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Introduction: To assess the clinical features, outcomes, complications, and cost-effectiveness of shockwave lithotripsy (SWL), flexible ureterorenoscopy (FURS), and percutaneous nephrolithotomy (PCNL) in the treatment of lower pole (LP) stones (10-20 mm) in a large tertiary referral center. Patients and Methods: Consecutive patients treated for solitary LP stones (10-20 mm) between 2008 and 2013 were identified from a prospective database. SWL was used as primary treatment in all cases (following a stone multidisciplinary team assessment), with FURS and PCNL reserved for SWL contraindications, failure, or patient choice. 'Success' was defined as stone free and/or clinically insignificant stone fragments (≤3 mm) at 1 and 3 months follow-up. Effect of anatomy on SWL success was determined from using CT images and regression analysis. Average cost per treatment modality (including additional second-line treatments) was calculated for each group using the National Health Service England 2014/15 National Tariff Healthcare Resource Group codes. Results: Two hundred twenty-five patients were included (mean age 54.9; median stone size 12 mm). One hundred ninety-eight (88%), 21 (9.3%), and 6 (2.7%) patients underwent SWL, FURS, and PCNL as primary treatments, respectively, for median stone sizes of 12, 12, and 20 mm. Overall success rates were 82.8%, 76.1%, and 66.7%, respectively ( p < 0.05). Sixty-three percent of patients undergoing primary SWL were effectively treated after one session. Anatomical analysis determined infundibulopelvic angle and infundibular length to be significantly different in patients effectively treated with SWL ( p = 0.04). The average cost per treatment modality was also significantly lower for SWL (£750) than for FURS (£1261) or PCNL (£2658) ( p < 0.01). Conclusion: SWL is both an efficacious and cost-effective primary treatment for patients with solitary LP stones (10-20 mm). The majority of patients can be effectively treated with primary SWL in a dedicated stone center, with the benefits of a short length of stay, low complication, and auxiliary treatment rates. The referral of such patients to high-volume lithotripsy centers with demonstrable outcomes should be given due consideration. [ABSTRACT FROM AUTHOR]

Purpose: To assess the effectiveness of routine prophylactic antibiotics in the prevention of urinary tract infection (UTI) after extracorporeal shockwave lithotripsy (SWL) and identify predictors of UTI development in a multicenter series of over 10,000 stone cases treated in New Zealand over a 20-year period. Materials and Methods: Patients treated with SWL on the Mobile Medical Technology vehicle between June 19, 1995 and December 1, 2014 were identified. Data collection was undertaken prospectively for patient, stone and treatment characteristics, and, retrospectively, for treatment outcomes. The primary outcome was clinical UTI, defined as development of UTI symptoms requiring antibiotic therapy. Secondary outcomes included urinary sepsis, need for hospital admission due to infectious complications, and length of hospital stay. Multivariate analysis was undertaken to identify factors independently associated with the development of post-SWL UTI. Results: Antibiotic prophylaxis was used in 62.1% (n = 6710) of cases. On comparing patients who received prophylactic antibiotics to those in whom antibiotics were withheld, no significant differences were observed in terms of post-SWL UTI (1.1% vs 1.3%, p = 0.335) or urinary sepsis (0.04% vs 0.15%, p = 0.075). The use of prophylactic antibiotics was not independently associated with post-SWL UTI (OR: 1.269, 95% CI: 0.886- 1.818, p = 0.194). Female gender, larger stone size, and higher number of delivered shocks were predictive of UTI development, but antibiotic prophylaxis did not appear to offer any benefit in this subgroup. Conclusions: Routine antibiotic prophylaxis was not associated with a reduction in clinical UTI after SWL in this cohort of over 10,000 stone cases in New Zealand. [ABSTRACT FROM AUTHOR]

Introduction: Several anatomic and clinical factors have been implicated in the failure rates of shock wave lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model that incorporates the lumbar spine, including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clinical scenario during SWL of upper ureteral stones. We hypothesized that the presence of bone structures in the SWL pathway significantly affects the fragmentation rate. Materials and Methods: An ordnance gelatin (OG) model was conceptualized and created to allow a pig's lumbar spine to be embedded within it. Artificial urinary calculi weighing 2 ± 0.1 g (1.2-cm diameter) were prepared using BegoStone plaster. The trial was divided into two arms: group 1 models had OG only and served as the control and group 2 models had the bone embedded in the gelatin with stone wells placed above the transverse processes. Twenty-four stones per group were subjected to SWL using the STORZ MODULITH SLX-F2 lithotripter, using the same treatment parameters. Fragments were sieved through 2- and 4-mm filters, and the fragmentation coefficients (FC) were calculated. The Mann-Whitney test was used to compare FC between the two groups. Results: The mean fragmentation rate of group 1 was statistically significantly higher compared with group 2 using a 4-mm sieve (43% vs 0.62%, p < 0.001) and the 2-mm filter (18% vs 0.52%, p < 0.001). Conclusions: The presence of bone structures dramatically reduces the fragmentation rate of phantom stones using an OG in vitro model. The OG model is inexpensive and simple to use to simulate clinical situations during SWL. [ABSTRACT FROM AUTHOR]

Objective: To test the hypothesis that shock wave lithotripsy machines vary in their ability to fragment standardized artificial urinary calculi. Materials and Methods: An in vitro test configuration was used to fragment synthetic U-30 Gypsum (U.S. Gypsum, Chicago, IL) stones (mean length 7.1 ± 0.2 mm, mean diameter 6.5 ± 0.07 mm, mean mass 299 ± 16 mg) using the Sonolith i-sys (EDAP TMS, Vaulx-en-Velin, France), Modulith SLX F2 (Storz Medical AG, Tägerwilen, Switzerland), and Piezolith 3000 (Richard Wolf GmbH, Knittlingen, Germany) lithotripters. Gypsum stones were placed at the nominal focus and treated with 250, 500, or 1000 shocks. The residual mass following passage through a 2-mm wire mesh was measured and compared using ANOVA and the Tukey-Kramer HSD test. Results: There was no statistically significant difference between the Modulith SLX F2 and Piezolith 3000 lithotripters for 250 and 1000 shock treatments ( p = 0.34 and 0.31, respectively). The Piezolith 3000 demonstrated the most favorable stone mass reduction for 500 shock treatments (187.4 ± 45.2 mg). The Sonolith i-sys was found to be significantly less effective than the other lithotripters for all shockwave conditions. Furthermore, performance of the Sonolith i-sys decreased beyond a threshold generator electrode age of 6000 shocks. Conclusions: This in vitro study found considerable variability in the ability of lithotripters to fragment synthetic urinary calculi. Synthetic stones were employed to provide a repeatable means of assessing variability in fragmentation efficiency of lithotripters. The Modulith SLX F2 and Piezolith 3000 are broadly equal and resulted in greater fragmentation efficiencies than the Sonolith i-sys. The performance of the Sonolith i-sys deteriorates at 6000 shocks, before the specified lifetime of 20,000 shocks. [ABSTRACT FROM AUTHOR]

Introduction: Extracorporeal shockwave lithotripsy (SWL) has a low complication rate. While serious complications are rare, cardiac arrhythmias, such as ventricular tachycardia, may occur. The etiology of these arrhythmias is poorly understood, but it appears to be due to stimulation of the heart by the shock waves. Objective: This study examines the effect of rotating the patient 15° to 20° when an arrhythmia occurs. Methods: Eight hundred nineteen patients were prospectively evaluated for arrhythmias during SWL. The initial patient position was dependent on the location of the stone and the body mass index (BMI) of the patient. If a sustained arrhythmia developed, treatment was withheld for 2 minutes and then recommenced. If the patient developed an arrhythmia again, the patient was rotated 15°-20° away from the original position and treatment recommenced. Results: Twenty patients developed significant arrhythmias during SWL. Arrhythmias occurred more frequently in patients with a lower BMI ( p < 0.01), of younger age ( p = 0.01), and with right-sided stones ( p = 0.035). After the first rotation, 11 patients had no further arrhythmias, and 4 patients had a reduction of their arrhythmia to unsustained minor arrhythmias that did not require cessation of the treatment. The remaining five patients required a second repositioning. Three of these patients required gated SWL to abolish the arrhythmia. Conclusion: Changing the position of the patient by rotating the patient by 15 to 20° can eliminate arrhythmias that develop during SWL. [ABSTRACT FROM AUTHOR]

Purpose: To produce and validate a predictive model based on CT parameters for calculating the probability of a stone to be visible on fluoroscopy of shockwave lithotripsy (SWL) and to compare its accuracy to that of kidneys-ureters-bladder (KUB) radiography. Methods: We retrospectively analyzed 306 patients (sample group) who underwent an SWL between March 2011 and August 2012. A multivariate analysis of several parameters extracted from the preoperative CT scan was conducted to identify independent predictors for radiopacity on SWL fluoroscopy. The results were used for the creation of a predictive model. Internal validation was made on a group of 75 patients (validation group) treated from September 2012 until December 2012. Predictive accuracy of the model was evaluated by receiver operating characteristic (ROC) curve and calibration plot. The ROC curve was also used for comparing the predictive accuracy of the model to that of KUB radiography. Results: From 306 evaluated stones, 238 (77.8%) were visible on fluoroscopy. Results of the multivariate analysis revealed that stone size ( P<0.001), stone attenuation ( P<0.001), location in the midureter ( P<0.001), the distance between the stone and the anterior abdominal wall ( P<0.001), and fat thickness of the anterior abdominal wall ( P=0.001) were all independent predictors for stone radiopacity on fluoroscopy. A predictive model was produced based on the above parameters. The model demonstrated high calibration and areas under the curve of 0.923 and 0.965 in the sample and validation group, respectively, while its predictive performance was significantly higher ( P<0.001) of that of KUB radiography (area under the curve=0.727). Conclusions: This novel model can estimate with high accuracy stone radiopacity on SWL fluoroscopy using parameters of CT scan and thus it can be used as an alternative to KUB radiography for treatment planning. [ABSTRACT FROM AUTHOR]

Purpose: The goal of this study was to analyze the effect of stone composition on the efficacy of retrograde intrarenal surgery (RIRS) with kidney stones of 1-3 cm, 1-2 cm, and 2-3 cm in diameter. Methods: We undertook a retrospective analysis of 74 patients with kidney stones who underwent RIRS. The patients were divided into two groups based on stone composition: Group I ( n=47) (calcium oxalate monohydrate and calcium phosphate) was the hard to fragment stone group and group II ( n=27) (calcium oxalate dihydrate, magnesium ammonium phosphate, and uric acid) was the easy to fragment stone group. Forty-six patients with kidney stones 1 to 2 cm in diameter were divided into group A ( n=30) (smaller than 20 mm, hard to fragment stones) and group B ( n=16) (smaller than 20 mm, easy to fragment stones). Twenty-eight patients with stones 2 to 3 cm in diameter were divided into group C ( n=17) (larger than 20 mm, hard to fragment stones) and group D ( n=11) (larger than 20 mm, easy-to-crush stones). Results: The stone clearance rates of group I and group II were 66.0% and 88.9%, respectively ( P<0.05). The stone clearance rates of group A and group B were 73.3% and 100% ( P<0.05). The stone clearance rates of group C and group D were 52.9% and 72.7%, respectively. Conclusion: Stone composition has a significant impact on the efficacy of RIRS in the management of 1 to 3 cm kidney stones. For 2-3 cm calcium oxalate dihydrate stones, uric acid stones, and magnesium ammonium phosphate stones, the outcome of RIRS treatment was relatively good, and RIRS is recommended. [ABSTRACT FROM AUTHOR]

Aims and Objectives: The optimal management method of lower caliceal calculi is still undefined. We performed a prospective randomized comparison to evaluate safety and efficacy of shock wave lithotripsy (SWL) and flexible ureteroscopy (RIRS) for lower caliceal calculus ≤2 cm. Materials and Methods: Between December 2011 and January 2012, 195 patients with single radio-opaque lower caliceal calculi ≤2 cm were included in the study. Randomization was done into two groups-group A: SWL performed as an outpatient procedure using the electromagnetic lithotripter (Dornier compact delta) and group B: RIRS was performed using the 6F/7.5F flexible ureteroscope (Richard Wolf) with holmium laser intracorporeal lithotripsy. Demographic characteristics, success, retreatment, and auxiliary procedure rates and complications were analyzed statistically. Results: Of 195 patients, 97 and 98 patients were enrolled in group A and B, respectively. Mean stone size was 12.1 mm in group A vs 12.3 mm in group B ( p=0.52). The overall 3 month stone-free rate was (74/90) 82.2% for group A vs (78/90) 86.6% for group B ( p=0.34); for stones <10 mm, it was (45/55) 84.9% for group A vs (43/51) 87.7% for group B ( p=0.32) and for 10-20 mm stones, it was (29/35) 78.4% for group A vs (35/39) 85.4% for group B ( p=0.12). Retreatment rate was significantly greater in group A compared with group B (61.1% vs 11.1%; p<0.001). Auxiliary procedure rate was comparable (21.1% vs 17.7%; p=0.45). The complication rate was 6.6% in group A vs 11.1% in group B ( p=0.21). Conclusions: Both SWL and RIRS are safe and efficacious for lower caliceal calculi ≤20 mm. For stones <10 mm, SWL was less invasive and safer than RIRS with efficacy comparable to it. However, for 10-20 mm stones, RIRS was more effective, with lesser retreatment rate. [ABSTRACT FROM AUTHOR]

The article urges the Clinical Research Office of the Endourological Society (CROES) to start and lead a global research on the use of shockwave lithotripsy (SWL) as a management option in the treatment of patients with urolithiasis. Topics covered include the increasing popularity of ureteroscopy and laser lithotripsy, the pre- and post-operative variables that need to be included in a CROES database on SWL utilization, and the importance of the results of this global study in SWL.

AbstractObjectives:To evaluate the efficacy of shockwave lithotripsy (SWL) with a third-generation SWL machine in the pediatric age group and to determine the effects of stone burden and the degree of hydronephrosis on the results.Methods:Two hundred and sixty children with urinary system stones were treated with Siemens Lithostar Modularis Uro-Plus. The patients were divided into three groups according to stone burden (group 1: 200 mm2) and into four groups according to the degree of hydronephrosis (group 0: absent; group 1: mild; group 2: moderate; group 3: severe). These groups were compared in terms of the success rate of SWL.Results:Two hundred and seventy-nine renoureteral units of 260 patients were treated with 402 SWL sessions. The average stone burden was 98.2 mm2(range: 11–525). The overall success rate was 87.5%. According to stone burden, the success rate was 93.1% in group 1, 85.5% in group 2, and 60% in group 3 (p< 0.001). According to the degree of hydronephrosis, the success rate was 93.8% in group 0, 89.6% in group 1, 73.3% in group 2, and 64.3% in group 3 (p< 0.001). The average energy, number of shockwaves, number of sessions, retreatment rate, auxiliary procedure rate, and overall efficacy quotient were 1.76 units, 2260, 1.4, 33%, 8.2%, and 0.62, respectively.Conclusion:SWL is an effective treatment method in selected patients in pediatric age group. However, percutaneous nephrolithotomy can be the first alternative for stones larger than 200 mm2. It should also be kept in mind that the success rate of SWL decreases when the degree of hydronephrosis increases. [ABSTRACT FROM AUTHOR]

AbstractBackground and Purpose:This prospective, randomized, and double-blind clinical study aimed to assess the analgesic efficacy of single-dose intramuscular (IM) injection of dexketoprofen (group DE) compared with single-dose IM injection of diclofenac (group DI) in patients who were undergoing shockwave lithotripsy (SWL).Patients and Methods:A total of 70 men with single renal or ureteral stones were randomly separated into two groups. The 40 men in group DI received 75 mg IM diclofenac sodium and 30 men in Group DE received 50 mg IM dexketoprofen trometamol 30 minutes before SWL. A 10-point visual analog scale was used to evaluate pain.Results:The age, body mass index, and mean stone burden were comparable between the two groups (P> 0.05). The mean visual analog scale score for group DE was statistically lower compared with the score for group DI (P= 0.02). In 34 (85%) of the 40 men in group DI, the SWL procedure was performed with no, minor, or tolerable pain. In group DE, however, 28 (93.3%) of 30 patients evaluated the pain severity as no, minor, or tolerable (p = 0.01). No major/minor adverse effects were observed in group DI, whereas in one patient in group DE, dyspepsia after injection was noticed (P= 0.423).Conclusions:The severity of SWL-related pain was significantly better tolerated with dexketoprofen trometamol. During an SWL procedure, the analgesic efficacy of dexketoprofen was greater than that of diclofenac sodium. Although statistically insignificant, a little increased risk for gastric irritation was noticed with dexketoprofen. [ABSTRACT FROM AUTHOR]

AbstractBackground and Purpose:It is known that extracorporeal shock wave lithotripsy (SWL) may be improved by increasing cavitation using tandem shock waves. However, fluid is needed for the cavitation to work. The purpose of this research was to evaluate the importance of a fluid-filled expansion chamber in enhancing stone fragmentation during standard and tandem SWL.Materials and Methods:A piezoelectric lithotripter was modified to generate tandem shock waves. Artificial kidney stones inserted in vitrointo the parenchyma of a pig kidney were exposed to either standard or tandem shock waves. Stones in one group were placed inside a small finger cot filled with water before they were introduced into the kidney. Stone fragments were strained through a mesh, dried, and weighed.Results:Water surrounding the stones always improved stone fragmentation. The best results were achieved using tandem shock waves at a delay of 250 μs.Conclusions:A fluid-filled chamber surrounding the stone is essential for good SWL outcome. Tandem shock waves are more efficient than standard shock waves only if the stone is surrounded by fluid. [ABSTRACT FROM AUTHOR]

AbstractThe classic approach to renal stone disease includes shockwave lithotripsy, ureteroscopy or percutaneous nephrolithotripsy, and, in some cases, a combination of both. The usefulness of laparoscopy in this regard remains debated. In this report and video, we present our technique of laparoscopic pyelolithotomy assisted by flexible instrumentation to achieve maximal stone clearance in a selected group of patients. [ABSTRACT FROM AUTHOR]

AbstractPurpose:To determine the efficacy of a gated and slower shockwave lithotripsy (SWL) vsa nongated and faster SWL delivery with regard to stone fragmentation and clearance using the Medstone STS lithotriptor.Patients and Methods:We performed a retrospective chart review of 300 consecutive patients who underwent SWL for renal stones at our institution from 2001 to 2007. One hundred and five patients underwent SWL with shocks gated to the electrocardiographic signal and 195 patients underwent nongated SWL with an externally fixed signal. Subset analysis was performed between stones <1 cm and ≥1 cm. Main outcome was stone-free rates.Results:The gated procedure was performed 35% of the time. Gated and nongated patients underwent treatment at average rates of 76 shocks/minute and 120 shocks/minute, respectively. Operative time for the gated group was significantly longer at 50 minutes vs34 minutes. A significantly higher percentage of men underwent a gated procedure. Other variables for age, body mass index, American Society of Anesthesiologists class, percent lower pole, percent stented, preoperative stone burden, and mean follow-up were comparable between groups. Overall stone-free rates were comparable for gated and nongated at 33.3% and 35.4%, respectively (P= 0.819). For stones <1 cm, stone-free rates were 41.2% vs39.7% (P= 0.957) for gated and nongated groups, respectively. For stones ≥1 cm, stone-free rates were 18.9% vs26% (P= 0.520) for gated and nongated groups, respectively.Conclusions:Gated SWL requires a significantly longer time to perform and does not appear to have an affect on stone-free rates, regardless of stone size. [ABSTRACT FROM AUTHOR]

Background and PurposeMany calculi contain bacteria, which can remain active inside kidney stones and cause infection after lithotripsy. Reduction in renal infections after extracorporeal shockwave lithotripsy has been observed; however, results are controversial, and no information on the effect of shockwaves on bacteria inside kidney stones has been reported. The purpose of this research was to study whether bacteria inside kidney stones can be inactivated by shockwaves.Materials and MethodsA series of infected artificial kidney stones were exposed in vitroto either 90 or 400 shockwaves using a research electrohydraulic or a commercial piezoelectric lithotripter. Two types of stones (soft and hard) were manufactured by mixing gypsum cement and Vel-mix-stone with water. Half of the stones were inoculated with Salmonella typhimurium. The suspension containing stone powder and bacteria was inoculated on agar plates and incubated. Bactericidal action was defined as the logarithmic viability reduction.ResultsAbout 95 of the bacteria were inactivated with 400 shockwaves using the electrohydraulic lithotripter; however, most of the damage was associated with the electromagnetic emission (ultraviolet radiation and visible light) generated at the spark gap. After 2730 shockwaves to stones placed inside a black polypropylene bag, about 29 and 14 of all bacteria were inactivated with the piezoelectric and the electrohydraulic lithotripter, respectively. In this case, the electromagnetic radiation was blocked by the black bag.ConclusionsBacteria inactivation is possible by in vitroshockwave application; however, according to our results, no significant bactericidal effect is expected during extracorporeal shockwave lithotripsy. [ABSTRACT FROM AUTHOR]

IntroductionLong-term noise exposure in the workplace is a known cause of hearing loss. There has been limited study on the potential harm related to shock wave lithotripsy (SWL) or intracorporeal devices on patients and operating room personnel.Patients and MethodsWe used a digital sound meter to measure decibel levels in the operating room during several endourologic procedures. The decibel levels were recorded during SWL (Storz SLX-F2), percutaneous nephrolithotomy using single- and dual-probe ultrasonic lithotripters (Olympus LUS-2, CyberWand), and during ureteroscopy using the Versa Pulse HolmiumYAG laser. Findings were compared with the U.S. Department of Labor Occupational Health and Safety Administration and Canadian Centre for Occupational Health recommendations on permissible noise levels in the workplace.ResultsThe background sound level in the operating room prior to endourologic procedures ranged between 58 and 60 dB. In the SWL control room, 5 m from the source, the mean sound level was 68 dB (range 64–75) during treatment. The mean corresponding decibel level recorded at the patient's head during SWL was 77 dB (range 73–83). Noises produced by intracorporeal lithotripters were recorded at the surgeon's head, 2 m from the source. Measurements of the CyberWand (dual-probe) device revealed a higher mean decibel reading of 93 dB (range 85–102). Noise levels recorded for the Olympus LUS-2 (single-probe) ultrasound and the holmium laser were 65 dB (62 –68) and 60 dB (58–62), respectively.ConclusionAlthough we noted that patients and urologists maybe exposed to significant noise levels during endourologic procedures, the duration of exposure is short. This risk appears to be minimal, based on current occupational guidelines, for most operating personnel. [ABSTRACT FROM AUTHOR]

PurposeWe evaluated the effect of increased body habitus on stone-free rates after shockwave lithotripsy (SWL), determined by three reproducible skin-to-stone distances (SSDs) on CT.Patients and MethodsWe retrospectively reviewed the records of 85 patients with preoperative CT scans available on Stentor Radiology Imaging who underwent SWL with the unmodified Dornier HM3 lithotripter from 2002 to 2007. SSDs were measured at the following angles 0 degrees (vertical), 30 degrees, and 90 degrees (horizontal). Successful therapy was defined as stone free (residual fragments <2 mm) on follow-up imaging. Data were analyzed using descriptive statistics, Student t test, and the Fisher exact test.ResultsFour hundred and eighty patients underwent SWL at our institution from 2002 to 2007; 85 patients (50.6 men, mean age 50.8 ± 15.7 years, mean body mass index [BMI] 28.8 ± 6.6 kgm2) had preoperative CT scans available for review. On follow-up imaging (142.7 ± 217.2 days), 49.4 of patients were stone free. Mean SSDs (vertical, 30 degrees, horizontal) in patients who were stone-free v those with residual stone were 104.3 ± 26.2 mm v102.6 ± 29.9 mm (P 0.79), 103.9 ± 28.2 mm v101.0 ± 31.5 mm (P 0.66), and 106.6 ± 25.3 mm v107.1 ± 29.3 mm (P 0.94), respectivelyConclusionsMultiple variables have been shown to be associated with SWL success. In our sample of patients with preoperative CT scans, SSD was found to have no effect on SWL success. [ABSTRACT FROM AUTHOR]

The author offers observation on the study "In Vitro Assessment of Three Clinical Lithotripters Employing Different Shock Wave Generators" by Stuart Roy Faragher and colleagues. He praises the experimental study and emphasizes the importance of the use of artificial stones in such a study. He believes that the authors gave a better and more accurate assessment of the lithotripters' efficiency. The author outlines the important messages the study gives for both the clinicians and manufacturers.

The author discusses a research by Matlaga and others on analysis of medicare claims to compare resource utilization when either extracorporeal shockwave lithotripsy (SWL) or ureteroscopy (URS) is used as primary treatment for ureteral or kidney stones.

Purpose To study the intrarenal geometry of the lower-caliceal system in patients with and without residual fragments after extracorporeal shockwave lithotripsy (SWL) and to formulate a summarizing mathematical expression of relevant variables.Patients and Method In a series of patients consecutively treated by SWL, we analyzed the geometric anatomy in 47 patients with (group R) and 47 without (group NR) residual fragments in long-term follow-up. A number of distances and angles previously described in the literature were measured, to which was added the distance between the stone-bearing calix and the vertex of the lower renal lip (CL) and the angle (δ) this line formed with a vertical line.Results There were significant differences between the groups in terms of infundibular length (P 0.009), CL (P 0.0020), and lower-caliceal height, CH (P 0.0004). The calix width and the various angles did not differ significantly between the groups. The quotient CHCL was used to calculate cos δ, and a summarizing expression (Index LC) was given the form CH2CL which equals CH × cos δ. This index was significantly different in groups R and NR (P 0.0036). Approximately 4 of the patients in group NR, compared with 28 percent in group R, had Index LC values >25.Conclusion Index LC, as an expression of the geometry of the lower-caliceal system, might be useful for simple description of the lower-caliceal anatomy and supportive for decisions on the use of fragment clearance-facilitating procedures or the selection of a more invasive approach than SWL. [ABSTRACT FROM AUTHOR]