Lower Pole Infundibulopelvic Angle Research Articles

Assessment of Factors Responsible for Stone-Free Status After Retrograde Intrarenal Surgery.

Aim The study aimed to evaluate the predictive factors that determined stone-free rate (SFR) after retrograde intrarenal surgery (RIRS). Materials and methods This prospective study was conducted on 183 patients undergoing RIRS for renal stones. Patients were categorized into two groups, depending on stone-free status one month following the procedure. SFRwas defined as the complete absence of stones or stones <4 mm. The parameters studied included patient demographics, presence of hydronephrosis, presence of preoperative double J-stent, abnormal renal anatomy, and stone characteristics (stone burden, stone number, stone density, stone location, lower pole infundibulopelvic angle, and lower pole renal infundibular length (RIL)). Univariate and multivariate analyses were performed to identify risk factors for residual stones. We assessed the predictive ability of the RIRS score and Resorlu-Unsal stone score (RUSS) for evaluating SFR utilizing receiver operating characteristic (ROC) analysis. Results 183 patients were included inthe study with a median age of 51 years. 131 (71.6%) patients were declared stone-free after the procedure. The mean stone size and density were 16.9 SD±7.5 mm and 1038 SD±342 Hounsfield units (HU) respectively. Stone-free patients had lower stone size (14.3 mm vs. 23.6 mm, p<0.01) and stone density (970 HU vs. 1211 HU, p<0.01) compared to non-stone-free patients. Patients with residual stones had steeper lower pole renal infundibulopelvic angle (RIPA) (31.3° vs. 40.7°, p<0.01) and longer RIL(26.6 mm vs. 21.1 mm, p<0.01). Stone multiplicity (p<0.01), lower pole stone location (p<0.01), and renal malformations (p<0.01)were significant influencing factors for residual renal stones after RIRS. Multivariate analysis revealed stone size, stone density (HU), and stone location as independent predictors for SFR after RIRS. Among the scoring systems, the RIRS score had the highest diagnostic accuracy for SFR (area under the curve (AUC): -0.882, 95% CI-0.828-0.936). Conclusion Stone size, stone density (HU), and stone number are important predictors of SFR after RIRS. Lower pole stone location and abnormal renal anatomy play a substantial role in determining SFR after RIRS. In lower pole stones, a long RIL and acute RIPA negatively influence SFR. Additionally, the RIRS score was found to be a better predictor for SFR than the RUSS score.

A Retrospective Observational Study for Prediction of Stone-Free Status after Single-session of Retrograde Intrarenal Surgery for Renal Stones

Introduction: Retrograde Intrarenal Surgery (RIRS) is a preferred minimal invasive treatment modality for renal stones with advantages of being effective and having lower morbidity rates. Aim: To predict the Stone Free Rate (SFR) after RIRS with lower pole and non-lower pole stones. Materials and Methods: The records of 85 consecutive patients who underwent unilateral RIRS from September 2016 to July 2019 were retrospectively analysed. The studied parameters included patient demographics, stone characteristics (size, volume, and attenuation, Lower Pole Infundibulopelvic Angle (LP IPA) and operative time, presence of preoperative Double-J Stent (DJS) and Stone Free Status (SFS). Standard statistical tests were applied with level of significance as p&lt;0.05. Results: Overall success rate was 83.5% (71 cases) while 14 cases had Residual Stones (RS) at 1 month. The mean age of the patients was 41.07±12.25 years. The mean operative time was 68.85±22.3 minutes. Mean stone size and stone volume were higher in the RS group compared to SF (Stone free) group, 15.07±1.5 mm vs. 12.28±1.6 mm, 1187±145 mm3 vs.680.67±289 mm3 respectively (p&lt;0.001; p&lt;0.001). In RS group, 90% (13) cases had IPA&lt;45°, while 80% cases with IPA&gt;45° were stone free. Patients with non-lower pole stones has SFR 2.8 times compared to LP stones (p&lt;0.001). On multivariate analysis, only LP IPA and LP stone location predicts SFS after RIRS. Conclusion: RIRS is effective procedure for renal stones. Stone size, stone volume, LP stone location and LP IPA effectively predict SFR. However, LP IPA and LP stone location are the most significant predictor of SFS, after single session RIRS for solitary renal stone.

Influence of Lower Pole Infundibulopelvic Angle on Success of Retrograde Flexible Ureteroscopy and Laser Lithotripsy for the Treatment of Renal Stones.

Objectives: Influence of renal anatomy on success rates for shockwave lithotripsy has been reported in the literature with emphasis on lower pole anatomy. Influence of renal anatomy has not been evaluated in the setting of ureteroscopy and laser lithotripsy for stone treatment. This study analyzed the influence of infundibulopelvic angle (IPA) of the lower pole on the outcomes of ureteroscopy and laser lithotripsy with respect to stone-free rate and surgical recurrence. Materials and Methods: We retrospectively analyzed 735 renal units undergoing retrograde flexible ureteroscopy (fURS) with laser lithotripsy between January 2009 and December 2016. All cases were performed at a single institution. No exclusion criterion was applied with regard to preoperative stone location. Success was defined as no evidence of residual stone fragments on kidney, ureter, and bladder radiograph within 2 months of surgery. Failure was defined as any stone present on imaging. Lower pole IPA was measured on intraoperative retrograde pyelogram as described by Elbahanasy et al. Univariate and multivariate analyses of factors contributing to stone-free rate were performed. Secondary outcomes included surgical recurrence-free survival. Results: Of the 735 cases evaluated, 243 cases had a retrograde pyelogram stored in our Picture Archiving and Communication System (PACS) sufficient for IPA interpretation. Of these patients, 122 (50%) were women. In total, 127 patients (52.3%) were stone free on follow-up imaging, whereas 116 (47.7%) had residual stone burden. In total, 144 (59%) patients had ≤3 mm stone burden on follow-up imaging. In multivariate analysis, residual stone fragments were significantly associated with acute IPA <90° (<0.001), lower pole stones preoperatively (<0.001), and larger stone size (0.001). IPA <90° and larger stone size were both found to be statistically significantly associated with need for repeat surgery. Conclusions: Our data show that more acute IPA and larger preoperative stone size negatively affect stone-free rate and need for repeat surgery after retrograde fURS with laser lithotripsy for treatment of renal stones.

Factors affecting lower calyceal stone clearance after Extracorporeal shock wave lithotripsy

Extracorporeal 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. This 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. A 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/m 2 were stone-free, compared to 36 out of 44 patients (81.8%) with a BMI > 30 kg/m 2 . There 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.

A New Scoring System for Predicting Stone-free Rate After Retrograde Intrarenal Surgery: The “Resorlu-Unsal Stone Score”

To investigate the prognostic factors associated with the treatment efficacy of retrograde intrarenal surgery (RIRS) and develop a scoring system for predicting the stone-free rate after this surgery. We performed a retrospective analysis of 207 patients who underwent RIRS for renal stones between January 2009 and September 2011. Patient age, gender, body mass index, stone size, stone side, stone location, stone composition, number of stones, lower pole infundibulopelvic angle, using anticoagulant therapy, abnormal skeletal anatomy, and abnormal renal anatomy were investigated as potential preoperative predictive factors. The present study included 111 (53.6%) men and 96 (46.4%) women. Mean patient age was 32.9 ± 18.8 years (range 1-74) and mean stone size was 16.2 ± 4.1 mm (range 8-40). Overall, 178 of the 207 (86%) patients were stone free after the initial treatment. Univariate analysis showed that stone size (P <.001), stone location (P = .025), stone composition (P = .01), stone number (P = .049), renal malformations (P = .042), and lower pole infundibulopelvic angle (P = .003) had significant influence on the stone-free rate after RIRS. Multivariate analysis excluded stone location from the logistic regression model, whereas other factors maintained their statistically significant effect on success rate, indicating that they were independent predictors. Our study demonstrated that stone size, stone number, stone composition, infundibulopelvic angle, and renal malformations are significant predictors of RIRS outcome. A scoring system based on these factors helps separate patients into outcome groups and facilitates treatment planning.

Modified technique for difficult ureteral stenting in percutaneous nephrolithotomy via inferior calyx approach

Percutaneous nephrolithotomy (PCNL) via single inferior-calyceal tract is suitable for some partial staghorn calculi mainly located in the inferior calyx. A ureteral stent should be inserted at the end of PCNL to avoid urine leakage or ureteral obstruction by residual calculi. However, antegrade ureteral stenting via the inferior calyx is not always successful due to unfavorable lower pole calyx anatomy. In the present study, we introduced a modified method for difficult stenting. First a 0.038-inch zebra guidewire was retrogradely introduced through the previously inserted ureteral catheter and grasped out of the work sheath by a ureteroscopic forceps to develop a through-and-through guidewire; then an 8 Fr guide catheter was inserted antegradely over the guidewire into the ureter after removing the prior ureteral catheter; subsequently the zebra guidewire was removed and antegradely introduced into the bladder through the guide catheter, followed by antegrade insertion of a double J stent. Of 158 patients, 32 needed modified ureteral stenting; and the lower pole infundibulopelvic angle (LPIA) was measured in 25 patients with and in 57 patients without modified stenting. The results showed that LPIA in patients with modified stenting was much smaller than that in patients without modified stenting (56.0 ± 12.58 and 77.4 ± 11.40, P < 0.0001); when the LPIA is <60°, the modified technique should be recommended. In summary, the modified technique is simple, time-saving, less invasive and highly successful for difficult ureteral stenting in PCNL via inferior calyx.

Combination of Lower Pole Anatomic Features in A Single Infundibulopelvic Index Can Predict the Lower Pole Stone Clearance More Accurately

Purpose To investigate whether the combination of lower pole pelvicaliceal anatomic features in a single index can predict the outcome of shock wave lithotripsy treatment (SWL) of lower caliceal stones in children more accurately in stead of considering every single anatomic feature alone. Material and Methods The clinical records of children with lower caliceal stones who underwent SWL between 2002-2008 were reviewed. After excluding patients with ureteropelvic obstruction, major renal anatomic abnormalities, non-calcium stones, metabolic abnormalities, history of recurrent stone disease, multiple stones and previous renal surgery;25 paediatric patients were enrolled into study. Lower pole infundibulopelvic angle (IPA), infundibular length (IL) and width (IW) were measured from intravenous pyelography. Also, paediatric infundibulopelvic index(IPI) was calculated as [IPA( 0 )xIW(mm)x100]/[IL(mm)xstone size(mm 2 )xPelvicaliceal volume(mm 3 )]. Results The mean stone size was 72,4±49,4 mm 2 . Overall stone-free rate was %80.There were no statistically significant difference in IPA, IL and IW values between patients with residual stones and stone-free patients, respectively (p=0.06,p=0.81,p=0.21). Also no statistically significant difference were found in stone size (p=0.27),total pelvicaliceal volume(p=0.06) and SWL parameters. However IPI index was significantly different between two patient groups (p=0.04). Stone Free (mean±SD) Residual(mean±SD) P value Lower IPA( 0 ) 46,8±15,2 40±7,6 0,06 Lower IL 7,9±4 6,8±2 0,81 Lower IW 4,9±2,6 5,4±1,3 0,21 Lower IP index 0,14±0,18 0,028±0,019 0,04 Stone size 66,2±44,1 96,2±67,1 0,27 Mean number of session 1,6±0,8 1,6±0,58 0,87 Mean energy 16,9±1,2 18,3±1,1 0,06 Mean number of shockwave 2457,5±551,6 2785±786 0,33 Total pelvic volume of stone bearing kidney(range) 2621,2(582-7037) 1850(1505-17138) 0,07 Conclusions Results of this study let us think that although every single anatomic variation might have some effect on the SWL outcome of lower caliceal stones in paediatric patient basis, combination of all these anatomic parameters with the stone size in a single index could be a more accurate predictive tool because every single anatomic feature was a part of whole.

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Percutaneous nephrolithotomy for the treatment of lower pole renal calculi

Anatomic Predictors of Formation of Lower Caliceal Calculi: Is It the Time for Three-Dimensional Computed Tomography Urography?

To evaluate the various anatomic factors, using computed tomography urography (CTU), that predispose to a lower-pole kidney stone formation on one side compared with the other. The study included 51 patients with a solitary lower-pole stone. Lower-pole infundibulopelvic angle (IPA), infundibular width (IW), infundibular length (IL), caliceal volume (CV), and number of minor calices of the affected lower calyx and normal contralateral kidney were measured based on CTU. The IPA was measured according to the methods of Sampaio and Elbahnasy. A comparison was made using multivariate analysis to determine whether any of these measurements predisposed one side to form stones. The mean IPA was 80.9 degrees (Sampaio), and 52.3 degrees (Elbahnasy) on the affected kidney and 87.5 degrees (P = 0.39) and 54 degrees (P = 0.36) on the normal side. The mean IW was 2.6 mm on affected side and 3.15 mm on the normal side (P = 0.03). The mean IL was 19.7 mm and 15.3 mm (P < 0.001) on the affected and normal kidneys, respectively. Mean CV was 1123 mm(3) on affected side and 286 mm(3) on the normal side (P < 0.001). The mean number of minor calices was comparable (n = 3) on both sides with no statistical significance. Using multivariate analysis, only caliceal volume and IW sustained their significance in the final model. CTU is a very useful imaging modality in the diagnosis of intrarenal anatomic variation. Larger caliceal volume and narrower IW are associated with stone formation in lower calyx.

Significance of Lower-Pole Pelvicaliceal Anatomy on Stone Clearance after Shockwave Lithotripsy in Nonobstructive Isolated Renal Pelvic Stones

To investigate the probable effect of lower-pole pelvicaliceal anatomy on stone clearance after shockwave lithotripsy (SWL) in patients with nonobstructive renal pelvic stones. 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)). 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. 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.

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

Our aim was to evaluate the impact of pelvicaliceal variables in pediatric and adult age groups who underwent SWL for lower caliceal calculi. 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. 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 degrees and 30 degrees in pediatric group, respectively (p=0.01), whereas these values were 48.08 degrees and 43.06 degrees 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). 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.

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.

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.

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 dependant 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° and an infundibular length of <50 mm is preferable to achieve favorable outcome.