. As a new mechanism, the circumferential quasistatic compression or "squeezing" by evanescent waves in the stone has been introduced. In fragmentation experiments with self-focussing electromagnetic shock-wave generators with focal diameters comparable to or larger than the stone diameter, we observed first cleavage surfaces either parallel or perpendicular to the wave propagation direction. This is in agreement with the expectation of the "squeezing" mechanism. Because, for positive pulse pressures below 35 MPa and stones with radii of 15 mm or smaller, cleavage into only two fragments was observed, we developed a quantitative model of binary fragmentation by "quasistatic squeezing." This model predicts the ratio of the number of pulses for the fragmentation to 2-mm size and of the number of pulses required for the first cleavage into two parts. This "fragmentation-ratio" depends linearly alone on the stone radius and on the final size of the fragments. The experimental results for spherical artificial stones of 5 mm, 12 mm and 15 mm diameter at a pulse pressure of 11 MPa are in good agreement with the theoretical prediction. Thus, binary fragmentation by quasistatic squeezing in ESWL as a new efficient fragmentation mechanism is also quantitatively verified.

Primary in situ extracorporeal shock wave lithotripsy in the management of ureteric calculi: results with a third-generation lithotripter

OBJECTIVE

To review the results of primary in situ extracorporeal shock wave lithotripsy (ESWL) for the treatment of ureteric stones using a third-generation lithotripter, the Dornier MFL 5000 (Dornier Medizentechnic, Germany).

PATIENTS AND METHODS

The study comprised a retrospective review of treatment outcome in 180 patients with 196 stones who were treated with primary in situ ESWL, assessing the success of this approach and establishing reasons for failure.

RESULTS

At the 3-month follow-up, 88% of patients were stone-free; 21 patients failed ESWL and were treated by ureteroscopic stone extraction with no complications. Stone-free rates were 90% for upper ureteric, 89% for middle-third and 86% for lower-third calculi. Twenty-one patients required auxiliary procedures in the form of JJ stenting or nephrostomy. Failure of ESWL was associated with stone size (>1.3 cm) but not location or inadequate treatment.

CONCLUSION

Where prompt access to ESWL is available, primary in situ ESWL remains an effective form of treatment for all ureteric calculi, although stone-free rates are lower for larger stones.

Extracorporeal piezoelectric shockwave lithotripsy of ureteral stones: are second-generation lithotripters obsolete?

BACKGROUND

The role of extracorporeal shockwave lithotripsy (SWL) for ureteral calculi is still being debated. We evaluated our results in a large series to clarify the role of this modality.

PATIENTS AND METHODS

A total of 478 patients with solitary ureteral stones were treated by in situ piezoelectric extracorporeal shockwave lithotripsy (SWL) using a Wolf Piezolith 2300 ultrasound-guided lithotripter. Two hundred fifty stones (52.3%) were located in the upper ureter and 228 (47.7%) in the distal ureter. Seventy of the upper ureteral stones were located in the ureteropelvic junction and 180 in the lumbar ureter. The diameter of the stones ranged from 5 to 30 mm. Four hundred sixty-seven patients were followed up for a mean of 4 months.

RESULTS

Four hundred forty patients (94.2%) were stone free after in situ SWL alone. Complete removal of all stone fragments was achieved in 95.4% of the 216 patients with calculi of 5 to 10 mm in diameter, in 94.3% of the 229 with stones of 11 to 20 mm, and in 81.8% of the 22 with calculi of 21 to 30 mm. In situ treatment completely removed 61 of 69 ureteropelvic junction stones (88.4%), 166 of 175 lumbar stones (94.8%), and 213 of 223 distal ureteral stones (95.5%). In situ treatment failed in 27 stones (5.8%). After 4 months, 12 stone fragments and 15 unfragmented stones persisted despite retreatments and required endoscopic procedures. The mean number of sessions and shockwaves per patient was 1.8 and 4884, respectively. Morbidity was low. Renal colic in 57 patients (11.9%) was managed successfully by analgesics. In 36 patients, stone fragments obstructed the ureter; in 28 of these 36 (78%), the obstruction was resolved and the patients were stone free after in situ retreatments alone. All these results were achieved on an outpatient basis without sedation or local or general anesthesia.

CONCLUSION

Piezoelectric SWL is an effective and noninvasive method for eliminating ureteral stones. Second-generation ultrasound-guided lithotripters are not yet obsolete.

Optimizing results of lithotripsy using robust electromagnetic probe

BACKGROUND AND OBJECTIVE

A significant impediment to the measurement of the pressures and forces created by lithotripter shockwaves has been their destructive properties, which have rendered most measuring devices impractical. We have developed and tested a robust electromagnetic probe to measure cavitational forces in vitro in the focal zones of extracorporeal lithotripters. The probe responds to the pressure gradient generated by the radial motion of cavitation bubbles.

MATERIALS AND METHODS

The effects of shockwaves from the Dornier MPL 9000 electrohydraulic lithotripter were measured over the lifetime of multiple electrodes.

RESULTS

The pulse energy from the electrodes dropped off rapidly after approximately 50% of the lifetime quoted by the manufacturer. The electrodes were more efficient at higher power settings. As a result, we altered our protocol for the treatment of ureteral stones to use a higher kilovoltage and a second electrode whenever necessary. Stone-free rates after shockwave lithotripsy (SWL) in situ for stones < 11 mm have increased from 68.2% to 83.3%, and the retreatment rate has dropped from 23% to 15%. Despite significantly higher power settings (23.7 kV v 18.7 kV; P < 0.0001), the need for sedoanalgesia has remained relatively constant (26% v 31%).

CONCLUSIONS

Measurement of cavitational forces from lithotripters using a robust electromagnetic probe is useful in planning treatment strategy. We have demonstrated a clinically measurable improvement since implementing our new treatment protocol. Because the probe responds directly to cavitational forces, it should also prove useful for the objective comparison of different SWL machines.

Characterization of cavitational activity in lithotripsy fields using a robust electromagnetic probe

A robust electromagnetic probe has been used to investigate cavitational activity in vitro in the fields of two extracorporeal lithotripters and one intracorporeal lithotripter. Some aspects of the electromagnetic probe design and characteristics are described. A series of experiments have been carried out with results indicating that the probe head moves in response to the pressure gradient generated by radial motion of cavitation bubbles. Empirical expressions have been derived for the cavitational force acting on the probe head, and for the low-frequency sawtooth pressure wave generated by inertial cavitation. This is the first time that the existence of a low-frequency sawtooth wave produced by inertial cavitation has been described. A linear relationship exists between the negative pressure amplitude of the sawtooth wave and the lifetime of the bubbles. Close to the cavitation site, substantial negative pressure is maintained throughout bubble expansion. This can easily exceed the tensile strength of urinary calculi, and may be considered to be an important mechanism for disintegrating these relatively weak structures. A pilot study has also been carried out involving three patients treated by extracorporeal lithotripsy. Signals similar to those recorded during the in vitro cavitation experiments were detected. We conclude that the electromagnetic probe is capable of detecting and quantifying aspects of cavitational activity in vitro, and potentially also in vivo. The observation that the probe responds directly to the motion of cavitation bubbles, coupled with its ability to detect cavitation at a distance, give it the potential for use in a range of medical and industrial applications.

ESWL Monotherapy

Between February 1988 and December 1995, 1563 consecutive patients who had never previously been treated for ureteral stones were admitted to our hospital: 1535 (98%) underwent primary ESWL (with Lithostar plus) with fractioned doses and 28 (2%) needed primary endosurgery. At present 1327 (87%) patients can be evaluated. Up to 6,000 SW were given to 733 (55%) patients: 93% achieved complete clearance. Of the 594 (45%) patients who completed treatment, 195 (33%) achieved complete clearance with first treatment, 27 (5%) required endosurgery and 372 (62%) were treated again, of whom 279 (75%) were made stone-free. Overall 877 (66%) were stone-free following first treatment; 1156 (87%) following second treatment and 171 (13%) were failures. Lumbar (9% failure) and ≤0.6 cm (6% failure) stones gave higher success rates. Auxiliary pre-ESWL manoeuvres were reduced from 112/352 (32%) prior to 1990 to 75/975 (8%) after 1990, without affecting outcome (failures were 11 and 13.6% respectively). In-situ ESWL is a safe therapy for ureteral stones and in our experience capable of rendering 87% of patients stone-free.

Contemporary management of ureteral stones

The management of ureteral stones has undergone revolutionary changes in the past 15 years. The parallel advances in extracorporeal shock wave lithotripsy, percutaneous and retrograde endoscopic access to the collecting system, and intracorporeal lithotripsy devices almost completely have supplanted the need for a traditional ureterolithotomy. The merits of the various technologies that are available are discussed as they apply to treating calculi in different ureteral segments.

Ureteral calculosis: ESWL in situ and after preliminary manoeuvres

Extracorporeal shock wave lithotripsy is nowadays first choice treatment of ureteral stones. Shock wave generator technology has greatly advanced since the first electrohydraulic lithotriptor was introduced. Third generation lithotriptors combine all these advantages and integrate them into a multi-functional X-ray system. From January 1996 to June 1996, 63 patients (43 male and 20 female) suffering from ureteral calculosis were treated. Stone localisation was in 35 cases (55%) the lumbar ureter, in 3 (5%) the iliac ureter and in 25 (40%) the pelvic ureter. A Storz Modulith SLX lithotriptor with an electromagnetic cylindrical source was used. Easy positioning of the patient and dry coupling make treatment procedures simple. Furthermore, general anesthesia is not required and analgesic sedation (Fentanest and Diazepam) is often unnecessary, especially in ureteral stones.

Emergency ESWL in ureteral lithiasis

Extracorporeal shock wave lithotripsy (ESWL) may be considered first-choice treatment for upper ureteral stones; for lower ureteral stones, an endoscopie approach gives a high success rate but also higher morbidity. Over a period of 18 months in our Department, 275 consecutive patients with ureteral stones underwent ESWL. In 40 patients (14.5%) ESWL was performed within 48 hours of onset of acute renai colie; stone diameters were 7.5 mm average (range 5-20 mm). Ten patients (25%) were treated after ultrasonography and abdomen X-rays, while 30 patients also underwent an I.V.P. Shock waves required for fragmentation were 1503 on average (range 437-2650). All patients were treated after sedation-analgesia. All patients had remission of clinical symptoms after ESWL and one month later were all stone-free at X-ray and ultrasonographic control. Just one complication was observed: a small perineal hematoma that required no treatment. On the basis of our data, emergency ESWL is suggested as a non-invasive, easy-to-perform, well-tolerated treatment giving immediate remission of clinical symptoms. When unsuccessful, it does not preclude endoscopy or open surgery. Emergency ESWL has proved to be the treatment of choice due to the high percentage of total stone elimination, lack of anesthesia, few complications and excellent patient compliance.

Applicability of Iceland spar as a stone model standard for lithotripsy devices

The identification of a universal stone model standard would enable reproducible fragmentation data useful for the design, evaluation, and comparison of various lithotripsy devices. The clinical benefits of such a stone model include the elucidation of setting parameters that would optimize fragmentation strategies. Iceland spar is a pure form of calcite (CaCO3) that was subjected to experimental disintegration by electrohydraulic lithotripsy and extracorporeal shockwave lithotripsy. Iceland spar was fragmented with both lithotripsy methods in a reproducible fashion. The degree of fragmentation was directly related to alterations in either power or shock frequency. Iceland spar is radiopaque, inexpensive, easily obtained, homogenous in composition, and sizable. Iceland spar meets a variety of stone model criteria, warranting its continued investigation as a potential stone model standard.

The case for primary endoscopic management of upper urinary tract calculi: I. A critical review of 121 extracorporeal shock-wave lithotripsy failures

OBJECTIVES

To define those patients with upper urinary tract calculi who are more likely to have an unsuccessful outcome from extracorporeal shock-wave lithotripsy (ESWL).

METHODS

A critical prospective analysis of 121 patients, referred to two university centers after ESWL had been exhausted as a treatment modality for upper urinary tract calculi, was performed. Patients were subdivided into the following groups: failure to clear fragments, failure to fragment, difficulty in calculus localization, and failure due to inherent upper urinary tract obstruction. Other important variables include the type of extracorporeal lithotriptor used, number of treatment sittings before referral, calculus location, calculus composition, patient body habitus, and the imaging leading to and associated with extracorporeal therapy.

RESULTS

Large renal calculi (mean, 22.2 mm) and those within dependent or obstructed portions of the collecting system were frequently referred for endoscopic management after failed ESWL. Steinstrasse can be an extremely morbid complication from ESWL and in this series was associated with irreversible loss of renal function and ureteral stricture disease. Extracorporeal lithotripsy of infectious calculi can be associated with severe septic complication. Inadequate preoperative and intraoperative imaging and morbid obesity were also associated with failure. Second- and third-generation lithotriptors were represented in greater numbers than the Dornier HM-3 in this group of ESWL failures.

CONCLUSIONS

ESWL remains the treatment of choice for moderately sized, uncomplicated renal calculi. Large calculi, those within obstructed or dependent portions of the collecting system, and those composed of calcium oxalate monohydrate, frequently fail ESWL. Training in the more technically challenging aspects of endoscopic lithotripsy must be encouraged.

In-situ ESWL in the treatment of ureteral stones

— 185 patients with ureteral stones were treated with ESWL (118 with lumbar ureteral stones, 63 pelvic, 4 sacroiliac). 182 patients (98.3%) were treated with ESWL in-situ by means of a Dornier MFL-5000 lithotriptor. Stone size varied from 0.6 to 1.4 cm (mean 0.9 cm); 145 patients (86.9%) were stone-free after one treatment. The re-treatment rate was 13% for lumbar ureteral stones, 25% for sacroiliac and 12.5% for pelvic stones. We report no complications. 11 patients (6.04%) had to be treated subsequently with ureteroscopic fragmentation and 4 (2.19%) with open surgery. We conclude that in-situ ESWL is also a safe and effective treatment for distal ureteral stones, for which ureteroscopy is also a successful technique but with higher morbidity, and should therefore be performed in case of failure of ESWL. We have more chance of success if the in-situ treatment is performed as soon as possible.

Comparison of the performance of two pulsed dye lasers using a synthetic stone model

The performance of two pulsed dye laser lithotripters was compared in vitro using a synthetic calculus with gross physical properties similar to natural urinary tract calculi. Synthetic calculi were subjected to 500 shocks at nominal pulse energies of 40, 60, 80, 100 and 120 mJ using a 320 micron. fiber. Three calculi were treated at each energy level on the Technomed Pulsolith and two at each level on the Candela MDL 2000. The pattern of fragmentation was similar with both lithotripters. Increasing the energy level resulted in a linear increase in fragmentation (Pulsolith r = 0.95, MDL 2000 r = 0.99), but fragmentation was greater with the MDL 2000 than with the Pulsolith (6.01 mg/mJ versus 5.00 mg./mJ, p < 0.001). Both lasers fragmented the calculi satisfactorily. We recommend that all users of such lasers acquire a laser meter to allow monitoring of the energy delivered by the fiber tip.

Should upper ureteral calculi be manipulated before extracorporeal shock wave lithotripsy? A prospective controlled trial

Whether all upper ureteral stones must be manipulated before extracorporeal shock wave lithotripsy (ESWL*) is an ongoing controversy. In a prospective trial, symptomatic patients with solitary upper ureteral calculi less than 1 year in duration were alternated between ESWL in situ and pre-ESWL stone manipulation. Pretreatment excretory urograms were assessed for stone size and degree of proximal hydroureteronephrosis, which was graded from zero (no dilatation) to 3 (severe dilatation). Stone manipulation was done with the patient under intravenous sedation and local anesthesia. A total of 4,000 shock waves was given in a single session using Siemens Lithostar Plus, and treatment was repeated on days 4, 15 and 30 if required. The patients were evaluated 3 months after onset of therapy with excretory urogram and urine culture. Seventy patients qualified for the study (group 1-35 in situ and group 2-35 stone manipulation) and were comparable in relation to age and sex, stone size and degree of hydronephrosis. There was no significant difference between the 2 groups regarding the number of sessions (group 1-1.86 +/- 1.2 and group 2-2.03 +/- 1.2) or shock wave requirement (group 1-5,705.8 +/- 3,536.9 and group 2-5,549.1 +/- 3,837.2) for stone fragmentation. The degree of proximal dilatation did not contribute significantly towards the outcome (F ratio 0.675, p = 0.57). A total of 30 patients (85.5%) in group 1 had a satisfactory outcome at 3 months, while 3 (8.5%) had significant residual calculi and 2 stones could not be fragmented. Of the manipulated stones 33 (94%) were successfully cleared, while 2 patients required auxiliary procedures. Ureteroscopy was required in 1 patient for upward migration of the stent. Morbidity in both groups was comparable. We conclude that upper ureteral stones should be treated in situ to avoid the morbidity of manipulation.