Caliceal Stones Research Articles

Percutaneous Nephrolithotomy: Variables That Influence Hemorrhage

Renal hemorrhage is one of the most common and worrisome complications of percutaneous nephrolithotomy (PCNL). This study attempted to identify variables that might influence hemorrhage during PCNL to help urologists establish preventative and treatment strategies for bleeding during PCNL procedures. The data of 193 patients (193 PCNL procedures) were retrospectively analyzed. Hemorrhage was estimated by the postoperative decrease in hematocrit factored by the quantity of any blood transfusion. Various preoperative and operative factors were assessed for their association with blood loss using univariate, forward multivariate regression and correlation analysis. The mean patient age was 45.7 +/- 14.4 years (range 5 to 74). The overall stone-free rate was 85.4%. The average hematocrit decrease was 8.7% +/- 5.39% (range 0.3 to 24.7). Forward multivariate regression analysis identified five significant variables that influenced PCNL-related hemorrhage: stone type (P = 0.003), number of tracts (P = 0.010), method of dilation (P = 0.010), diabetes (P = 0.022), and stone surface area (P = 0.049). A statistically significant difference was found in relation to the occurrence of hemorrhage between patients with caliceal stones and partial staghorn stones (P = 0.008) and complete staghorn stones (P = 0.006), single tracts and multiple tracts (P = 0.038), balloon dilators and Amplatz dilators (P = 0.007), patients with small stones (1000 mm2 or smaller) and large stones (greater than 1000 mm2; P = 0.018) on univariate analysis. Also, the stone surface area (P = 0.019) and number of tracts (P = 0.024) showed a positive correlation with the mean hematocrit decrease. Staghorn stones, multiple tracts, the presence of diabetes, and large stones were associated with increased renal hemorrhage during PCNL on multivariate analysis. However, balloon dilation was associated with decreased hemorrhage.

Tubeless percutaneous nephrolithotomy in selected patients: a prospective randomized comparison

To prospectively compare the outcome of standard and tubeless percutaneous nephrolithotomy (PNL) in a selected group of patients with renal stones. Patients with simple, isolated renal pelvis or lower pole caliceal stones and no significant hydronephrosis were randomly enrolled to undergo either standard PNL, in which routine nephrostomy tube was placed at the end of operation, or tubeless PNL. Occurrence of intraoperative complications, total operative time exceeding 2 h, indication for additional access or second-look PNL due to residual stones were exclusion criteria. There were 11 isolated lower pole caliceal stones (mean stone burden: 3.1 cm(2)) and 6 isolated renal pelvis stones (mean stone burden: 2.8 cm(2)) in the tubeless PNL group (n: 17), and 9 isolated lower pole caliceal stones (mean stone burden: 3.4 cm(2)) and 9 isolated renal pelvis stones (mean stone burden: 3.1 cm(2)) in the standard PNL group (n: 18). Mean operation time was 59.6 +/- 9.1 (range: 50-90) min in the tubeless group, and 67.3 +/- 10.1 (range: 60-115) min in the standard PNL group (P > 0.05). Successful stone removal was achieved in all patients, and no significant complication was observed in any case. The mean postoperative analgesic requirement was significantly less in the tubeless group (P < 0.05). Mean hospital stay was 1.6 +/- 0.4 (range: 1-3) days in the tubeless group, and 2.8 +/- 0.9 (range: 2-4) days in the former group (P < 0.05). Our results indicate that tubeless PNL is safe in the management of selected patients and that mean analgesic requirement as well as hospitalization time is diminished with this modification.

Acute Effects of Percutaneous Tract Dilation on Renal Function and Structure

Percutaneous nephrolithotomy (PCNL) is performed on a routine basis for the rapid and efficient removal of large caliceal stones. After percutaneous puncture, rigid dilators or an inflatable balloon are used to dilate the nephrostomy tract to allow access to the collecting system for stone removal. Little is known of the acute impact of tract dilation procedures on renal function. We compared renal hemodynamic and excretory function in female pigs immediately before and up to 5 hours after percutaneous nephrostomy (PCN) using sequential Amplatz dilators (N = 8) or Nephromax balloon inflation (N = 7) and control pigs with no PCN access (N = 8). We also examined renal function in patients undergoing PCNL. The two PCN procedures produced a renal lesion of comparable size and morphology, as well as similar changes in renal function. Glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion (U(Na)V) were significantly reduced in Amplatz- and Nephromax-treated kidneys throughout the 5-hour observation period, by about 50%, 60%, and 80%, respectively. In control pigs, GFR and RPF remained stable and U(Na)V declined progressively to about 50% of baseline over the course of the experiment. The contralateral kidney showed changes in renal function similar to those in the PCN-treated or control kidney in all three groups. A retrospective analysis of 196 adults with normal renal function who underwent unilateral PCNL using the Nephromax balloon dilator revealed a significant increase in serum creatinine of 0.14 mg/dL at 1 day. Both animal and human studies show that PCN is associated with an acute decline in renal function.

Impact of Percutaneous Access Point Number and Location on Complication and Success Rates in Percutaneous Nephrolithotomy

Objectives: Percutaneous nephrolithotomy (PNL) is sometimes associated with complications, especially in patients with complex stones. Herein, we review our experience with PNL to determine the impact of percutaneous access number and location on success and complication rates. Patients and Methods: During a 2-year period, a total of 275 patients with a mean age of 42.3 ± 14.8 (range: 13–75) years underwent PNL. Stones were classified as simple in 51.6%, and complex (staghorn calculi or renal pelvis stones coexisting with caliceal stones) in 48.4%. Percutaneous access was done under C-armed fluoroscopy and the tract was formed with a high-pressure balloon dilation system. One single percutaneous access was sufficient in 210 (76.4%), while 2 accesses were utilized in 44 (16%), and ≧3 accesses in 21 cases (7.6%). Supracostal access was performed in 23 (8.4%) patients. Results: An overall success rate of 94.9% was achieved. Stone location, but not the access point location, was the major determinant for success, which was 99.3 and 90.2% in patients with simple and complex stones, respectively (p < 0.01). Significant complications included bleeding necessitating blood transfusion in 28 (10.2%), and hydropneumothorax in 2 (0.7%) patients. Bleeding was observed in 39.1 and 7.5% of patients managed with supracostal access, and subcostal access, respectively (p < 0.01). An increased number of access points significantly augmented the risk for bleeding. Bleeding was encountered in 7.6% of patients managed with 1 percutaneous access point, and in 18.5% of cases managed with ≧2 access points (p < 0.05). Hydropneumothorax occurred in patients with supracostal access. Conclusion: Supracostal access as well as multiple punctures may be needed especially in the management of complex stones, and the need for multiple access points and supracostal access significantly increases complication rates.

V-02.05: Second-look flexible nephroscopy for restant caliceal stones

Access to all caliceal groups through a single percutaneous traject is difficult, if not impossible using the rigid nephroscopes. This study aimed to evaluate the efficiency of flexible nephroscopy during the second-look procedures for restant caliceal stones following percutaneous rigid approach.

Preoperative Nomograms for Predicting Stone-Free Rate After Extracorporeal Shock Wave Lithotripsy

Extracorporeal shock wave lithotripsy is currently accepted as a first line treatment modality for urolithiasis. In obtaining informed consent it is important to inform patients of the stone-free rate with extracorporeal shock wave lithotripsy before surgery. The present study was performed to develop preoperative nomograms for predicting stone-free rates after extracorporeal shock wave lithotripsy. A total of 435 patients with 507 urinary stones were treated with extracorporeal shock wave lithotripsy with a Dornier Lithotripter D. Patient age, sex, body mass index, number of stone(s) in each treatment, stone length, side and location were evaluated before extracorporeal shock wave lithotripsy, and treatment efficacies were evaluated at 3 months after each session. The treated stones were divided into 2 groups, those in cases that were stone-free with a single extracorporeal shock wave lithotripsy session and those in all other cases. Multivariate analysis was performed using a logistic regression model. The nomograms were developed by repeating the analysis on 200 bootstrap samples. Stone length, location and number were identified as significant variables on multivariate analysis, and a logistic regression model was developed using these variables. The nomograms predicting stone-free rate at 3 months after single extracorporeal shock wave lithotripsy treatment were finally developed from 200 bootstrap samples. In these nomograms the stone-free probability was highest for solitary proximal ureteral stones less than 5 mm in size (93.8%) and lowest for multiple caliceal stones greater than 21 mm (10.5%). This study demonstrated that stone size, location and number are significant predictors of extracorporeal shock wave lithotripsy outcome. We have developed nomograms for predicting the stone-free rate of extracorporeal shock wave lithotripsy, which is useful for counseling patients with urolithiasis before surgery.

Can Phyllanthus niruri Affect the Efficacy of Extracorporeal Shock Wave Lithotripsy for Renal Stones? A Randomized, Prospective, Long-Term Study

Phyllanthus niruri is a plant used in Brazilian folk medicine for the treatment of urolithiasis. We assessed the efficacy of P. niruri after extracorporeal shock wave lithotripsy for renal stones. We prospectively evaluated 150 patients with renal stones that were as large as 25 mm and composed of calcium oxalate. All patients received 1 to 3 extracorporeal shock wave lithotripsy sessions by Dornier Lithotriptor S. After treatment 78 of 150 patients (52%) underwent therapy with Uriston, a P. niruri extract (2 gm daily) for at least 3 months (group 1). Otherwise 72 of 150 patients (48%) were used as a control group (group 2). No significant difference in stone size between the 2 groups was found. Stone clearance was assessed after 30, 60, 90 and 180 days by abdominal x-ray and ultrasound scan. Stone-free rate (stone-free defined as the absence of any stone or residual fragments less than 3 mm) was 93.5% in group 1 and 83.3% in group 2 (p = 0.48) at the end point of the followup (180 days). For lower caliceal stones (56 patients) the stone-free rate was 93.7% in the treatment group and 70.8% in the control group (p = 0.01). Re-treatment need for group 1 was 39.7% and for group 2 it was 43.3% (p = 0.2). No side effects were recorded with extracorporeal shock wave lithotripsy or P. niruri therapy. Regular self-administration of P. niruri after extracorporeal shock wave lithotripsy for renal stones results in an increased stone-free rate that appears statistically significant for lower caliceal location. Its efficacy and the absolute lack of side effects make this therapy suitable to improve overall outcomes after extracorporeal shock wave lithotripsy for lower pole stones.

Is pelvicaliceal anatomy a risk factor for stone formation in patients with solitary upper caliceal stone?

Objectives To investigate the effect of pelvicaliceal anatomy on stone formation in patients with solitary upper caliceal stones. Methods The records of patients with solitary upper caliceal stones between 1996 and 2004 were reviewed. After the exclusion of patients with hydronephrosis, major anatomic abnormalities, noncalcium stones, metabolic abnormalities, history of recurrent stone disease, multiple stones, and previous renal surgery, 42 patients (24 male, 18 female) and 42 healthy subjects (22 male, 20 female) with normal results on intravenous pyelography (IVP) were enrolled into the study. With a previously described formula, upper pole infundibulopelvic angle (IPA), infundibular length (IL) and width (IW), and pelvicaliceal volume of the stone-bearing and contralateral normal kidney of patients and bilateral normal kidneys of healthy subjects were measured from IVP. Results Forty-two stone-bearing and 126 normal kidneys (42 contralateral, 84 healthy) were assessed. The mean stone size was 153.47 mm 2 (range, 20 to 896 mm 2). There were no statistically significant differences in terms of upper caliceal specifications between stone-bearing and normal kidneys. The mean (± standard deviation) pelvicaliceal volume of 42 stone-bearing and 126 normal kidneys was 2455.2 ± 1380.2 mm 3 and 1845.7 ± 1454.8 mm 3, respectively ( P = 0.019). These values were 2114 ± 2081.5 mm 3 ( P = 0.34) and 1709.5 ± 989.1 mm 3 ( P = 0.001) for contralateral normal kidneys (n = 42) and normal kidneys of healthy subjects (n = 84), respectively. Conclusions Explanation of the etiology of the upper caliceal stone by the anatomic features is very difficult, and these caliceal anatomic variables (IPA, IL, IW) seem not to be a significant risk factor for stone formation in the upper calyx.

The impact of pelvicaliceal anatomical variation between the stone-bearing and normal contralateral kidney on stone formation in adult patients with lower caliceal stones

We aimed to investigate the effect of pelvicaliceal anatomical differences on the etiology of lower caliceal stones. Records of adult patients between January 1996 and December 2005 with solitary lower caliceal stone were reviewed. After exclusion of patients with hydronephrosis, major renal anatomic anomalies, non-calcium stones, history of recurrent stone disease and previous renal surgery, 78 patients were enrolled into the study. Lower pole infundibulopelvic angle (IPA), infundibulovertebral angle (IVA), infundibular length (IL), width (IW), number of minor calices and cortical thickness of the lower pole together with other caliceal variables obtained from the whole pelvicaliceal anatomy of both stone-bearing and contralateral normal kidneys were measured from intravenous pyelogram of the patients. Total pelvicaliceal volume was also calculated by a previously described formula for both kidneys. There were statistically significant difference between two kidneys in terms of IW (p < 0.001) and IL (p = 0.002) of the upper calyx, IW (p = 0.001) and IVA (p < 0.001) of the lower calyx), pelvicaliceal volume (p < 0.001), IPA of middle calyx (p = 0.006) and cortical thickness over the lower pole (p < 0.001). However there was no difference between stone-bearing and contralateral normal kidneys in terms of lower pole IPA (p = 0.864) and IL (p = 0.568). Pelvicaliceal volume but not lower caliceal properties seem to be a risk factor for stone formation in lower calyx.

Lower-Caliceal Stone Clearance Index to Predict Clearance of Stone after SWL

There is no uniform consensus regarding the anatomic factors that influence the clearance rate of caliceal stones after SWL, as different authors have studied various independent factors separately. We correlated both favorable and unfavorable factors into a formula to predict the clearance rate. A series of 56 consecutive patients (37 male, 19 female) with isolated lower-caliceal single stones (right 29, left 27) treated with SWL using the Dornier Compact Delta lithotripter were analyzed retrospectively. Of these, 40 patients had soft stones, and 16 patients had hard stones. The first stone-free rate (SFR) according to plain films and ultrasonography was analyzed by stone size, and a stone clearance index (SCI) formula was applied to see if there was any change in the SFR, especially for stones >2 cm. The formula, which correlated well with the clearance, is SCI = [(IVA x IW x stone type)/IH] - (stone size in mm(2)/10). Nearly all (90%) of the patients with an SCI of >0 cleared their stones within 3 months, and 87% of the patients with an SCI <0 cleared their stones after 3 months. Positive and negative predictive values were 93.33% and 76.9%, respectively. The accuracy of the correlation is 85.71%. The success of SWL for lower-caliceal stones can be predicted easily using the SCI. Stones of >200 mm(2) (>2 cm) surface area may still be suitable for SWL if the SCI is positive, whereas alternative treatment modalities should be considered if the SCI is a low negative value (<-7).

Factors affecting the success rate of extracorporeal shock wave lithotripsy for renal calculi in children

The aim of the study was to analyse factors affecting the success rate of extracorporeal shock wave lithotripsy (ESWL) in children with renal calculi. We performed a retrospective analysis reviewing records of 85 (40 female, 45 male) children (89 renal units) subjected to ESWL for treatment of renal calculi during 1990-2005 in our department. As 4 patients had bilateral calculi and 19 children (21 renal units) had renal stones at more than one different site, each location was analysed separately for convenience. The mean age of the patients was 10.3+/-4.6 (2-16) years. The stone-free rates for renal pelvis, lower, middle and upper caliceal calculi were 70, 62, 50 and 73%, respectively. A higher rate (33%) of insignificant fragments (< or = 4 mm) was noted for lower pole calculi. Increased stone diameter (P=0.0001) and burden (P=0.04) were found as the most significant factors that adversely affect the stone-free rate for pelvis renalis calculi, whereas an acutely oriented infundibulum and/or a long lower infundibulum (P=0.005) were unfavourable factors for clearance of lower caliceal stones. The stone-free rate in children with multiple calculi was 48%, while 29% of the renal units had retained fragments. ESWL is a good initial option for treatment of most of the renal calculi < 2 cm except in the presence of unfavourable lower caliceal anatomy. Increased stone burden, multiple stones, staghorn calculi, narrow lower infundibulopelvic angle and long lower infundibulum are factors that adversely affect the clearance rate.

Editorial comment

This important communication by Demirkesen et al. answers several questions regarding pediatric stone treatment, but also raises interesting questions. In their study, the authors found that ESWL was equally effective for stones in all locations, although the stone burdens were less for lower pole caliceal stones compared with renal pelvic stones. The communication supports the use of ESWL, as opposed to percutaneous stone removal, for stones less than 2 cm. This conclusion, however, lacks certain information that makes it difficult to translate to other practices. First, no stone analysis was available. Second, no comparison was made among the types of commercially available lithotriptors, which may have marked differences in efficacy. Third, the infundibulopelvic angle, infundibular length, and infundibular width may also be strong determinants of stone passage. 1 Elbahnasy A.M. Clayman R.V. Shalhav A.L. et al. Lower-pole caliceal stone clearance after shockwave lithotripsy, percutaneous nephrolithotomy, and flexible ureteroscopy impact of radiographic spatial anatomy. J Endourol. 1998; 12: 113-119 Crossref PubMed Scopus (107) Google Scholar The conclusions in this paper leave me somewhat satiated, but still eager for further information on which to feast. Additional studies are needed to determine the efficacy of pediatric ESWL according to stone composition, lithotripter type, and pelvicaliceal anatomy. The development of such a nomogram would truly be an advance in the treatment of urolithiasis. Efficacy of extracorporeal shock wave lithotripsy for isolated lower caliceal stones in children compared with stones in other renal locationsUrologyVol. 67Issue 1PreviewTo evaluate the efficacy of extracorporeal shock wave lithotripsy (ESWL) monotherapy for isolated lower caliceal calculi in a pediatric age group and compare it with that for isolated middle/upper caliceal and renal pelvic calculi. Full-Text PDF

Efficacy of extracorporeal shock wave lithotripsy for isolated lower caliceal stones in children compared with stones in other renal locations

Objectives To evaluate the efficacy of extracorporeal shock wave lithotripsy (ESWL) monotherapy for isolated lower caliceal calculi in a pediatric age group and compare it with that for isolated middle/upper caliceal and renal pelvic calculi. Methods We retrospectively reviewed the data of 151 renal units in 126 children treated with ESWL for isolated caliceal and renal pelvic stones from March 1992 to February 2004. The stones were localized in the lower, middle/upper calices, and renal pelvis in 50, 26, and 75 renal units, respectively. The results were compared with respect to renal location and stone burden. Results The median patient age was 8 years (range 1 to 16). The median stone burden in the lower and middle/upper caliceal groups was significantly lower than in the renal pelvis group at 0.6, 0.6, and 1 cm 2, respectively ( P = 0.002). The overall stone-free rate was 62% for lower calices, 65.3% for middle/upper calices, and 80% for renal pelvis stones. For the group with a stone size greater than 2 cm 2, the stone-free rate decreased to 33% in both lower and middle/upper calices; however, it was almost the same in the renal pelvis (81.8%). A highly significant relation was found between the stone burden and number of sessions ( P <0.001), but none between the stone burden and stone-free rate. Conclusions In our study, ESWL was equally effective for stones in all locations. We recommend ESWL as the primary treatment of choice for stones less than 2.0 cm 2 in all caliceal locations. For the management of caliceal stones greater than 2.0 cm 2, prospective randomized trials comparing ESWL and percutaneous nephrolithotomy are necessary.

Pelvicaliceal Anatomical Variation Between Stone Bearing and Normal Contralateral Kidneys???Does it Have an Impact on Stone Formation in Pediatric Patients With a Solitary Lower Caliceal Stone?

Pelvicaliceal Anatomical Variation Between Stone Bearing and Normal Contralateral Kidneys???Does it Have an Impact on Stone Formation in Pediatric Patients With a Solitary Lower Caliceal Stone?

Pelvicaliceal Anatomical Variation Between Stone Bearing and Normal Contralateral Kidneys—Does it Have an Impact on Stone Formation in Pediatric Patients With a Solitary Lower Caliceal Stone?

We aimed to investigate the probable effect of pelvicaliceal anatomical differences between stone bearing and normal contralateral kidneys on the etiology of stone formation in children with a solitary lower pole caliceal stone. We reviewed the clinical records of 25 pediatric patients who underwent SWL for a solitary lower caliceal stone and 15 healthy pediatric patients who served as controls. Lower pole IPA, IL and IW, together with other caliceal variables obtained from the pelvicaliceal anatomy of the stone bearing and contralateral normal kidneys of patients with urolithiasis, and both kidneys of the control group were measured based on excretory urography. Also, total pelvicaliceal volume for both kidneys was calculated. Mean LIPAs of stone bearing kidneys compared to the normal contralateral kidneys was more acute, equal and wider in 52%, 16% and 32% of the patients, respectively. Mean pelvicaliceal volumes of the stone forming and normal kidneys were 1,553.8 mm(3) (range 242 to 7,107) and 581.0 mm(3) (90 to 2,662), respectively, and there was statistical significance only in pelvicaliceal volumes between the stone bearing and contralateral normal kidneys (p <0.001). Our results reveal that IPA, IL and IW of calices do not have an effect on stone formation in pediatric patients. However, large pelvicaliceal volume seems to be a significant risk factor for stone formation in the lower calix, probably because it creates abnormal urodynamic and morphological features, especially when accompanied by other metabolic abnormalities.

The coagulum pyelolithotomy.

Abstract Coagulum pyelolithotomy is mainly indicated in cases of multiple stones, soft and crumbly stone or stones, small, mobile caliceal stones, and as an aid to fixing caliceal stone or stones in the calix prior to partial resection of the kidney or nephrolithotomy. Its main advantages are:— Trauma to the kidney is minimized.All the free stones in the pelvicaliceal system may be removed, thus reducing the incidence of so-called ‘recurrent’ stones.Fragmentation of the stone during removal is avoided.Surgical mobilization of the kidney is not necessary since it is sufficient to expose the pelvis. A method of coagulum pyelolithotomy is described in detail and discussed. The operation has been performed in 22 cases with good results. Two cases are described in detail. It is suggested that this method could be utilized for common bile-duct stones.

Radiographic anatomical factors do not predict clearance of lower caliceal calculus by shock-wave lithotripsy

Use of shock-wave lithotripsy (SWL) for lower caliceal calculus is associated with a relatively high rate of residual fragments. Various radiographic anatomical factors of the lower calix predicting the outcome of lithotripsy have been described and have generated considerable discussion. We aimed to reassess the role of these factors in predicting clearance of lower caliceal stones by SWL. Between January 1998 and December 2001, 148 patients underwent SWL for solitary lower caliceal stones using a Dornier Compact S lithotripter. The infundibular length, infundibular width, caliceopelvic height and infundibulopelvic angle were measured. Success was defined as either complete clearance or clearance with insignificant residual fragments <4 mm in size at 3 months follow-up. The results were analysed using the chi2 test and logistic regression analysis. Complete clearance was seen in 69% of cases and clearance with residual fragments <4 mm in size at 3 months was seen in 5%. The overall clearance rate at 3 months was 74%. Infundibular length, infundibular width, caliceopelvic height and stone size were not found to be statistically significant in predicting clearance. None of the patients had an infundibulopelvic angle of >90 degrees. Contrary to most previous studies, univariate and multivariate analysis revealed that an infundibulopelvic angle of <70 degrees was statistically significant in predicting clearance in the stone-free group. The use of radiographic anatomical factors to predict clearance of lower caliceal stones following SWL is an attractive concept. However, based on this study, we feel that these factors do not merit the attention they have attracted. In routine practice, regardless of the radiological anatomy, SWL continues to be the initial treatment option, given its non-invasive nature and ease of administration.

Extracorporeal shock wave lithotripsy in the treatment of renal pelvicalyceal stones in morbidly obese patients

Management of urolithiasis in morbidly obese patients is usually associated with higher morbidity and mortality compared to non-obese patients. In morbidly obese patients, since the kidney and stone are at a considerable distance from the skin (compared to non-obese patients) difficulty may be found in positioning the patient so that the stone is situated at the focal point of the lithotripter. To evaluate the outcomes and cost-efficiency of extracorporeal shock wave lithotripsy (ESWL) in the treatment of renal pelvicalyceal stones sized between 6 and 20 mm in morbidly obese patients. Using various aids, such as mobile overtable module, extended shock pathway and abdominal compression 37 patients with body mass index more than 40 kg/m2 were treated using the Siemens Lithostar-plus third generation lithotripter. The size of renal pelvicalyceal stones was between 6 and 20 mm. Treatment costs for shock wave lithotripsy were calculated. The overall stone free rate at 3 months of 73% was achieved. The mean number of treatments per patient was 2.1. The post-lithotripsy secondary procedures rate was 5.4%. No complications, such as subcapsular haematoma or acute pyelonephritis were recorded. The most effective (87% success rate) and cost-efficient treatment was in the patients with pelvic stones. The treatment of the patients with low caliceal stones was effective in 60% only. The cost of the treatment of the patients with low calyceal stones was in 1.8 times higher than in the patients with pelvic stones. We conclude that ESWL with the Siemens Lithostar-plus is the most effective and cost-efficient in morbidly obese patients with pelvic stones sized between 6 and 20 mm. 87% success rate was achieved. The increased distance from the skin surface to the stone in those patients does not decrease the success rate provided the stone is positioned in the focal point or within 3 cm of it on the extended shock pathway. ESWL should not be considered as the first line of treatment in the morbidly obese patients with low caliceal stones where the stone was positioned more than 1 cm from the focal point on the extended shock pathway.

169Is the difference of stone clearance after shockwave lithotripsy for lower caliceal stones between adult and paediatric age groups influenced by the difference of lower caliceal anatomical variations?

169Is the difference of stone clearance after shockwave lithotripsy for lower caliceal stones between adult and paediatric age groups influenced by the difference of lower caliceal anatomical variations?

Giant abdominal wall abscess dissecting into thorax as a complication of ESWL

Abscess as a complication of extracorporeal shock wave lithotripsy is a rare condition. We present the computed tomography findings of an abdominal wall abscess that occurred after extracorporeal shock wave lithotripsy for which prophylactic antibiotics had not been given. The abscess destroyed the posterior abdominal wall muscles and dissected into the thorax. The muscles were thickened and showed enhancement. A parenchymal defect in the right kidney adjacent to a caliceal stone, with strands extending from this defective region to the abscess, was observed, and was thought to be the result of parenchymal destruction caused by the shock waves. Other parts of the kidney and psoas muscle were normal. Microbiologic examination revealed Escherichia coli.