Lower Pole Kidney Stones Research Articles

Percussion, diuresis, and inversion therapy for the passage of lower pole kidney stones following shock wave lithotripsy

Lower pole kidney stones typically have poor rates of spontaneous clearance from the body. Some studies have suggested that diuresis, percussion and inversion therapy could be beneficial for people with lower pole kidney stones following shock wave lithotripsy. There is however controversy about the relative benefits, harms, and efficacy of these interventions for the management of lower pole kidney stones. To identify the benefits and harms of percussion, diuresis, and inversion therapy to facilitate the passage of lower pole kidney stones following shock wave lithotripsy. We searched the Cochrane Renal Group's specialised register up to 27 November 2013 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. All randomised controlled trials (RCTs) and quasi-RCTs looking at the benefits and harms of percussion, diuresis, and inversion therapy for aiding passage of lower pole kidney stones following shock wave lithotripsy were sought for assessment. The first phases of randomised cross-over studies were also eligible for inclusion. Two authors independently assessed study quality and extracted data. Results were expressed as relative risk (RR) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) for continuous data with 95% confidence intervals (CI). We identified two small studies (177 participants) for inclusion and analysis. One study (69 participants) compared percussion, diuresis and inversion therapy following shock wave lithotripsy versus observation-only after shock wave lithotripsy. This study reported significantly higher stone-free rates in the intervention group (RR 0.62, 95% CI 0.47 to 0.82) and a significant reduction in stone burden (MD -3.30, 95% CI -3.58 to -3.03) compared to the observation-only group. They reported no significant differences in complication rates (RR 3.00, 95% CI 0.12 to 76.24).The second study (108 participants) compared percussion, diuresis, and inversion therapy plus shock wave lithotripsy with shock wave lithotripsy therapy alone. This study reported significantly higher stone-free rates in the intervention group (RR 0.36, 95% CI 0.17 to 0.80) and a significant reduction in stone burden (MD -0.30, 95% CI -0.04 to -0.56) compared to the control group. They reported no significant differences in complication rates (RR 2.54, 95% CI 0.10 to 63.72).For both studies selection bias was unclear; there was high risk of bias for performance bias; and detection, attrition and reporting bias were low. Limited evidence from two small studies indicated that percussion, diuresis, and inversion therapy may be safe and effective therapies to assist clearance of lower pole kidney stone fragments following shock wave lithotripsy. Methodological quality in both studies was assessed as moderate. Further well-designed and adequately powered studies are required to inform clinical practice.

Flexible Ureterorenoscopy for Lower Pole Stones: Influence of the Collecting System's Anatomy

The impact of renal anatomy on the success rate of flexible ureterorenoscopy (fURS) for lower pole stones is less clear than it is on shock wave lithotripsy, for which it is a recognized influence factor. We analyzed safety and efficiency of fURS using modern endoscopes for lower pole stones dependent on the collecting system's configuration. We retrospectively evaluated a consecutive sample of 111 fURS for lower pole stones at our tertiary care center between January 2010 and September 2012 from our prospectively kept database. All procedures were performed with modern flexible ureterorenoscopes, nitinol baskets, holmium laser lithotripsy, and ureteral access sheaths whenever needed. The infundibular length (IL) and width (IW) and infundibulopelvic angle (IPA) were measured and the data were stratified for stone-free status and complications classified by the Clavien-Dindo scale. Univariate and multifactorial statistical analyses were performed. Correlation of operation time (OR-time) with anatomical parameters was conducted. Ninety-eight (88.3%) of the 111 patients were stone free after a single fURS. On multifactorial analysis, the stone size and IL had significant influence on the stone-free rate (SFR) (p<0.01), whereas IW did not. An acute IPA (<30°) also had significant influence (p=0.01). The incidence of complications and OR-time were not influenced by the pelvicaliceal anatomy. fURS is a safe and efficient treatment option for lower pole kidney stones. A long infundibulum and a very acute IPA (<30°) negatively affect the SFR. However, with second look procedures, a complete stone clearance is achievable even in case of unfavorable anatomic conditions. A narrow infundibulum has no negative effect while using modern endoscopes. The complication rate is not affected by the collecting system's anatomy.

S241 Comparison retrograde intrarenal surgey and percutaneous nephrolithotomy in obese patients with lower pole kidney stones

S241 Comparison retrograde intrarenal surgey and percutaneous nephrolithotomy in obese patients with lower pole kidney stones

Comparison of Percutaneous Nephrolithotomy, Shock Wave Lithotripsy, and Retrograde Intrarenal Surgery for Lower Pole Renal Calculi 10-20 mm

Objective: To compare the results of percutaneous nephrolithotomy (PCNL), shock wave lithotripsy (SWL), and retrograde intrarenal surgery (RIRS) for 1- to 2-cm lower pole kidney stones. Patients and Methods: This retrospective study was based on data collected from the files of patients between January 2007 and May 2012. The files of 383 patients (221 SWL, 144 PCNL, 38 RIRS) were evaluated. The groups were compared for stone size, success rate, and complication rate using the modified Clavien grading system. Results: The stone burdens of the groups were similar (p = 0.36). The success rates were 76, 94, and 73%, respectively, in SWL, PCNL, and RIRS. The highest stone-free rate was in the PNL group (p < 0.05). When the complication rates were evaluated using the Clavien grading system, they were determined to be 13% in PCNL, 3% in SWL, and 5% in RIRS. Especially GII and GIII complications were more common in the PCNL group (p < 0.05). Conclusion: PCNL seems to be the most successful but most invasive method. However, with relatively low complication rates, SWL and RIRS are other techniques to keep in mind. To determine the first-line treatment, prospective randomized studies with larger series are needed.

Efficacy of the lithotripsy in treating lower pole renal stones

Use of extracorporeal lithotripsy is declining in North America and many European countries despite international guidelines advocating it as a first-line therapy. Traditionally, lithotripsy is thought to have poor efficacy at treating lower pole renal stones. We evaluated the success rates of lithotripsy for lower pole renal stones in our unit. 50 patients with lower pole kidney stones ≤15mm treated between 3/5/11 and 19/4/12 were included in the study. Patients received lithotripsy on a fixed-site Storz Modulith SLX F2 lithotripter according to a standard protocol. Clinical success was defined as stone-free status or asymptomatic clinically insignificant residual fragments (CIRFs) ≤3mm at radiological follow-up. The mean stone size was 7.8mm. The majority of stones (66%) were between 5 and 10mm. 28% of stones were between 10 and 15mm. For solitary lower pole stones complete stone clearance was achieved in 63%. Total stone clearance including those with CIRFs was achieved in 81% of patients. As expected, for those with multiple lower pole stones the success rates were lower: complete clearance was observed in 39% and combined clearance including those with CIRFs was 56%. Overall, complete stone clearance was observed in 54% of patients and clearance with CIRFs was achieved in 72% of patients. Success rate could not be attributed to age, stone size or gender. Our outcome data for the treatment of lower pole renal stones (≤15mm) compare favourably with the literature. With this level of stone clearance, a non-invasive, outpatient-based treatment like lithotripsy should remain the first-line treatment option for lower pole stones. Ureteroscopy must prove that it is significantly better either in terms of clinical outcome or patient satisfaction to justify replacing lithotripsy.

Lower pole stones: prone PCNL versus supine PCNL in the International Cooperation in Endourology (ICE) group experience

To assess efficacy and safety of prone- and supine percutaneous nephrolithotomy (PCNL) for the treatment of lower pole kidney stones. Data from patients affected by lower pole kidney stones and treated with PCNL between December 2005 and August 2010 were collected retrospectively by seven referral centres. Variables analysed included patient demographics, clinical and surgical characteristics, stone-free rates (SFR) and complications. Statistical analysis was conducted to compare the differences for SFRs and complication rates between prone- and supine PCNL. One hundred seventeen patients underwent PCNL (mean stone size: 19.5 mm) for stones harboured only in the lower renal pole (single stone: 53.6%; multiple stones: 46.4%). A higher proportion of patients with ASA score ≥ 3 and harbouring multiple lower pole stones were treated with supine PCNL (5.8 vs. 23.1%; p = 0.0001, and 25 vs. 81.5%; p = 0.0001, respectively, for prone- and supine PCNL). One-month SFR was 88.9%; an auxiliary procedure was needed in 6 patients; the 3-month SFR was 90.2%. There were 9 post-operative major complications (7.7%). No differences were observed in terms of 1- and 3-month SFRs (90.4 vs. 87.7%; p = 0.64; 92.3 vs. 89.2%; p = 0.4) and complication rates (7.6 vs. 7.7%; p = 0.83) when comparing prone- versus supine PCNL, respectively. The results confirm the high success rate and relatively low morbidity of modern PCNL for lower pole stones, regardless the position used. Supine PCNL was more frequently offered in case of patients at higher ASA score and in case of multiple lower pole stones.

Editorial Comment

The authors of this study randomized patients with radiopaque, non–lower-pole kidney stones 5-20 mm to adjuvant tamsulosin, nifedipine, or placebo after 4000 shocks of shock wave lithotripsy (SWL) fragmentation and no ureteral stent. They defined success as kidney ureter bladder completely stone free or clinically insignificant stone fragments ≤4 mm at any time during their patients' weekly follow-ups. The authors included in their analysis any patient with at least 1 follow-up and performed an renal ultrasound at day 30 for all patients who remained in the study (82%). Overall, they found no significant difference (P = .118) in success rates among the 3 groups. By subgroup analysis, tamsulosin and nifedipine increased success rates for stones ≥10 mm (P = .024), with both drugs having higher adverse event rates compared with placebo. Overall, the study results seem valid, the patients seem to be well stratified, and the authors have taken a number of steps to decrease bias. The stone community is in sore need for these types of trials, and the authors are to be congratulated for the study completion and for their diligence. Adjuvant Tamsulosin or Nifedipine After Extracorporeal Shock Wave Lithotripsy for Renal Stones: A Double Blind, Randomized, Placebo-controlled TrialUrologyVol. 78Issue 5PreviewTo evaluate the effects of the adjuvant use of tamsulosin or nifedipine after extracorporeal shock wave lithotripsy for nonlower pole kidney stones 5-20 mm in size. Full-Text PDF ReplyUrologyVol. 78Issue 5PreviewWe appreciate and fully agree with the statements made in the Editorial Comment. We would just point out that only nifedipine was associated with significantly more side effects than placebo. Full-Text PDF

Reply

We appreciate and fully agree with the statements made in the Editorial Comment. We would just point out that only nifedipine was associated with significantly more side effects than placebo. Editorial CommentUrologyVol. 78Issue 5PreviewThe authors of this study randomized patients with radiopaque, non–lower-pole kidney stones 5-20 mm to adjuvant tamsulosin, nifedipine, or placebo after 4000 shocks of shock wave lithotripsy (SWL) fragmentation and no ureteral stent. They defined success as kidney ureter bladder completely stone free or clinically insignificant stone fragments ≤4 mm at any time during their patients' weekly follow-ups. The authors included in their analysis any patient with at least 1 follow-up and performed an renal ultrasound at day 30 for all patients who remained in the study (82%). Full-Text PDF

Acoustic radiation force applied to the treatment of lower pole kidney stones

Lower pole kidney stones have lower rates of clearance after shock wave lithotripsy or ureteroscopy compared to other stone locations. Residual stone fragments, post treatment, often lead to additional morbidity and secondary surgery. We describe the use of acoustic radiation force created by transcutaneous focused ultrasound to manipulate the location of stone fragments within the collecting system in order to facilitate their passage. Artificial and human stones were placed in the lower pole of kidneys of a porcine animal model. An open architecture, software based diagnostic ultrasound system and scanhead were modified to produce roughly 100 μs pulses of up to 16 MPa peak positive pressure in water. Stone motion was observed in real-time with simultaneous imaging through the same scanhead and with fluoroscopy. All stones were seen to move. Stone velocities were on the order of 1 cm/s. Stone displacement distance was up to 3 cm, and operators could generally control the direction of stone movement. No evidence of thermal necrosis or mechanical damage of renal tissue was observed. Thus acoustic radiation force can be used to facilitate lower pole stone fragment clearance. [Work supported by NIH DK43881, DK086371, DK092197, and NSBRI through NASA NCC 9-58.]

E29 International cooperation in endourology: Ureteral access sheath utility during flexible ureteroscopy for lower pole kidney stones

E29 International cooperation in endourology: Ureteral access sheath utility during flexible ureteroscopy for lower pole kidney stones

E107 International cooperation in endourology: Percutaneous and flexible ureteroscopic treatment of lower pole kidney stones

E107 International cooperation in endourology: Percutaneous and flexible ureteroscopic treatment of lower pole kidney stones

Prototype for expulsion of kidney stones with focused ultrasound.

Residual fragments remain in over 50% of treatments for lower pole kidney stones. A second‐generation device based on a diagnostic ultrasound system and scanhead has been developed with a unique algorithm for stone detection and the capability to focus ultrasound to expel residual fragments. Focused ultrasound was applied to a bead on string in a water tank as well as to human stones (<5 mm) implanted in the lower pole of a live porcine model via retrograde ureteroscopy. Histological samples were collected and scored in a blinded fashion for therapeutic exposures and for super‐therapeutic levels. The in‐vitro bead was visually observed to move under focused ultrasound. Even with progressive manual displacement of the bead, the system continuously tracked and caused bead movement in real time. In the live porcine model, stones were expelled from the lower pole to the ureteropelvic junction in seconds to minutes using pulses at a duty factor of 0.02 and 8 W total acoustic power. Injury was observed no more frequently than in controls. Occurrence of injury rose slightly above control at a duty factor of 0.02 and 80 W and at a duty factor of 1 and 8 W. [Work supported by NIH DK48331, NIH DK086371, and NSBRI through NASA NCC 9‐58.]

Cost‐effectiveness and efficiency of shockwave lithotripsy vs flexible ureteroscopic holmium:yttrium‐aluminium‐garnet laser lithotripsy in the treatment of lower pole renal calculi

What's known on the subject? and What does the study add? Stone management economics is a complex issue. FURS and SWL are recognised treatment option for lower pole kidney stones. There are paucity of data comparing cost implication and effectiveness of both treatment options. Both treatment modalities are equally efficacious. FURS incurred greater cost burden compared to SWL in the UK setting. In the present economic circumstance, clinicians should also consider cost-impact, patient's preference and specific clinical indication when counselling patients for treatment. • To compare the cost-effectiveness and outcome efficiency of extracorporeal shockwave lithotripsy (SWL) vs intracorporeal flexible ureteroscopic laser lithotripsy (FURS) for lower pole renal calculi ≤20 mm. • Patients who had treatment for their radio-opaque lower pole renal calculi were categorized into SWL and FURS group. • The primary outcomes compared were: clinical success, stone-free, retreatment and additional procedure rate, and perceived and actual costs. • Clinical success was defined as stone-free status or asymptomatic insignificant residual fragments <3 mm. • Perceived cost was defined as the cost of procedure alone, and the actual cost included the cost of additional procedures as well as the overhead costs to result in clinical success. • The FURS (n= 37) and SWL (n= 51) group were comparable with respect to sex, age, stone size and the presence of ureteric stent. • The final treatment success rate (100% vs 100%), stone-free rate (64.9% vs 58.8%), retreatment rate (16.2% vs 21.6%) and auxillary procedure rate (21.6% vs 7.8%) did not differ significantly. • The mean perceived cost of each FURS and SWL procedure was similar (£249 vs £292, respectively); however, when all other costs were considered, the FURS group was significantly more costly (£2602 vs £426, P= 0.000; Mann-Whitney U-test). • SWL was efficacious and cost-effective for the treatment of lower pole renal calculi ≤20 mm.

1824 INTERNATIONAL COOPERATION IN ENDOUROLOGY: PERCUTANEOUS AND FLEXIBLE URETEROSCOPIC TREATMENT OF LOWER POLE KIDNEY STONES

Introduction Lower pole kidney stones represent at time a challenge for the urologist. The gold standard treatment for intrarenal stones 2 cm is Percutaneous Nephrolithotomy (PCNL). The success rate of ESWL, however, decreases when it is employed for lower pole stones, and this is particularly true in the presence of narrow calices or acute infundibular angles. Studies have proved that ureteroscopy (URS) is an efficacious alternative to ESWL for lower pole stones <2 cm, but this is not reflected by either the European or the American guidelines. The aim of this study is to present the results of a large series of flexible ureteroscopies and PCNLs for lower pole kidney stones from high-volume centers, in order to provide more evidences on the potential indications of the flexible ureteroscopy for the treatment of kidney stones. Materials and Methods A database was created and the participating centres retrospectively entered their data relating to the percutaneous and flexible ureteroscopic management of lower pole kidney stones. Patients included were treated between January 2005 and January 2010. Variables analyzed included case load number, preoperative and postoperative imaging, stone burden, anaesthesia (general vs. spinal), type of lithotripter, access location and size, access dilation type, ureteral access sheath use, visual clarity, operative time, stone-free rate, complication rate, hospital stay, analgesic requirement and follow-up time. Stone-free rate was defined as absence of residual fragments or presence of a single fragment <2 mm in size at follow-up imaging. Primary end-point was to test the efficacy and safety of flexible URS for the treatment of lower pole stones; the same descriptive analysis was conducted for the PCNL approach, as considered the gold standard for the treatment of lower pole kidney stones. In this setting, no statistical analysis was conducted owing to the different selection criteria of the patients. Secondary end-point consisted in matching the results of stone-free rates, operative time and complications rate of flexible URS and PCNL in the subgroup of patients harbouring lower pole kidney stones between 1 and 2 cm in the higher diameter. Results A total 246 patients met the criteria for inclusion. There were 117 PCNLs (group 1) and 129 flexible URS (group 2). Ninety-six percent of cases were diagnosed by CT KUB scan. Mean stone burden was 175±160 and 50±62 mm2 for groups 1 and 2, respectively. General anaesthesia was induced in 100 % and 80% of groups 1 and 2, respectively. Pneumo-ultrasonic energy was used in 84% of cases in the PCNL group, and holmium laser in 95% of the cases in the flexible URS group. The mean operative time was 76.9±44 and 63±37 minutes for groups 1 and 2 respectively. There were 12 major complications (11%) in group 1 (mainly Grade II complications according to Clavidien classification) and no major complications in group 2. Mean hospital stay was 5.7 and 2.6 days for groups 1 and 2, respectively. Ninety-five percent of group 1 and 52% of group 2 required analgesia for a period longer than 24 hours. Intraoperative stone-free rate after a single treatment was 88.9% for group 1 and 79.1% for group 2. Overall, 6% of group 1 and 14.7% of group 2 required a second look procedure. At 3 months, stone-free rates were 90.6% and 92.2% for groups 1 and 2, respectively, as documented by follow-up CT KUB (22%) or combination of intra-venous pyelogram, regular KUB and/or kidney ultrasound (78%). In the subanalysis conducted comparing 82 vs 65 patients who underwent PCNL and flexible URS for lower pole stones between 1 and 2 cm, intreoperative stone-free rates were 88% vs 68% (p= 0.03), respectively; anyway, after an auxiliary procedure which was necessary in 6% of the cases in group 1 and 23% in group 2 (p=0.03), stone-free rates at 3 months were not statistically significant (91.5% vs 89.2%; p=0.6). Conversely, the patients undergoing PCNL maintained a higher risk of complications during the procedure, with 9 cases observed in this group versus 0 in the group of patients treated with URS (p=0.01) Conclusions These data highlight the value of flexible URS as a very effective and safe option for the treatment of kidney stones; thanks to the latest generation of flexible devices, this new technical approach seems to be a valid alternative in particular for the treatment of lower pole kidney stones less than 2 cm. In high-volume centres and in the hands of skilled surgeons, this technique can approach the stone-free rates achievable through PCNL in lower pole stones between 1 and 2 cm, with a very low risk of complications. Furthermore, the results confirm the high success rate and relatively low morbidity of modern PCNL for lower pole stones, with no difference detectable between the prone and supine position.

The Effectiveness of Shock Wave Lithotripters: A Case Matched Comparison

We compared the results of shock wave lithotripsy with a newer electromagnetic lithotripter to those of an electrohydraulic lithotripter using identical treatment and followup criteria. We performed a case matched comparison of 8,565 patients treated from 2003 to 2007 using the Medstone STS™ and the Modulith® SLX machines, matching for stone size, location and patient body mass index. The outcome of interest was treatment success in producing stone-free status. We report treatment characteristics, such as stone site and size, gating and final stone-free rate. Significance was considered at p<0.05. Overall Modulith SLX and Medstone STS stone-free rates were equivalent (61.1% and 64.5%, respectively, p=0.0664). Matching and logistic regression results showed that differences in the stone-free rate were insignificant for all stones (p>0.7592), lower pole kidney stones (p=0.9659) and ureteral stones (p=0.6409). Medstone STS performed better than Modulith SLX only for distal ureteral stones (83.63% vs 66.67%, p=0.0154). The rate of post-lithotripsy secondary procedures was equivalent (p=0.2079). The difference was insignificant for harder stones (p=0.2988). Shock wave lithotripsy is equally effective using Medstone STS and Modulith SLX for different stone sizes and most stone sites. Shock wave lithotripsy is more successful for lower ureteral stones using the Medstone STS. To our knowledge this is the first study comparing these 2 commonly used lithotripters.

5109 Brain metastases (BM) in HER2-overexpressing metastatic breast cancer (MBC): what changed in the trastuzumab therapy era? A monoinstitutional experience

To present the outcomes of flexible ureteroscopy (F-URS), shock wave lithotripsy (SWL), and observation in the management of asymptomatic lower calyceal stones.A total of 150 patients with asymptomatic lower calyceal stones were randomized into F-URS (group 1), SWL (group 2), and observation (group 3) groups. The main criteria for patient enrollment were having asymptomatic single lower pole stones <1 cm.In F-URS, the mean stone-free rate was 92% (46 of 50). The mean number of sessions for the SWL group was 1.48 ± 0.65. Stone-free rate was 90% (45 of 50). In the observation group, patients were followed up for a mean of 21.02 ± 3.65 months. Three stones passed spontaneously without any symptoms. Pain developed in 3 patients during follow-up, and 2 of them passed a stone and responded to analgesics without further treatment. Complication rates for groups 1 and 2 were similar, but group 2 had higher Clavien grades.For asymptomatic small-sized lower calyceal stones, SWL and F-URS are established treatment modalities. However, with low auxiliary treatment rates, observation may be an option for the management of nonsymptomatic small-sized lower pole kidney stones.

Evaluation of the Effects of Relationships Between Main Spatial Lower Pole Calyceal Anatomic Factors on the Success of Shock-Wave Lithotripsy in Patients with Lower Pole Kidney Stones

To evaluate the effects of lower pole calyceal anatomy on lower pole stone clearance after shock-wave lithotripsy (SWL). A total of 133 patients who had single lower pole radio-opaque stones treated with SWL alone and who became stone-free or had clinically insignificant residual fragments (CIRF) were included in the study. Pre-shock-wave lithotripsy intravenous urograms were used to determine the lower pole infundibular width and length, lower pole infundibulopelvic (LPIP) angle, caliceal pelvic height (CPH), and lower infundibular length-to-width ratio. In addition, to evaluate the relationship between LPIP and CPH, a more simple alternative measurement instead of LPIP angle, called the parenchyma-to-ureter distance (PUD), was suggested. The correlation between LPIP and PUD was then examined, and a good correlation was found between these values (P <0.000, r = 0.64). The PUD/CPH ratio was also calculated. The stone-free rate was 62%. According to the cutoff points, the lower infundibular length-to-width ratio and PUD/CPH ratio were different in the stone-free and CIRF groups by univariate analysis but not by multivariate analysis. None of the anatomic factors had a statistically significant effect in predicting the success of SWL in patients with lower pole stones. Nevertheless, evaluation of relationships between lower pole anatomic factors may offer some help in reaching a more accurate interpretation of lower pole stone clearance after SWL.

Is lower pole caliceal anatomy predictive of extracorporeal shock wave lithotripsy success for primary lower pole kidney stones?

The management of lower pole kidney stones is controversial. We examined whether lower pole caliceal anatomy could predict the success of extracorporeal shock wave lithotripsy of primary lower pole kidney stones 20 mm. or less. From December 1997 to June 2001, 246 adults with a single, 20 mm. or less radiopaque lower pole renal stone were treated with the Doli 50 lithotriptor (Dornier Medical Systems, Marietta, Georgia) while under general anesthesia. Of the 246 patients 190 (77%) had excretory urography available for review. Lower pole infundibular length and width, lower pole infundibulopelvic angle and caliceal-pelvic height were measurable on 161 (85%), 129 (68%), 128 (67%) and 163 (86%) excretory urograms, respectively. Extracorporeal shock wave lithotripsy was considered a failure if residual stone fragments remained after 1 month, or an auxiliary procedure or re-treatment was required. RESULTS The overall stone-free rate was 78% (32 of 41) for stones 5 mm. or less, 73% (98 of 135) for stones 6 to 10 mm., 43% (22 of 51) for stones 11 to 15 mm. and 30% (7 of 19) for stones 16 to 20 mm. in maximum linear dimension. The stone-free rates grouped according to stone surface area were 76% (48 of 63 stones) for stone surface area 25 mm.2 or less, 69% (97 of 141) for 26 to 100 mm.2 and 33% (14 of 42) for 101 to 400 mm.2. Caliceal anatomy was not predictive of success even with stones grouped as 10 or less or 11 to 20 mm. Grouping patients with favorable (lower pole infundibulopelvic angle 70 degrees or greater, lower pole infundibular length 30 mm. or less and lower pole infundibular width greater than 5 mm.) versus unfavorable (70 degrees or less, greater than 30 mm. and 5 mm. or less, respectively) anatomy was also not predictive of success. On the Doli 50 machine stone size rather than caliceal anatomy is predictive of treatment outcome. Initial treatment failures with this machine should be managed by alternative endoscopic procedures if necessary rather than by repeat shock wave lithotripsy.

Shock wave lithotripsy success determined by skin-to-stone distance on computed tomography

Objectives To evaluate whether the skin-to-stone distance (SSD), body mass index (BMI), and Hounsfield unit (HU) density can be used as independent predictors of stone-free (SF) status after shock wave lithotripsy (SWL) of lower pole kidney stones. No studies have evaluated the SSD by non-contrast-enhanced computed tomography (NCCT) as a predictor of SWL success. Studies have suggested that the BMI and HU density of urinary calculi on NCCT may predict the SF rate after SWL. Methods The radiographs of 64 patients treated with SWL (DoliS lithotripter) from March 2000 to April 2004 with lower pole kidney stones measuring 0.5 to 1.5 cm on NCCT were reviewed. The average SSD was calculated by measuring three distances from the center of the stone to the skin (0°, 45°, and 90° angles) on NCCT. The BMI and HU density were determined, and chemical analysis was performed on all stones. Radiographic assessment of the kidneys, ureter, and bladder at 6 weeks categorized patients into the SF or residual stone group. Logistic regression was fit, using SSD, BMI, and HU density as predictors, to assess the SF rates after SWL. Results Of 64 patients, 30 were SF and 34 had residual stones. The mean SSD was 8.12 ± 1.74 cm for the SF group versus 11.53 ± 1.89 cm for the residual stone group ( P <0.01). Logistic regression analysis revealed only SSD to be a significant predictor of outcome (odds ratio 0.32, 95% confidence interval 0.29 to 0.35, P <0.01). An SSD greater than 10 cm predicted treatment failure. Conclusions The SSD may predict the outcome after SWL of lower pole kidney stones. SWL in patients with an SSD greater than 10 cm is likely to fail. The use of the SSD may be transferable to the treatment of all urinary stones, regardless of location.

Impact of Lower Pole Anatomy on Stone Clearance After Shock Wave Lithotripsy

This study retrospectively analyzed patients treated with shock wave ithotripsy (SWL) for lower calyceal stones, to determine the influence of the lower pole anatomy and stone size in predicting the clearance of fragments. Between June 2000 and March 2002, we reviewed excretory urography (IVU) of 59 patients with isolated lower pole stones treated with SWL. A total of 44 men and 15 women, with an age ranging between 23 and 78 years (mean, 55 years), were included in the study. The patients were divided into two groups, either a stone-free group or residual-stone group. After SWL, overall stone rate was 57.6%, and clearance for stones less than 10 mm in diameter was 64.5%, whereas clearance was 50% for stones between 10 and 20 mm in diameter. Intrarenal anatomy on IVU, such as infundibular width and infundibulopelvi-ureteric angle showed no significant difference between the stone-free and residual-stone groups. Our analysis showed that three significant variables were relevant to stone clearance: infundibular length, stone size and stone burden. We conclude that SWL is the best treatment for lower pole kidney stones 10 mm or less in diameter, showing lower complication and acceptable stone-free rates.