Lower pole ratio: A new and accurate predictor of lower pole stone clearance after shockwave lithotripsy?

BACKGROUND: Lower pole spatial anatomy is an important determinant of success after extracorporeal shockwave lithotripsy. In the present study, we determine whether there is a significant relationship between lower pole ratio (infundibular length : infundibular width) on preoperative intravenous urograms and stone fragment clearances after shockwave lithotripsy. METHODS: A total of 42 patients with isolated lower pole stones were retrospectively reviewed. Anatomical factors, such as infundibular length, width and infundibulopelvic angle were measured and the lower pole ratio was calculated on pretreatment intravenous urogram. Stone fragment clearance was assessed at three months with a plain abdominal X-ray. RESULTS: The overall three-month stone-free rate was 62%. Mean stone size +/- SD was 10 +/- 4.8 mm, mean infundibular length was 21.7 +/- 6.9 mm, mean infundibular width was 6.1 +/- 2.3 mm, mean infundibulopelvic angle was 62.1 +/- 30.1 degrees and mean lower pole ratio was 4.3 +/- 2.8. Stone-free status after shockwave lithotripsy was significantly related to infundibular length and width as well as to lower pole ratio, but not to infundibulo-pelvic angle. Infundibular length less than 30 mm, width greater than 5 mm and lower pole ratio less than 3.5 were noted to have an improved three-month stone-free rate (P = 0.049, 0.01 and <0.01, respectively). CONCLUSION: Caliceal anatomy is an important consideration for lower pole stone clearance after shockwave lithotripsy. The present study suggests that a lower pole ratio of less than 3.5, which considers both infundibular length and width, is a promising predictor for stone-free status.     

Impact of lower pole renal anatomy on stone clearance after shock wave lithotripsy: fact or fiction?

PURPOSE: We determined whether there is a significant relationship between the spatial anatomy of the lower pole on preoperative excretory urography and stone fragment clearance after shock wave lithotripsy. MATERIALS AND METHODS: The anatomical factors affecting lower pole stone clearance after shock wave lithotripsy were evaluated retrospectively in 108 patients. Stone-free status was assessed by renal computerized tomography with or without renal ultrasound. The stone-free rate at 3 months was correlated with lower pole infundibular length and width in mm. as well as with the lower pole infundibulopelvic angle in degrees. The statistical significance of each lower pole anatomical factor as well as other stone, renal and treatment factors were correlated with the stone-free rate using the Mann-Whitney and chi-square tests. RESULTS: Three months after shock wave lithotripsy 79 patients (73.1%) were free of stones. Mean lower infundibular length plus or minus standard deviation was 20.9 +/- 6.56 mm., mean infundibular width was 5.65 +/- 2.34 mm. and the mean lower pole infundibulopelvic angle was 48.33 +/- 14.84 degrees. In 49 (45.4%) and 59 (54.6%) patients infundibular length was greater than 3 cm. and 3 cm. or less, respectively. Infundibular width was greater than 5 mm. and 5 mm. or less in 45 (41.7%) and 63 (58.3%) patients, respectively. No obtuse infundibulopelvic angles were noted. None of the 3 lower pole anatomical factors had any significant impact on the stone-free rate at 3 months. Renal morphology was the only factor significantly affecting the stone-free rate since stone clearance was significantly less in pyelonephritic kidneys (p = 0.0009). CONCLUSIONS: Differences in the intrarenal anatomy of the lower pole have no significant impact on stone clearance after shock wave lithotripsy. Further examination of the lower pole renal anatomy with a search for other contributing factors is still warranted.     

Infundibulopelvic anatomy and clearance of inferior caliceal calculi with shock wave lithotripsy

PURPOSE: We evaluate the significance of inferior caliceal radiographic anatomy and determine its influence on successful fragmentation and clearance of inferior caliceal calculi with extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: Between November 1996 and February 1998, 88 patients and 90 renal units with single or multiple inferior caliceal calculi of all sizes and composition were treated with ESWL. The size, number and area of calculi, length and width of the stone bearing inferior calix and infundibulopelvic angle were determined on pretreatment excretory urography. The infundibulopelvic angle was measured by 2 methods using the angle between the inferior caliceal infundibular and ureteral axes (angle 1), and between the infundibular and ureteropelvic axes (angle 2). Cases with residual fragments not clearing within 6 months of satisfactory fragmentation after lithotripsy were considered failures. RESULTS: Overall stone clearance at 6 months was achieved in about 72% of the renal units. Infundibular length was 30 mm. or less in 77% of successful cases and in 64% of failures. Similarly, the smallest infundibular width of 5 mm. or more was found in 75% of successful cases compared to 41% of failures. Angle 1 of 35 degrees or more was observed in 73% of cases with compared to 18% without clearance. Angle 2 of 45 degrees or more was seen in 71% of successful cases compared to 9% of failures. The chances of a patient becoming stone-free with all favorable criteria of infundibular length 30 mm. or less, infundibular width 5 mm. or greater and infundibular ureteropelvic angle 45 degrees or greater was 100% (23 patients). CONCLUSIONS: Radiographic features of a stone bearing inferior calix and its relation to the renal pelvis can be easily measured on standard excretory urography. An infundibular width of 5 mm. or more and infundibulopelvic angle 1 of 35 degrees or more or angle 2 of 45 degrees or more were statistically significant factors of radiographic anatomy in stone clearance following ESWL. Inferior caliceal length was not statistically significant, although length of 30 mm. or less appeared to be more favorable for stone clearance. The ideal treatment of inferior caliceal calculi in patients with all 3 favorable criteria is ESWL.     

Impact of anatomical pielocaliceal topography in the treatment of renal lower calyces stones with extracorporeal shock wave lithotripsy

AIM: There is wide consensus that the lowest success rate of extracorporeal shock wave lithotripsy (ESWL) is in the complete clearance of renal stones located in the lower calyces. We assess the effectiveness of extracorporeal shock wave lithotripsy monotherapy for lower pole renal calculi to determine the relationship between the spatial anatomy of lower pole and the outcome of ESWL. METHODS: We evaluated 107 patients who were treated for solitary lower pole renal stones less than 20 mm in diameter with ESWL. The spatial anatomy of the lower pole, as defined by the lower infundibulopelvic angle, infundibular length and infundibular width, was measured by preoperative intravenous pyelography, while the stone location and size were determined by using abdominal plain X-ray. All patients were followed up at 1 and 3 months with abdominal plain X-ray and ultrasonography. RESULTS: Only 62 patients (58%) became stone free, while 45 (42%) retained residual fragments. A small lower infundibulopelvic angle, a long infundibular length and a tight infundibular width are unfavorable for stone clearance after ESWL. CONCLUSIONS: ESWL is the treatment of choice for most renal and ureteral stones. However, stone clearance from the lower pole following ESWL is poor and significantly affected by the inferior pole collecting system anatomy. Therefore, we believe it is important to evaluate these anatomical factors when deciding on the best treatment for lower pole renal calculi.     

Usefulness of lower ihfundibular length-to-diameter ratio as a predictor of lower pole stone clearance after extracorporeal shock wave lithotripsy; clinical research with two lithotriptors

PURPOSE: Lower pole renal stones are well known to exhibit a poor stone clearance rate following extracorporeal shock wave lithotripsy (ESWL). In the present study, we analyzed several anatomical factors as predictors of lower pole stone clearance that may be used to indicate the usefulness and the universality of ESWL in such patients with two different lithotriptors. PATIENTS AND METHODS: 93 patients with a unilateral single lower pole stone of 2 cm. or less underwent ESWL using Piezolith 2500 or Medstone STS, were included in the study. An IVP was used to determine the lower infundibulopelvic angle, the caliceal pelvic height, the lower infundibular length, the lower infundibular diameter, the lower infundibular length-to-diameter ratio and the number of lower pole minor calyces. Stone-free status was assessed by a plain film with or without renal ultrasound. RESULTS: The stone clearance rate at the Piezolith 2500 group was 53.1% (34 of 64 patients), while was 51.7% (15 of 29 patients) at the Medstone STS group. In all cases, the overall stone clearance rate was 52.7% (49 of 93 patients). Age, laterality of the stone burden within the kidney and stone size were not different between the stone-free and residual stone groups. Multivariate logistic analysis revealed that length-to-diameter ratio was the most independent predictors of successful stone clearance at each group. The patients exhibited length-to-diameter ratio less than 7 achieved high stone clearance rates, greater than 72%. In contrast, the stone clearance rate was less than one third when length-to-diameter ratio was 7 or greater. Besides length-to-diameter ratio was strong prognostic factor in patients with stones 1 cm. or less and 1 to 2 cm at each group. CONCLUSION: From this study, it is apparent that successful ESWL is highly sensitive to the anatomy of the lower pole of the kidney. Especially, the lower infundibular length-to-diameter ratio is potentially useful and a universal predictor regardless of the kind of lithotriptors at least in patients with a lower pole radiopaque stone 2 cm. or less treated with ESWL.     

Is the gravity effect of radiographic anatomic features enough to justify stone clearance or fragments retention following extracorporeal shock wave lithotripsy (SWL)

We determined whether the gravity effect of radiographic anatomic features on the preoperative urography (IVP) are enough to predict fragments clearance after shock wave lithotripsy (SWL). A Total of 282 patients with mean age 45.8 ± 13.2 years (189 male, 93 female), who underwent SWL due to renal calculi between October 2005 and August 2009 were enrolled. The mean calculi load was 155.72 ± 127.66 mm2. The patients were stratified into three groups: patients with pelvis calculi (group 1); patients with upper or middle pole calculi (group 2) and patients with lower pole calculi (group 3). Three angles on the pretreatment IVP were measured: the inner angle between the axis of the lower pole infundibular and ureteropelvic axis (angle I); the inner angle between the lower pole infundibular axis and main axis of pelvis-ureteropelvic (UP) junction point (angle II) and the inner angle between the lower pole infundibular axis and perpendicular line (angle III). Multivariate analysis was used to define the significant predictors of stone clearance. The overall success rate was 85.81%. All angles, sessions number, shock waves number and stone burden were significant predictors of success in patients in group 1. However, in group 2 only angle II and in group 3 angles I and II had significant effect on stone clearance. Radiographic anatomic features have significant role in determining the stone-free rate following satisfactory fragmentation of renal stones with SWL. The measurement of infundibulopelvic angle in different manner helps to predict the stone-free status in patients with renal calculi located not only in lower pole, but also in renal pelvis and upper or middle pole. Gravity effect is not enough to justify the significant influence of the radiographic anatomic features on the stone clearance and fragments retention after SWL.     

The impact of radiological anatomy in clearance of lower caliceal stones after shock wave lithotripsy

The goal of this study was to determine the factors affecting stone clearance after extracorporeal shock wave lithotripsy (ESWL) for lower caliceal stones. Lower pole stone clearance was investigated in 128 (80 males, 48 females) patients treated with ESWL during 1998–2003 in our clinic. Renal anatomy was determined on standard intravenous urogram. The lower infundibulopelvic angle (LIPA) was measured as the angle between the vertical pelvis axis and the vertical axis of lower infundibulum (Sampaio’s method). The mean age of the patients was 42.8 ± 12.4 (19–77) years. The mean stone diameter and burden were found to be 1.28 ± 0.58 (0.5–3.5) cm and 1.2 ± 1 (0–7) cm² respectively. The stone-free rate was 62.5% and ESWL was unsuccessful in 16 (12.5%) patients. Thirty-two (25%) patients had residual fragments ≤4 mm retained in lower calices after lithotripsy. The stone clearance was found to be unrelated to stone burden and diameter (P = 0.17 and P = 0.14, respectively). However, there was a significant difference between mean lower pole infundibulum length (P = 0.001), infundibulum width (P = 0.001) and LIPA (P = 0.0001) between stone-free patients and patients with residual fragments. Multivariate logistic regression analysis accepting stone-free as the favourable result also confirmed that LIPA, lower pole infundibulum length and width were factors that significantly affected the outcome. Lower pole anatomy has a significant influence on clearance of fragments after ESWL.     

The impact of caliceal pelvic anatomy on stone clearance after shock wave lithotripsy for pediatric lower pole stones

PURPOSE: The clearance rather than stone disintegration of lower pole stones after shock wave lithotripsy (SWL) is significantly inferior according to the other localizations of the kidney. We retrospectively evaluated the impact of caliceal pelvic anatomy on stone clearance after SWL for pediatric lower pole stones. MATERIALS AND METHODS: We treated 163 renal units (RUs) in children 16 years old or younger with SWL between March 1992 and February 2002. In 36 RUs stones were localized in the lower calices. All patients were treated with sedoanalgesia except 3 (8%) who were treated under general anesthesia. Patients were evaluated by excretory urography and ultrasonography 12 weeks after the last session, and were designated as stone-free or with residual stone. The lower infundibular length, width, length-to-width ratio, pelvic caliceal height and lower infundibulopelvic angle were determined on standard excretory urography before SWL. All measurements were done by 1 urologist who was unaware of the results. Statistical analysis was performed with chi-square, Fisher's exact and Mann-Whitney U tests. ROC analysis was done to determine the cutoff points of caliceal anatomy measurements for stone clearance. RESULTS: We treated 36 RUs in 23 males and 10 females with isolated lower caliceal stones. Median patient age was 10.5 years (range 2 to 16). Median stone burden was 0.7 cm (range 0.2 to 4), and median number of shock waves and energy used for the entire patient population was 1,500 and 17.2 kV, respectively. Overall stone-free rates for the 36 RUs were 61% after a median treatment session of 1 (range 1 to 7) and retreatment rates were 39%. Of the patients rendered free of stones 13 (59%) were treated in a single SWL session and 9 (41%) underwent 2 or more sessions. Median lower infundibular length, width, length-to-width ratio and pelvic caliceal height in the stone-free and residual stone group were 25.5, 28.0 mm, 4.5, 5.0 mm, 6.4, 5.5 mm and 21.5, 21.5 mm, respectively (p = 0.810, 0.327, 0.511 and 0.511). Median lower infundibulopelvic angle in the stone-free and residual stone groups was 92.50 and 92.50 degrees, and 60.0 and 54.50 degrees, respectively (p = 0.860 and 0.089). On ROC analysis no parameter predicting stone-free rate and cutoff points of caliceal anatomy measurements for stone clearance was found. CONCLUSIONS: Our results suggest that caliceal pelvic anatomy in pediatric lower pole stones has no significant impact on stone clearance after SWL. There was a highly significant relation between retreatment rates and stone burden, which should be considered for determining the treatment modality.     

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

OBJECTIVE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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 of Lower Calyx Calculi: How Much Is Treatment Outcome Influenced by the Anatomy of the Collecting System?

OBJECTIVES: Extracorporeal shock wave lithotripsy (ESWL) of lower calyx stones has been criticized because of the high incidence of residual fragments. Controversial results have been reported regarding the stone-free rate after ESWL depending on the influence of the collecting system anatomy on stone clearance. Therefore we evaluated our stone-free rate after ESWL of lower calyx stones and searched for correlations to various anatomic parameters of the collecting system. METHODS: Ninety-six patients with isolated lower calyx stones treated exclusively with ESWL (Dornier HM3) were evaluated 3 mo postoperatively. The results were correlated with the following anatomic parameters of the collecting system as determined from the pretreatment intravenous urography: (1) lower infundibulum width, (2) lower infundibulum length, (3) infundibulopelvic angle, (4) volume of the collecting system. Follow-ups were performed 24 h after ESWL with an abdominal plain film and 3 mo postoperatively with a urography or abdominal plain X-ray together with renal ultrasound. RESULTS: Three months postoperatively, 68% of all patients were stone free, including 69% of the patients with stones initially < or =1 cm, and 67% of the patients with stones >1 cm. Stone-free patients compared with patients having residual fragments had no significant differences in infundibulum width, infundibulum length, infundibulopelvic angle, or collecting system volume. CONCLUSIONS: A stone-free rate 3 mo after ESWL of 68% overall justifies ESWL as a possible treatment option for lower calyx stones. Influence of the collecting system anatomy on disintegrate clearance from the lower calyx could not be demonstrated.     

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

PURPOSE: 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. MATERIALS AND METHODS: 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. CONCLUSIONS: 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.     

The impact of radiological anatomy in clearance of lower calyceal stones after shock wave lithotripsy in paediatric patients

OBJECTIVE: To determine the factors affecting stone clearance after extracorporeal shock wave lithotripsy (ESWL) in children with lower calyceal stones. MATERIALS AND METHODS: Lower pole stone clearance was reviewed in 34 patients aged between 2 and 16 years (23 boys and 11 girls) treated with ESWL between 1989 and 2001 in our clinic. Renal anatomy was determined on standard intravenous urograms. The lower infundibulopelvic angle (IPA) was measured by two different methods based either on measuring the angle between vertical pelvis axis and vertical axis of lower infundibulum or finding the angle between the ureteropelvic axis and vertical axis of lower infundibulum. RESULTS: The mean age of the patients was 12.1+/-4.16 (2-16) years. The mean stone burden was found as 96.93+/-87.13 mm(2) and the mean shock wave number per session and power as 2631.4+/-593.1 and 17.57+/-1.1 kV, respectively. The stone-free rate was 55.9%. Fifteen (44.1%) cases had residual fragments retained in lower calices after lithotripsy and are still followed. The stone clearance was found to be unrelated to stone burden and infundibulum width (p=0.44 and p=0.34, respectively). However, a significant difference was present between mean lower pole infundibular length (p=0.0032) and lower IPA measurements according to both methods between stone-free cases and others. The most remarkable factor that had a significant influence on stone clearance was an acutely oriented infundibulum defined according to IPA-ureteropelvic axis angle determination method (p=0.00001) followed by Sampaio's pelvic axis method (p=0.0001). Only 1 (5%) patient was stone-free under 40 degrees and 1 (6%) case with an angle of 45 degrees had residual fragments in the former method. Similarly none of the cases had residual fragments over 90 degrees for Sampaio's method and 90% of the stone-free cases had a more obtuse angle. Thus, we determined that a cut-off point of 40 degrees for the IPA-ureteropelvic axis method and 90 degrees for Sampaio's method was most useful to determine the clearance of lower pole fragments. CONCLUSION: The factors affecting stone clearance in paediatric patients are similar to adults.     

Factors affecting lower calyceal stone clearance after Extracorporeal shock wave lithotripsy

ObjectiveExtracorporeal shock wave lithotripsy (ESWL) is one of the most commonly used procedures to remove renal calculi from the lower calyces. The aim of this work is to study the impact of radiological, anatomical and demographic factors on stone clearance after ESWL of lower calyceal calculi.Patients and methodsThis retrospective study included 150 patients aged between 16 and 70 years who were subjected to ESWL at October 6 University Hospital, Egypt, between June 2008 and October 2011. All the patients had solitary radio-opaque lower calyceal renal stones sized 2 cm or less. Intravenous urography (IVU) was performed to determine the patients’ lower-pole calyceal anatomy (infundibulum width, infundibulum length and the lower-pole infundibulopelvic angle). The patients who were divided into two groups according to the treatment results (Group 1: stone-free patients; Group 2: patients with residual fragments) were followed up for 3 months and re-assessed by plain X-ray.ResultsA total of 126 patients (84%) were stone-free (Group 1), while 24 patients (16%) had residual fragments (Group 2). The stone size was 0.5–1 cm in 76 patients (60.3%) and 1–2 cm in 50 patients (39.7%) of Group 1, respectively, with no statistically significant difference. In patients with a lower-pole infundibulopelvic angle ≥45°, stone clearance was 52% compared to a stone clearance of 32% in patients with a lower-pole infundibulopelvic angle <45° with no statistically significant difference. Regarding the infundibulum length (<35 mm vs. ≥35 mm) and width (<4 mm vs. ≥4 mm), no statistically significant difference was observed between Group 1 and Group 2. Ninety out of 106 patients (84.9%) with a body-mass index (BMI) ≤30 kg/m² were stone-free, compared to 36 out of 44 patients (81.8%) with a BMI > 30 kg/m².ConclusionsThere is no statistically significant effect of stone size, anatomy of the lower calyx and BMI on stone clearance after ESWL of lower calyceal stones. However, small stone size (≤2 cm), a shorter and wider infundibulum and a larger lower-pole infundibulopelvic angle seem to promote a more rapid and more complete stone clearance.     

Clearance of lower-pole stones following shock wave lithotripsy: effect of the infundibulopelvic angle.

OBJECTIVE: To assess the effect of anatomic factors, especially the angle of the lower-pole infundibulum, on stone clearance following shock wave lithotripsy (SWL) in order to determine selection criteria for percutaneous nephrolithotomy. METHODS: We retrospectively analyzed 116 patients with single lower-pole stones measuring 11-20 mm treated with SWL. Intravenous urograms were reviewed to measure the infundibulopelvic angle, the angle of the infundibulum to the vertical, and the anatomy of lower-pole calyces. RESULTS: The overall stone-free rate was 52%. Factors most closely associated with a stone-free status were obtuse infundibulopelvic angle, lack of calyceal distortion, and a large infundibular diameter. The infundibulopelvic angle was the only factor to attain significance in predicting stone-free status (p = 0.012). The size of the stone did not predict eventual stone-free status (p = 0.911), but larger stones were more likely to require intervention after SWL. CONCLUSION: For solitary lower-pole stones 11-20 mm in size, the angle of the lower-pole infundibulum as it relates to the pelvis plays a role in eventual stone clearance and should be taken into account before choosing a mode of treatment.     

Efficacy of extracorporeal shock wave lithotripsy for solitary lower calyceal stone: a statistical model

OBJECTIVE: To evaluate the effect of inferior calyceal radiographic anatomy, number of extracorporeal shock wave lithotripsy (ESWL) sessions and stone size on the successful clearance of solitary inferior calyceal calculi after ESWL. PATIENTS AND METHODS: In a prospective study between January 2001 and November 2002, 66 renal units with a solitary inferior calyceal calculus of < or = 2 cm were treated with electrohydraulic ESWL. The infundibulopelvic angle (two definitions), infundibulovertebral angle, inferior calyceal infundibular diameter, infundibular length, cortical thickness over the lower pole, number of minor calyces and stone size were determined from intravenous urography before treatment. The number of ESWL sessions was also included in the analysis. Treatments which produced residual fragments not clearing within 3 months of satisfactory fragmentation were considered as failures. All patients in whom the treatment failed were treated successfully by percutaneous nephrolithotomy. The data were then analysed using two different statistical methods; first by intravariable differences using the test of proportion (Fisher's test) and then all the variables together using logistic regression. RESULTS: At 3 months 78.8% of the renal units were clear of stone. All intravariable differences were statistically significant except stone size (<1 cm, 1-2 cm). In a multivariate analysis of all variables, only stone size was the most important predictor for successful stone clearance (P = 0.03). CONCLUSIONS: ESWL is the initial treatment of choice in selected patients with inferior calyceal stones. The stone size appears to be the most important predictor for stone clearance.     

Is stone clearance after shockwave lithotripsy in patients with solitary upper-caliceal stone influenced by anatomic differences in the pelvicaliceal system?

PURPOSE: We investigated the effect of pelvicaliceal differences on stone clearance after extracorporeal shockwave lithotripsy (SWL) in patients with solitary upper-caliceal stones. PATIENTS AND METHODS: The clinical records of patients with solitary upper-caliceal stones who underwent SWL between 1996 and 2004 were reviewed. After excluding patients with hydronephrosis, significant anatomic abnormalities, non-calcium stones, metabolic abnormalities, recurrent stone disease, multiple stones, and previous renal surgery, 42 patients with a mean stone size of 153.47 mm2 (range 20-896 mm2) were enrolled in this study. They were divided into three groups according to stone burden (group 1 < or =100 mm2, group 2,101 mm2-200 mm2, and group 3 >200 mm2). Upper-pole infundibulopelvic angle (IPA), infundibular length (IL), and infundibular width (IW) were measured from intravenous urograms. Results: Of the total, 29 patients (69%) were stone free after SWL treatment. The differences in the upperpole IPA, IL, and IW of stone-free patients and patients with residual stones were not statistically significant (P = 0.85, P = 0.89, and P = 0.37, respectively). Again, there were no statistically significant differences in terms of upper IPA, IW, and IL in comparing the three groups divided by initial stone size. Conclusion: Upper-caliceal anatomy does not exert a significant impact on stone clearance after SWL for isolated upper-caliceal stones. To best of our knowledge, this is the first study to investigate the effects of pelvicaliceal anatomy on SWL treatment for upper-caliceal stones, so there is a need for further investigations to confirm our findings.     

The impact of pelvicaliceal features on problematic lower pole stone clearance in different age groups

Aim Our aim was to evaluate the impact of pelvicaliceal variables in pediatric and adult age groups who underwent SWL for lower caliceal calculi. Methods 25 pediatric and 78 adult patients treated with extracorporeal shock wave lithotripsy (SWL) between 1996 and 2004 were enrolled into the study after exclusion of patients with hydronephrosis, major renal anatomic anomalies, non-calcium stones, history of recurrent stone disease and previous renal surgery. Lower pole infundibulopelvic angle (IPA), infundibular length (IL), infundibular width (IW) and pelvicaliceal volume were measured from pre-SWL intravenous urography. The pelvicaliceal stone load (PSL) index implicating the stone burden of each patient described as the relationship between stone volume and total estimated pelvicaliceal volume for stone-bearing kidney was also calculated. Results Sixty-eight percent of adult and 80% of pediatric patients became stone-free after SWL. The statistical insignificance between PSL index (p = 0.097) of two groups shows that both groups shared a similar stone burden. According to SWL outcome, mean IPA values of stone-free and residual patients were 46.85° and 30° in pediatric group, respectively (p = 0.01), whereas these values were 48.08° and 43.06° in the adult group, respectively (p = 0.352). In the pediatric age group, stone-free and cumulative success rates increased with increasing IPA but this correlation was statistically insignificant (p: 0.263). Conclusions Lower caliceal anatomy has a higher impact on stone clearance after SWL in pediatric patients and urologists can expect better SWL outcomes from pediatric population with solitary lower caliceal stone than adults under the same conditions.     

Predictive factors of lower calyceal stone clearance after Extracorporeal Shockwave Lithotripsy (ESWL): a focus on the infundibulopelvic anatomy

INTRODUCTION: Controversy exists as to whether ESWL is suitable for lower pole renal stones, given the dependent position of the lower calyces. This study aims to test the effect of lower pole anatomy, namely lower polar infundibulo-pelvic angle, infundibular length and width, on clearance of fragments after ESWL. PATIENTS AND METHODS: We conducted a retrospective study of 205 renal units with single lower pole stones of not more than 25 mm in their greatest diameter that were treated by ESWL alone. Exclusion criteria included multiple stones, patients requiring stenting or percutaneous drainage for various reasons. Pretreatment IVU was used to measure lower polar dimensions. Post treatment ultrasonography and KUB were used to assess clearance of fragments. RESULTS: The right kidney was involved in 68% and the left in 42% of cases. Average number of sessions was 1.6 with an average 3277 shockwaves per session. 134 patients (65.3%) required one session, 41 requiring 2 sessions (20%), 18 requiring 3 sessions (8.7%), 6 requiring 4 sessions (2.9%) and 8 requiring 5 sessions (3.9%). Complete clearance was attained in 141 cases, while 64 cases had residual fragments, 20 were asymptomatic and required no further management. The lower pole infundibulo-pelvic angle (LIP-A) was the most significant factor in clearance (p value 0.00001). Infundibular length (IL) was also statistically significant (p value 0.039). CONCLUSION: Lower pole anatomy has a significant impact on ESWL results. LIP-A not less than 70 degrees and an infundibular length of < 50 mm is preferable to achieve favorable outcome.     

Is there a simpler method for predicting lower pole stone clearance after shockwave lithotripsy than measuring infundibulopelvic angle?

BACKGROUND AND PURPOSE: Several anatomic factors influence the clearance of lower pole stones treated with shockwave lithotripsy (SWL). One of these is the infundibulopelvic angle, but its measurement is complex. METHODS: We proposed a more simple measure of caliceal dependence, the caliceal pelvic height (CPH), which we defined as the distance between a horizontal line from the lowermost point of the calix containing the stone to the highest point of the lower lip of the renal pelvis. RESULTS: In 62 patients who had SWL for solitary lower pole stones, a CPH < 15 mm was associated with a stone clearance rate of 92%, whereas with a CPH > or = 15 mm, the clearance rate was only 52% (p < 0.05). A majority (74%) of the patients with an infundibular width of > or = 5 mm were rendered stone free compared with 40% of those with a width of < 5 mm (p < 0.05). CONCLUSION: Measurement of the CPH, in conjunction with other anatomic factors, may more accurately predict the outcome of SWL in patients with lower pole stones.     

Significance of lower-pole pelvicaliceal anatomy on stone clearance after shockwave lithotripsy in nonobstructive isolated renal pelvic stones

PURPOSE: To investigate the probable effect of lower-pole pelvicaliceal anatomy on stone clearance after shockwave lithotripsy (SWL) in patients with nonobstructive renal pelvic stones. PATIENTS AND METHODS: The clinical records of patients with isolated renal pelvic stones who underwent SWL between 1996 and 2005 were reviewed. After excluding patients with obstruction leading to dilatation, major anatomic abnormalities, noncalcium stones, metabolic abnormalities, history of recurrent stone disease, multiple stones, and previous renal surgery, 153 patients were enrolled in the study. Lower pole infundibulopelvic angle (IPA) and infundibular length and width were measured from intravenous urography. Patients were classified into three groups according to stone burden (group 1, <100 mm(2); group 2, 101-200 mm(2); group 3, 201-400 mm(2)). RESULTS: The mean stone size was 142.08+/-86.3 mm(2). Overall stone-free rate was 53.6%. Localization of clinically significant or insignificant residual fragments was in the lower calix, renal pelvis, and both in 50 (32.6%), 29 (18.9%), and 8 (5.2%) patients, respectively. There was no statistically significant difference in pelvicaliceal anatomic features except narrower IPA (P=0.02) in group 1 patients with residual stones. CONCLUSION: The falling of stone fragments to the lower calix in spite of the ureter whether clinically significant or not after SWL of pelvic stones initially seems to be related to stone burden rather than lower caliceal anatomy. However, existence of a more narrow IPA in group 1 patients with residual fragments led us to believe that lower-pole IPA can play a role in stone clearance, especially for smaller stones, probably because of smaller residual fragment size or the more mobile nature of the primary stone.