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

A temperature model for laser lithotripsy

Objective

To derive and validate a mathematical model to predict laser-induced temperature changes in a kidney during kidney stone treatment.

Methods

A simplified mathematical model to predict temperature change in the kidney for any given renal volume, irrigation flow rate, irrigation fluid temperature, and laser power was derived. We validated our model with matched in vitro experiments.

Results

Excellent agreement between the mathematical model predictions and laboratory data was obtained.

Conclusion

The model obviates the need for repeated experimental validation. The model predicts scenarios where risk of renal tissue damage is high. With real-time knowledge of flow rate, irrigating fluid temperature and laser usage, safety warning levels could be predicted. Meanwhile, clinicians should be aware of the potential risk from thermal injury and take measures to reduce the risk, such as using room temperature irrigation fluid and judicious laser use.

The influence of pelvicalyceal system anatomy on minimally invasive treatments of patients with renal calculi

INTRODUCTION AND OBJECTIVES

Nephrolithiasis has a multifactorial etiology, wherein, besides metabolic factors, the anatomy of the pelvicalyceal system might play a role. Using 3D-reconstructions of CT-urography (CT-U), we studied the morphometric properties of pelvicalyceal anatomy affecting kidney stone formation and compared those with existing literature on their effect on minimally invasive treatment techniques for renal calculi.

METHODS

CT-U's were made between 01-01-2017 and 30-09-2018. Patients were chronologically included in two groups: a nephrolithiasis group when ≥ 1 calculus was present on the CT-U and a control group of patients with both the absence of calculi on the CT-U and no medical history of urolithiasis. Patients with a medical history of diseases leading to higher risks on urolithiasis were excluded. In the nephrolithiasis group affected kidneys were measured. In the control group, left and right kidneys were alternately measured.

RESULTS

Twenty kidneys were measured in both groups. Mean calyceopelvic tract width was significantly larger in the lower segments of affected kidneys (3.9 vs. 2.7 mm). No significant differences between the groups were found in number of calyces, infundibular length, infundibular width, calyceopelvic angle, upper-lower angle and diameters of the pelvis. Transversal calyceal orientation in hours was significantly smaller in the upper and lower segments of the nephrolithiasis group (7.69 vs. 8.52 and 8.08 vs. 9.09 h), corresponding with more dorsally located calyces in stone-forming kidneys.

CONCLUSION

Pelvicalyceal anatomy differs between stone-forming and non-stone-forming kidneys. Understanding the pelvicalyceal system and etiology of stone formation can improve development of endourological techniques.

The anatomy of the renal pyelocaliceal system studied by CTU

INTRODUCTION AND OBJECTIVES

Knowledge of the pyelocaliceal system anatomy is essential for the safe and successful performance of endourologic procedures. The purpose of this study was to provide a better understanding of the full three-dimensional pyelocaliceal system anatomy.

METHODS

Morphometric parameters of the three-dimensional reconstructions of computed tomography intravenous urography scans (n = 25 scans) were analyzed. Both kidneys were divided into three equal-sized segments (US: upper segment, MS: mid segment, LS: lower segment). Infundibular length (IL), infundibular width (IW), the number of calyces, and the transverse orientation in hours of a clock of each calyx as well as the dimension of the pyelum were determined.

RESULTS

The mean upper IL (n = 92) was longer than the middle (n = 154) and lower IL (n = 112) (30.6 ± 7.9 mm vs. 16.4 ± 7.7 mm vs. 16.0 ± 6.0 mm, respectively; P = < 0.0001). IW was significantly smaller in the MS [3.7 ± 1.9 mm], followed by the US [4.6 ± 1.9 mm], and the LS [4.9 ± 2.2] in the increasing order. No correlation was found between IL and IW (Pearson correlation coefficient = 0.1). The US calyces were predominantly orientated lateral (8-10 o'clock: 44.5%) and medial (2-4 o'clock: 30.5%), in the MS lateral (8-10 o'clock: 87.6%) and anterolateral in the LS (9-12 o'clock: 67.9%). 74% of the kidneys consisted of 6-8 calyces (mean 7.2 ± 1.4, range 4-10), with the majority of the calyces in the MS (3.1 ± 0.8) followed by the LS (2.24 ± 0.8), and US (1.8 ± 0.7). There were no statistical differences between the right and left kidneys in terms of IL (P = 0.112) and number of calyces (P = 0.685).

CONCLUSION

Anatomic differences between the three segments of the pyelocaliceal system in terms of IL, IW, calyces number, and orientation are seen and should be considered when performing an endourologic procedure.

Revisiting the morphology of pelvicalyceal system in human cadaveric kidneys with a systematic review of literature

Objective

Renal collecting system macroscopically consists of minor calyx, major calyx, renal pelvis and ureter. Stone in renal collecting system is a common presentation in everyday urological practice. The prevalence of renal calculi ranges from 4% to 20% in different geographical distribution. Anatomical variation in renal collecting system plays a significant role in formation of calculi in its parts. The large extra renal pelvis leads to stagnation of urine for longer durations and formation of stones. The stone free rate after percutaneous nephrolithotomy and extra corporeal shock wave lithotomy is significantly related to anatomical factors, particularly the type of renal pelvis and dimensions (length and width) of lower infundibulum. Previous authors described the morphology of pelvicalyceal system in a highly variable manner and the available anatomical description of pelvicalyceal system is contradictory and incomplete. Hence an attempt has been made to provide the precise anatomy of pelvicalyceal system in adult human kidneys.

Methods

We studied 196 formalin embalmed kidneys to note the number of infundibulum, major and minor calyces. The location and shape of pelvis were also studied.

Results

The intra-renal pelvis was narrow and had funnel shaped appearance in 95 of total 196 (48.5%) specimens, and the extra-renal pelvis was dilated as balloon shaped in 43 of 196 (21.9%) specimens. In 41 (20.9%) specimens, the renal pelvis was having partially intra- and extra-renal in location. Bilateral symmetry was found in only 27.1% of 196 renal collecting systems. The length of lower infundibulum was more than 22 mm in 19 (9.7%) of 196 cases which directly affects the stone clearance rate during open and endoscopic surgeries on pelvicalyceal system.

Conclusion

This study provides the accurate morphological details of the shape and dimensions of renal pelvicalyceal system to help the urologists and nephrologists.

Do the variations in renal pelvic angles play a role in the formation of renal stone? A computed tomography study

OBJECTIVE

In this study, we aimed to investigate the effect of variations in renal pelvic angle on urinary calculi development.

MATERIALS AND METHODS

A total of 2456 unenhanced abdominal CT scans were retrospectively evaluated and 262 kidneys of 131 patients were compared. Patients included in this study were identified and qualified as follows: Having unilateral calculi, having no calculi or a history of calculi in contra-lateral side and having totally normal renal morphology.

RESULTS

The mean angle of kidneys with calculi was 55 ± 9°, while the average angle measurement was 61 ± 11° in kidneys without calculi. The mean angle measured from the kidneys with calculi was statistically smaller (p < 0.001).

CONCLUSION

Our study suggests that the possibility of calculi development in kidneys, which have more anteriorly localized pelvic angulation tends to be significantly higher in individuals, who did not have any congenital or acquired renal pathology before.

Anatomic predictors of formation of lower caliceal calculi: is it the time for three-dimensional computed tomography urography?

OBJECTIVE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Imaging modalities for urolithiasis: impact on management

PURPOSE OF REVIEW

Urolithiasis is a common urological problem, often requiring efficient workup, accurate diagnosis, and treatment. The purpose of this review is to summarize the imaging modalities employed for the diagnosis of calculi and the caveats of different clinical situations.

RECENT FINDINGS

Noncontrast computed tomography has become the most universally used imaging tool for diagnosing urolithiasis, although ultrasound and magnetic resonance imaging maintain specific roles. Noncontrast computed tomography may provide prognostic information regarding the success of specific management strategies for urolithiasis. Additionally, noncontrast computed tomography is being tested in lower-radiation dose protocols with promising results.

SUMMARY

Considering the well supported accuracy and relative ease of use of noncontrast computed tomography, it has become a logical choice for the urologist to use the technique as a diagnostic tool for stone disease. The future of imaging for intervention and surveillance of stone disease lies in the continued progress of noncontrast computed tomography in terms of patient safety. This will need to be done by developing low-dose radiation computed tomography that can replicate the efficacy of current noncontrast computed tomography.

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 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).

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.