Incidence and characteristics of kidney stones in patients with horseshoe kidney: A systematic review and meta-analysis

A narrative review on extracorporeal shock wave lithotripsy, ureterolithotripsy, and percutaneous nephrolithotripsy in patients with anomalous kidneys

INTRODUCTION

The aim of this paper was to review the outcomes of shock wave lithotripsy (SWL), ureteroscopy, and percutaneous nephrolithotripsy (PCNL) in kidney stone patients with Congenital Anomalies of the Kidney and Urinary Tract (CAKUT).

EVIDENCE ACQUISITION

A literature search was performed on 15th November 2023 and updated on 18th October 2024 using Cochrane Central Register of Controlled Trials, PubMed, Scopus and Google Scholar with no date limit. Preclinical and animal studies, reviews, letters to editor, case reports, pediatric studies were excluded. Only English papers were included.

EVIDENCE SYNTHESIS

Forty-one articles were accepted. Seventeen studies focused on horse-shoe kidney (HSK). Among these, 3 papers focused on RIRS, 9 on PCNL, 5 compared RIRS vs PCNL. The remaining ones explored SWL, RIRS, PCNL in ectopic, malrotated and medullary sponge kidney and caliceal diverticulum stones. HSK, caliceal diverticulum and malrotated kidneys stones treated with SWL have poor stone-free rate, while the best choices are PCNL and ureteroscopy. In ectopic kidneys the best choice is ureteroscopy, SWL has poor stone-free rate, while PCNL is less safe for higher bowel injury risk. In medullary sponge kidneys regardless of the treatment used, stone-free rate is low, with a higher rate of retreatment.

CONCLUSIONS

SWL has lower stone-free rate and higher retreatment in all types of CAKUT but has the lowest rate of complications. PCNL has the best stone-free rate in large stone burdens and RIRS is effective procedure although higher reintervention rate and need of pre-stenting in some cases.

Reviewing the complexities of horseshoe kidney: insights into embryogenesis and surgical considerations

Horseshoe kidney (HSK) is a common renal malformation with unique and complex characteristics. A systematic literature search was conducted using PubMed and ScienceDirect databases. Several theories have been proposed regarding HSK formation, such as the close apposition of the kidneys during ascent through an arterial fork, lateral flexion of the trunk, and caudal embryonic rotation. Emerging evidence from animal models implicates notochord signaling and the sonic hedgehog pathway in HSK formation. The isthmus, a defining feature of HSK, is hypothesized to arise from ectopic mesenchymal tissue. The surgical anatomy of HSK is complex, given the variability in location, orientation, and blood supply. Both arterial and venous anatomy exhibit significant variability, raising questions about whether anomalous blood supply is a cause or a consequence of abnormal renal position. The isthmus usually contains functional renal parenchyma and fusion between the kidneys, primarily at the lower pole. While it is often stated that the inferior mesenteric artery is "held back" at the L3 level, this anatomical configuration is present in only 40% of cases. The review highlights the need for further research and provides a comprehensive overview of HSK knowledge.

Metabolic Evaluation and Recurrence Prevention for Urinary Stone Patients: An EAU Guidelines Update

BACKGROUND AND OBJECTIVE

The aim of this review was to define patients who are at high risk of recurrence of urolithiasis, to delineate diagnostic and therapeutic algorithms for each type of stone, and to clarify general guidelines and recommendations for prevention of recurrence.

METHODS

A professional research librarian carried out literature searches for all sections of the urolithiasis guidelines, covering the timeframe between 1976 and June 2023.

KEY FINDINGS AND LIMITATIONS

For every patient with urolithiasis, an attempt should be made to analyse the stone. Patients should be given general instructions on how to prevent recurrence, including adequate fluid and calcium intake, and low consumption of sodium and protein. Identifying and correcting the causative factors is a cornerstone in preventing the recurrence of urolithiasis. Diagnostic and therapeutic algorithms by stone composition are available. Every patient should undergo baseline metabolic screening, while patients with calcium stones, who are at high risk of relapse and complications, should undergo extensive metabolic screening with two 24-h urine collections and should receive targeted therapy. Patients with uric acid, infection, or cystine stones are at high risk of relapse. All patients at high risk of recurrence should be closely monitored, especially those not complying with therapy in the long term.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Metabolic stone evaluation and patient follow-up are highly recommended to prevent urolithiasis recurrence.

Association of different obesity indices with nephrolithiasis in community-dwelling older adults

BACKGROUND AND OBJECTIVE

Obesity has been linked to various conditions, including nephrolithiasis. Given the rising prevalence of both nephrolithiasis and obesity in older adults, this study aimed to examine the association of different obesity-related indices with nephrolithiasis.

METHODS

This cross-sectional study included 2419 individuals (mean age 69.34 ± 6.40; 51.92 % female) from the Bushehr Elderly Health (BEH) program, a population-based measured using Dual-energy X-ray absorptiometry (DXA), while nephrolithiasis history was assessed through medical records. The associations between obesity-related indices and nephrolithiasis were analyzed using multivariable logistic regression models, adjusted for relevant confounders.

RESULTS

Among the 2419 participants, 212 (8.76 %) had a history of nephrolithiasis. In the overall population, only the android-to-gynoid fat mass (FM) ratio was significantly associated with nephrolithiasis (odds ratio [OR] 3.28, 95 % Confidence Interval [CI] 1.06-10.18). In females, the trunk-to-limb FM ratio (OR 2.62, 95 % CI 1.10-6.23) and the visceral adipose index (VAI) (OR 1.092, 95 % CI 1.005-1.187) were associated with nephrolithiasis. In males, only the body adipose index (BAI) was significantly associated with nephrolithiasis (OR 1.082, 95 % CI 1.017-1.151).

CONCLUSION

In this study, the android-to-gynoid FM ratio in the total population, the trunk-to-limb FM ratio and VAI in females, and BAI in males were significantly associated with nephrolithiasis. Monitoring and managing these indices may enhance quality of life for elderly individuals by facilitating early diagnosis of nephrolithiasis and preventing stone formation.

Supine percutaneous nephrolithotomy in horseshoe kidney

Introduction

Historically, percutaneous nephrolithotomy (PCNL) in horseshoe kidney (HSK) patients has been performed in the prone position. Nevertheless, thanks to the spread of the supine PCNL technique for patients with urinary stones and normal renal anatomy, some retrospective studies have already reported on supine PCNL and HSK, showing the effectiveness and safety of the procedure. Herein we report our experience with supine PCNL in a subset of patients with urolithiasis.

Material and methods

Prospective data were collected for all HSK patients who underwent supine PCNL at our institution from June 2016 to June 2023. Stone volume was reported as the volume of a single stone or the sum of the volumes of multiple stones on computed tomography (CT) images. Patients were reported to be stone-free if there were no stones on postoperative non-contrast CT (NCCT) exam. Peri-/postoperative complications were reported according to the Clavien-Dindo classification system. The primary endpoint of the study was stone-free rate (SFR) and the secondary endpoints were Clavien-Dindo complications Grade I or higher.

Results

A total of 35 patients met the inclusion criteria and were enrolled in the study. Forty-eight procedures were analyzed. SFR was 72.9% at 1-month follow-up. In 11 out of 48 procedures (22.9%) Clavien-Dindo Grade I-II complications were recorded. In one case Clavien-Dindo Grade IIIa complication was observed.

Conclusions

In this prospective study of 35 HSK patients who underwent 48 procedures, supine PCNL was safe and effective, with minimal morbidity.

An Unusual Case of Flank Pain Late in Life: A Case Report

Abnormalities in renal fusion represent a subset of congenital anomalies of the kidneys and urinary tract (CAKUT). Horseshoe kidneys (HSKs) are the fusion of kidneys at their lower poles. It is the most common form of CAKUT. Symptoms are usually subtle. The diagnosis is usually made incidentally during childhood. Rarely does an HSK become symptomatic later in life. We present the case of an 88-year-old female with a history of HSK who presented to the emergency department (ED) with a three-week history of left-sided flank pain, intermittent nausea, and reduced urine output. Her inpatient workup included imaging that revealed an HSK and bilateral hydronephrosis, which was more prominent on the left. The onset of symptoms for an HSK late in life is extremely rare.

Combined laparoscopic pyelolithotomy with retrograde intrarenal surgery in a patient with horseshoe kidney anomaly and kidney stone: a case report

Horseshoe kidney is the most prevalent congenital kidney fusion anomaly, affecting 0.25% of the general population and occurring in 1 in 400-1600 births. Approximately 40 percent of patients develop kidney stones due to anomalies. In our case, we aimed to perform combined laparoscopic pyelolithotomy with retrograde intrarenal surgery (RIRS) instead of percutaneous nephrolithotomy (PNL) in a patient with a horseshoe anomaly. This procedure enabled us to detect the location of the mobile stone with RIRS and then successfully extract it with laparoscopic pyelolithotomy. Laparoscopic pyelolithotomy combined with RIRS is a reasonable additional treatment option for complicated stone surgery due to horseshoe kidney anomalies.

Supine mini percutaneous nephrolithotomy in horseshoe kidney

OBJECTIVE

The percutaneous nephrolithotomy (PCNL) in Horseshoe kidneys (HSK) is usually performed in the prone position, allowing entry through the upper pole and providing good access to the collecting system. However, in patients with normal kidney anatomy, the supine position is reliable and safe in most cases, but it is unknown whether the supine position is adequate in patients with HSK. The purpose of this study was to describe the results of PCNL in HSK in three different surgical institutions and to evaluate the impact of supine position during surgery, comparing pre-operative and post-operative data, complications, and stone status after surgery.

MATERIAL AND METHODS

Between 2017 and 2022, a total of 10 patients underwent percutaneous renal surgery for stone disease in HSK. All patients were evaluated pre- and post- operatively with non-contrast CT. we evaluated patients (age and gender), stones characteristics (size, number, side, site and density ), and outcomes. The change in haemoglobin, hematocrit, creatinine and eGFr were assessed between the most recent preoperative period and the first postoperative day. Procedure success was defined as stone-free or presence of ≤4 mm fragments (Clinically Insignificant residual Fragments - CIrF). Complications were registered and classified according to Clavien-dindo Grading System, during the 30 - day postoperative period and Clavien scores ≥ 3 were considered as major complications. Statistical analysis was performed using "r 4.2.1" software, with a 5% significance level. we also compared pre-operative and post-operative data using "wilcoxon signedrank test".

RESULTS

No statistical difference was observed between preoperative and post-operative renal function data. At one post operative day CT scan, an overall success rate of 100% was registered. 9/10 patients were completely free from urolithiasis (stone-free rate: 90%), while 1/10 patients had ≤4 mm residual stone fragments (CIrF rate: 10%). No cases of intraoperative complications were registered. Post-operative complications were reported in 1/10 patients. A patient developed urosepsis (defined as SIrS with clinical signs of bacterial infections involving urogenital organs - Clavien-dindo Grade II) after procedure, and was treated with intravenous antibiotic therapy successfully.  Conclusions: This study shows that in patients with HSK mini- PCNL in supine position allows to achieve good stone free rate with a very low morbidity. According to our series, the described technique for PCNL in HSK should be an option. Nevertheless these results must be confirmed by further studies.

Comparative evaluation of urolithiasis management options in patients with horseshoe kidney: A systematic review and meta-analysis

Background

Horseshoe kidney is a rare congenital anomaly commonly complicated by urolithiasis. Extracorporeal shockwave lithotripsy (ESWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL) are treatment options for horseshoe kidney stones. The aim of this systematic review is to compare the benefits and risks of these management options.

Methods

MEDLINE, EMBASE, and Cochrane Library databases were searched from inception to February 2022. A total of 516 nonduplicate studies were screened against the inclusion and exclusion criteria. Studies comparing at least 2 interventions with ≥10 patients per intervention were included.

Results

Nine retrospective observational studies published from 2007 to 2021 with a total of 565 patients were included. Reported mean ± SD or mean (range) stone sizes ranged between 17.90 ± 2.43 mm and 27.9 ± 8.6 mm for PCNL, 8.4 (2-25) mm and 22.3 ± 9.1 mm for URS, and 11.9 ± 2.0 mm and 16.8 ± 4.4 mm for ESWL. There was no difference in single-session and overall stone-free rate (SFR) between PCNL and URS, with a risk ratio of 1.04 (95% confidence interval, 0.95-1.13; I2 = 20.63%). Ureteroscopy had better stone clearance than ESWL, with an overall SFR risk ratio of 1.38 (95% confidence interval, 1.04-1.82; I2 = 0%). There was no statistically significant difference in overall SFR between PCNL and ESWL. Most patients who underwent URS and ESWL experienced Clavien-Dindo (CD) grade I-II complications. Percutaneous nephrolithotomy was associated with the highest complication rates, including 5 CD grade III and 3 CD grade IV complications and a mean postoperative hemoglobin drop of 0.47 to 1.83 g/dL. There were no CD grade V complications across all studies.

Conclusions

There was no difference in SFR between PCNL and URS. Ureteroscopy was associated with a smaller stone burden and fewer and less severe complications. Ureteroscopy was found to be more effective than ESWL with a higher SFR and comparable safety profile. Further large-scale randomized controlled trials are needed to confirm these findings.

Non-papillary prone percutaneous nephrolithotomy for renal abnormalities: single-institution experience

PURPOSE

To evaluate the effectiveness and safety of non-papillary prone PCNL for the treatment of patients with renal abnormalities.

METHODS

An observational retrospective cohort study including PCNL cases of patients with renal abnormalities was performed. The following inclusion criteria were applied: renal stones > 1.5 cm with maximal diameter, anatomical malformations of affected kidney (malrotated kidneys, horseshoe kidneys and kidneys with complete duplicated systems, medullary sponge kidney), patients treated with standard (30Fr) PCNL or mini-PCNL (22Fr). The lithotripsy was performed using the Lithoclast Master or the Lithoclast^® Trilogy (EMS Medical, Nyon, Switzerland).

RESULTS

Overall, 57 patients, 35 males, and 22 females with any renal malformation underwent non-papillary prone PCNL. Our study included 25 patients with horseshoe kidneys, 21 with malrotated kidneys, 9 with kidneys with duplicated pelvicalyceal systems and 2 with medullary sponge kidneys. The mean cumulative stone size was 36 ± 1.4 mm and most of the stones were in the lower calyceal group (36.9%) and in the pelvis (27.2%). The stone-free rate (SFR) was 84.2% and the mean hospitalization time was 2.7 ± 0.7 days. In total, postoperative complications were developed in six patients (10.5%), half of them presenting fever and the other half requiring blood transfusion (Grade II).

CONCLUSION

The PCNL is the method of choice for treating large stones in anomalous kidneys. The generally accepted panacea that only a papillary puncture is safe is questioned by our results. Based on our experience, a non-papillary puncture proved to be a safe and effective procedure.

Single-use versus conventional reusable flexible ureteroscopes - an evaluation of the functional parameters

The purpose of single-use flexible ureteroscopes (su-fURS) was to overcome the limitations of conventional reusable ureteroscopes in terms of maneuverability and maintenance. We aimed to perform a systematic literature review on available su-fURS performance versus conventional reusable fURS focusing on clinical data. A systematic research using Pubmed was performed evaluating single-use fURS and reusable fURS in urinary tract stone disease, including prospective assessments and case series. This review aimed to provide an overview of single-use and disposable flexible ureteroscopes and to examine and compare their capabilities (deflection, irrigation, optical properties). We included 11 studies, where the single-use fURS were compared to the reusable fURS. The studies with single-use ureteroscopes included data on LithoVue (Boston Scientific), The Uscope UE3022 (Pusen, Zhuhai, China), NeoFlex-Flexible, (Neoscope Inc San Jose, CA), 23 YC-FR-A (Shaogang). For reusable ureteroscopes, data were included on three models, two digital (Karl Storz Flex-XC and Olympus URF-Vo) and one fiber optic (Wolf-Cobra). There were no significant differences in stone-free rate, procedure duration, or functional capabilities between single-use fURS and reusable fURS. The systematic literature review analyzed operative time, functional capabilities, stone-free rates, and postoperative complications of the ureteroscopes, and a special chapter about renal abnormalities to emphasize that they are a good choice having a high proportion of stone-free rates and few risks, particularly in treating difficult-to-access calculi. Single-use fURS demonstrate a comparable efficacy with reusable fURS in resolving renal lithiasis. Further studies on clinical efficacy are needed to determine whether single-use fURS will reliably replace its reusable counterpart.

Challenges and options for management of stones in anomalous kidneys: a review of current literature

Introduction

Congenital anomalies of the kidney and urinary tract (CAKUT) represent a wide range of disorders that result from developmental abnormalities of the kidneys, urinary collecting tract, and lower urinary tract. There has been extensive development in approaches to the management of stones in normal kidneys with the advent of retrograde intra-renal surgeries (RIRS)/ureteroscopies, extracorporeal shock wave lithotripsy (ESWL) percutaneous nephrolithotomy (PCNL), and minimally invasive surgery (laparoscopy/robotics). However, the management of stones in CAKUT is not straightforward and is often challenging for urologists. There are no clear guidelines available to help navigate stone management in such patients.

Materials and methods

The aim of this literature review was to focus on stone management in anomalous kidneys. Most common abnormalities were considered. The studies were very heterogeneous with different approaches. The methodology involved evaluating studies looking into individual surgical approaches to the management of stones in these anomalous kidneys as well as looking at different approaches to stone management, in particular renal abnormality.

Results

We found RIRS is a feasible approach in most stones with sizes <20 mm and PCNL holds the upper hand in stones more than 20 mm. However, ESWL, laparoscopy, and robotics have their places in managing some of these cases.

Conclusion

We concluded that stones in anomalous kidneys can be challenging but can be managed safely. There is no straightforward answer to the right technique but rather the right planning based on the anatomy of the kidney in terms of vascularity and drainage, stone size and density, and expertise available.

Propensity score-matched analysis comparing retrograde intrarenal surgery with percutaneous nephrolithotomy in anomalous kidneys

BACKGROUND

Endourologic interventions for urolithiasis in patients with anomalous kidneys can be challenging, and comparisons between these interventions are not well studied. We aim to compare the safety, outcomes and complications of retrograde intrarenal surgery (RIRS) versus percutaneous nephrolithotomy (PCNL) in patients with urolithiasis in anomalous kidneys.

METHODS

A propensity score-matched pair analysis (PSM) was performed on pooled patient data from 20 centers. 569 patients with anomalous kidneys (horseshoe kidney [HSK], ectopic kidney, malrotated kidney) and urolithiasis who received either PCNL or RIRS as the primary modality of intervention from 2010 to 2020 were analyzed. Patients were matched based on calculated propensity scores by a regression model using age, sex, comorbidities, stone size, and renal anomaly type as co-variates. Multivariate logistic regression of factors (mode of treatment [PCNL or RIRS], comorbidities, stone size) and their effects on outcomes of stone-free rate (SFR), need to abandon surgery due to intraoperative difficulty, postoperative hematuria and sepsis and were analyzed when applicable.

RESULTS

After PSM, there were a total of 127 pairs in each group. Overall, PCNL conferred a higher SFR compared to RIRS (OR=3.69, 95% CI 1.91-7.46, P<0.001), particularly in HSK (OR=3.33, 95% CI 1.22-9.99, P=0.023), and ectopic kidneys (OR=18.10, 95% CI 3.62-147.63, P=0.002), with no significant difference in malrotated kidneys. There was no significant difference in postoperative sepsis observed. Surgery was abandoned more often in RIRS than PCNL (6.3% vs. 0%, P=0.014). Although PSM provides a robust analysis due to baseline differences in the unmatched cohorts, this study was limited by an inevitable degree of selection bias.

CONCLUSIONS

While both modalities are safe and efficacious, PCNL yields better SFR than RIRS in patients with anomalous kidneys, with no difference in postoperative sepsis rates. Patients may benefit from personalized management best carried out in high volume endourology centers.

Optimal patient position for percutaneous nephrolithotomy in horseshoe kidneys: Traditional prone or supine?

OBJECTIVE

Although it was stated that supine percutaneous nephrolithotomy (PCNL) was associated with relatively shorter surgical times and comparable success and complication rates, there is no consensus in the current literature concerning the safety and efficacy of supine PCNL in patients with horseshoe kidneys. We aimed to compare supine and prone PCNL regarding safety and efficacy in patients with horseshoe kidneys.

METHODS

Data of the patients with horseshoe kidneys who underwent PCNL for renal stones larger than 2 cm between January 2010 and May 2021 were retrospectively reviewed. The study patients were categorized as Group 1 (i.e., supine PCNL-SPCNL) and Group 2 (i.e., prone PCNL-PPCNL). Both groups were compared regarding demographic, clinical, and surgical data.

RESULTS

Sixty-five patients were included. Among these patients, 31 (47.7%) were in Group 1, while 34 (52.3%) were in Group 2. Both groups were statistically similar in terms of demographic data, stone characteristics, perioperative parameters, and complication rates (p > 0.05). There was no statistical difference in terms of additional treatment rates, stone-free rates in the postoperative second-day and third-month evaluations (p > 0.05). Mean surgical time was significantly longer in Group 2 (113 ± 17.1 min) than in Group 1 (90.6 ± 11.3 min) (p = 0.000).

CONCLUSION

Although it is traditionally performed in the prone position, the supine approach is as safe and effective as the prone approach. In addition, the supine approach is associated with significantly shorter surgical times.

Is there a correlation between urolithiasis in horseshoe kidneys and isthmus thickness or renal angulation?

Background:

Stone disease is a common complication of horseshoe kidneys (HSK). There are currently limited studies that examine the relationship between HSK anatomy and stone formation. We aim to determine if there is such an association by measuring the isthmus size and renal angulation in both stone and non-stone forming HSK using computed tomography (CT).

Method:

This is a retrospective study performed at a single tertiary centre. Using the radiological information system, all CT reports between 01 January 2010 and 31 December 2015 were searched for the keyword ‘horseshoe’ on the radiological information system. This produced a list of 285 reports. Each report and image packet of these 285 studies were reviewed to confirm the presence of an HSK and duplicate patients from multiple examinations were highlighted. One hundred and thirty-eight unique HSK patients were obtained and the studies were assessed for the presence or absence of stones. A total of 112 HSK were found; 88 of which contained no stone and 24 with stone. Angle measurements and isthmus size were measured on these kidneys. As axial images are obtained as standard in all cases, these measurements were all obtained in the axial plane. All parameters were measured and recorded manually by one person so as to reduce inter-observer variability.

Results:

Isthmus size varied widely, measuring from 2 to 39 mm. Right renal angle ranged from 51 to 158°, left 38 to 152°.

Conclusion:

The isthmus size and renal angle measurements were not found to be significant determinants for stone disease in our patient population.

Single-Use vs Reusable Ureteroscopes in Horseshoe Kidney Stones

Introduction: Horseshoe kidney (HSK) is one of the most frequent renal malformations which appears to present an increased risk of stone formation caused by abnormal urine drainage. This study aims to compare the results of single-use flexible ureteroscopy (SUfURS) vs reusable devices (RfURS) with holmium laser in treating stones in HSK cases. Material and method: Between February 2017 and June 2021, 29 patients diagnosed with renal stone disease and horseshoe kidney were retrospectively analyzed. Subjects were divided into two groups: Group 1 (14 patients) undergoing SUfURS and Group 2 (15 patients) operated with RfURS devices. We analyzed the mean stone burden, operation time, stone free rate and complications. The surgical equipment was represented by the SUfURS PU3022 (Zhuhai Pusen Medical Technology) and RfURS URF-V2 (Olympus). Results: The two groups had a similar mean stone burden: 22 ± 6 mm (range 15-31 mm) for Group 1 and 24 ± 7 mm (range 16-30 mm) for Group 2. The average operative time was better for Group 1 (86 ± 17 min) vs Group 2 (89 ± 20 min). The stone-free status was similar for both groups after the first session (57.14% for Group 1 vs 53.33% for Group 2) and slightly in favor of Group 1 as compared to Group 2 (85.71% vs 73.33%, respectively) after the second session. The overall complication rate (Grades I, II and III) was almost similar in both groups, with a slightly prevalence for Group 1 (no major complications Grade IV and V). Conclusion:Flexible ureteroscopy represents an effective alternative treatment technique for large stones in kidney abnormalities. single-use flexible ureteroscopy can be successfully used to treat patients with genetically renal malformations and its results may be slightly better than those provided by using RfURS devices.

Real-world Global Outcomes of Retrograde Intrarenal Surgery in Anomalous Kidneys: A High Volume International Multicenter Study

OBJECTIVE

To analyze the trends and outcomes of retrograde intrarenal surgery for treatment of urolithiasis in anomalous kidneys in a large international multicenter series.

MATERIALS AND METHODS

We designed a multicentric retrospective study. Nineteen high-volume centers worldwide were included. Pre-, peri- and postoperative data were collected, and a subgroup analysis was performed according to renal anomaly.

RESULTS

We analyzed 414 procedures: 119 (28.7%) were horseshoe kidneys, 102 (24.6%) pelvic ectopic kidneys, 69 (16.7%) malrotated kidneys and 50 (12.1%) diverticular calculus. The average size (SD) of the stone was 13.9 (±6) millimeters and 193 (46.6%) patients had a pre-operative stent. In 249 cases (60.1%) a disposable scope was used. A UAS (ureteral access sheath) was used in 373 (90%) patients. A Holmium laser was used in 391 (94.4%) patients. The average (SD) operating time was 65.3 (±24.2) minutes. Hematuria, caliceal perforation and difficulty in stone localisation were mostly seen in diverticular stones and difficulty in UAS placement and lithotripsy in the cases of renal malrotation. The overall complication rate was 12%. Global stone-free rate was 79.2%. Residual fragments (RF) were significantly lesser in the pre-stented group (P <.05). Diverticular calculi was the group with more RF and needed ancillary procedures (P <.05).

CONCLUSION

Retrograde intrarenal surgery in patients with anomalous kidneys is safe and effective with a high single-stage stone-free rate and low complication rate. There is a trend toward using smaller and disposable scopes and smaller UAS. Diverticular stones can still be challenging with higher rates of intraoperative hematuria, caliceal perforation and RF.

Variations of stress field and stone fracture produced at different lateral locations in a shockwave lithotripter field

During clinical procedures, the lithotripter shock wave (LSW) that is incident on the stone and resultant stress field is often asymmetric due to the respiratory motion of the patient. The variations of the LSW-stone interaction and associated fracture pattern were investigated by photoelastic imaging, phantom experiments, and three-dimensional fluid-solid interaction modeling at different lateral locations in a lithotripter field. In contrast to a T-shaped fracture pattern often observed in the posterior region of the disk-shaped stone under symmetric loading, the fracture pattern gradually transitioned to a tilted L-shape under asymmetric loading conditions. Moreover, the model simulations revealed the generation of surface acoustic waves (SAWs), i.e., a leaky Rayleigh wave on the anterior boundary and Scholte wave on the posterior boundary of the stone. The propagation of SAWs on the stone boundary is accompanied by a progressive transition of the LSW reflection pattern from regular to von Neumann and to weak von Neumann reflection near the glancing incidence and, concomitantly, the development and growth of a Mach stem, swirling around the stone boundary. The maximum tensile stress and stress integral were produced by SAWs on the stone boundary under asymmetric loading conditions, which drove the initiation and extension of surface cracks into the bulk of the stone that is confirmed by micro-computed tomography analysis.

Renal Displacement with Supine to Prone Positional Change: Effect of Sex and BMI

OBJECTIVE

To determine patterns of kidney and retroperitoneal organ movement during positional change between the supine and prone positions as seen on computed tomography (CT) scans.

METHODS

Axial CT scans of 75 subjects who underwent supine and prone were retrospectively analyzed. A total of 1650 measurements were taken for anterior-posterior, medial-lateral, cranial-caudal, skin-to-calyx distance, kidney-to-liver distance, and kidney-to-colon distance in both positions.

RESULTS

Pronation shortens the distance from the skin to renal calyx for both the right (99.62 mm vs. 85.14 mm; p < 0.00001) and left (96.67 mm vs. 90.80 mm; p < 0.00001) sides. The reduction in left-side tract length for obese patients is significantly greater than that of normal weight patients (11.88 mm vs. -5.02 mm; p = 0.001). The left kidney displaces ventrally (11.12 mm vs. 18.59 mm; p < 0.00001) while the right kidney does not (14.26 mm vs. 15.30 mm; p = 0.30). The right kidney displaces cranially (62.76 mm vs. 79.51 mm; p < 0.00001) while the left kidney does not (64.35 mm vs. 66.52 mm; p = 0.14). The left kidney in females moves medially while no change is seen in males (4.22 mm vs. -0.48 mm; p = 0.0004). The left kidney in females displaces towards the descending colon while it moves farther away in males (2.73 mm vs. -2.01 mm; p = 0.011).

CONCLUSIONS

Both sex and BMI had effects on the movement of the kidneys upon pronation. The differences can be clinically useful to help pre and intraoperative planning.

Supine tubeless PCNL in horseshoe kidney (a series of cases)

OBJECTIVE

Objective of this case series is accurate access to the respective calyx with stone in horseshoe kidney while performing percutaneous nephrolithotmy in supine position. Reducing operative time and anaesthetic morbidity while performing percutaneous nephrolithotomy in horseshoe kidney with nephrolithiasis in supine position.

MATERIALS AND METHODS

Four patient with one having bilateral renal calculi with horshoe kidney were selected randomly. There were no preference for age, gender; size, location and laterality of stone or BMI. All the patients fit into the AUA guideline criteria for management by percutaneous nephrolithotomy. Preoperative, perioperative and follow up data were collected.

RESULTS

Four patients with one having bilateral renal calculi underwent supine tubeless PCNL in 1 year in GMSV position. There was no intraoperative, post operative or on follow up complications in any patient. In all the patients stones were cleared completely in single setting.

CONCLUSION

Supine percutaneous nephrolithotomy in horseshoe kidney is an alternative to the standard prone percutaneous nephrolithotomy in the horseshoe kidney. It provides an additional benefit of performing the procedure in a single position, which is known to reduce total operating time, less anaesthesia related complications and less neuromusculoskeletal injury.

Side-by-side evaluation of virtual non-contrast and post-contrast images improves detection of clinically significant urolithiasis on single-phase split bolus dual-energy CT urography

OBJECTIVES

Studies show insufficient sensitivity of virtual non-contrast (VNC) reconstructions for stone detection in dual-energy CT urography (DE-CTU). The aim of this study was to investigate if side-by-side-evaluation of both VNC and post-contrast images could increase the sensitivity of single-phase split bolus DE-CTU.

METHODS

Consecutive patients with haematuria who underwent split bolus DE-CTU on the same dual-source DE-CT scanner were retrospectively enrolled in the study. Intravenous furosemide and oral hydration were employed. Two readers, independently and then jointly in two separate sessions, recorded the location and the longest axial stone diameter on three randomised sets of images: separate VNC and post-contrast images, and side-by-side-reconstructions. True non-contrast (TNC) images served as the standard of reference.

RESULTS

A total of 83 urinary stones were detected on TNC images. Independent reader side-by-side-evaluation of VNC and post-contrast images yielded higher stone detection sensitivity (76 and 84%, respectively) compared to evaluation of only VNC (71 and 81%, respectively) or post-contrast images (64 and 80%, respectively). The sensitivity of joint reader evaluation of side-by-side-images reached almost 86% and was not significantly different from TNC images (p = 0.77). All stones larger than 3 mm were correctly detected by side-by-side-evaluation. Dose reduction of 55% could be achieved by omitting TNC scans.

CONCLUSION

Side-by-side-VNC and post-contrast image evaluation enable detection of clinically significant urolithiasis on single-phase split bolus DE-CTU with significant dose reduction.

ADVANCES IN KNOWLEDGE

This study shows that single-phase DE-CTU is feasible if VNC imaging is simultaneously utilised with post-contrast images.

Malformative Reno-Urinary Pathology in Patients with HIV Infection-Clinical and Therapeutic Implications

Chronic kidney disease is an important comorbidity of HIV infection causing real problems in the evolution and medical healthcare of HIV-positive patients. In recent years, a significant number of HIV-positive patients develop renal dysfunction, several mechanisms being incriminated: direct effect of the virus, toxic effect secondary to of antiretroviral medication, secondary to associated comorbidities, given that life expectancy has increased significantly in the last decade, thanks to the use of antiretroviral therapies. There are few studies in the literature to evaluate malformative renourinary pathology in patients with HIV infection. We present the case of a patient with HIV infection, horseshoe kidney, chronic kidney disease and incomplete Fanconi syndrome, secondary to the administration of tenofovir fumarate, a nucleoside reverse transcriptase inhibitor. Malformations, abnormalities or dysmorphysms of the renal tract should be considered in the HIV-positive patient with secondary renal dysfunction because they take a wide range of forms, are underdiagnosed and predispose to multiple complications, with varying degrees of severity, such as urinary tract infections, renal stones or progression of chronic kidney disease. Tenofovir fumarate and atazanavir must be avoided in patients with HIV infection and chronic renal dysfunction.

Renal outcomes in adult patients with horseshoe kidney

BACKGROUND

Horseshoe kidney (HSK) is a congenital disorder that is usually asymptomatic, but that increases the risks of kidney stones and infectious disease. However, renal outcomes such as end-stage renal disease (ESRD) in patients with HSK remain unclear.

METHODS

In total, 146 patients with HSK (age of ≥20 years) from two tertiary hospitals were included in this study. Control individuals who underwent medical check-ups were selected by matching for age, sex, serum creatinine level, hypertension and diabetes. The hazard ratios (HRs) for the risks of ESRD and all-cause mortality were calculated after adjustment for multiple variables.

RESULTS

The proportions of HSK-related complications for obstruction, kidney stones, urinary tract infection and urogenital cancer were 26, 25, 19 and 4%, respectively. During the median follow-up period of 9 years (maximum 32 years), the incidence of ESRD was 2.6/10 000 person-years. The risk of ESRD in patients with HSK was higher than in control individuals [adjusted HR = 7.6; 95% confidence interval (CI) 1.14-50.47]. All-cause mortality did not differ between the two groups (adjusted HR = 0.6; 95% CI 0.08-4.29).

CONCLUSIONS

Patients with HSK are at risk of ESRD, which may be attributable to the high prevalence of complications. Accordingly, these patients should be regarded as having chronic kidney disease and require regular monitoring of both kidney function and potential complications.

Percutaneous Nephrolithotomy in Horseshoe Kidneys: Results of a Multicentric Study

Objective: To report the outcomes of percutaneous nephrolithotomy (PCNL) in horseshoe kidneys (HSK) in 12 institutions worldwide and evaluate the impact of patient position during operation. Methods: We carried out a retrospective analysis of PCNL procedures performed between 2008 and 2018 in patients with HSK. Pre-, peri-, and postoperative data were collected, and a subgroup analysis was performed according to patient position. Success was defined as an absence of >4-mm fragments. Values of p < 0.05 were considered significant. Results: We analyzed 106 procedures. The transfusion, complication, and immediate success rates (ISRs) were 3.8%, 17.5%, and 54.7%, respectively. The final success rate (FSR) increased to 72.4% after a mean of 0.24 secondary procedures. Logistic regression showed that higher body mass index (BMI) and stone size were significantly associated with residual fragments ≥4 mm. Sixty-seven patients (63.2%) were treated in prone and 39 (36.8%) in supine position. The prone group had a significantly higher BMI than the supine group (30.1 vs 27.7, p = 0.024). The transfusion, complication, and ISRs between the prone and supine groups were 4.5% vs 2.6% (p = 0.99), 16.9% vs 18.4% (p = 0.99), and 52.5% vs 69.2% (p = 0.151), respectively. Surgical time was significantly longer in the prone group (126.5 vs 100 minutes, p = 0.04). Upper pole was the preferred access in 80.3% of the prone group and 43.6% of the supine group (p < 0.001). The prone group had significantly more Clavien 2 complications than the supine (p = 0.013). The FSR in the prone and supine groups increased to 66.1% and 82.1% after 0.26 and 0.21 secondary procedures, respectively. No complications higher than Clavien 3 occurred. Conclusion: PCNL in patients with HSK is safe and effective with a low complication rate. Higher BMI and stone size negatively impacted outcomes. Supine PCNL may be an option for treating kidney stones in patients with HSK.

Split bolus dual-energy CT urography after urine dilution: a one-stop shop for detection and characterisation of urolithiasis

AIM

To determine the diagnostic performance of split-bolus dual-energy computed tomography (CT) urography (SBDECTU) in the detection and characterisation of urolithiasis.

MATERIALS AND METHODS

This single-centre Institute Ethics Committee (IEC)-approved prospective study was conducted from April 2014 to November 2015. One hundred and thirty consenting adults with microscopic haematuria underwent dual-energy true non-enhanced CT (DETNE) of the whole abdomen followed by a SBDECTU. The SBDECTU protocol consisted of synchronous nephrogram-urogram acquisition following urine dilution by oral hydration and normal saline injection. Calculi were detected and characterised using virtual non-enhanced (VNE) images derived from SBDECT were compared with DETNE (the reference standard). The subjective image quality and radiation dose were compared.

RESULTS

Twenty-six participants had one or more calculi (total 129 calculi) detected on DETNE CT. The sensitivity and specificity of VNE on a per-patient basis were 100%. Of the 129 calculi, 118 were detected on VNE, with a sensitivity of 91.47% and an accuracy of 91.47%. Of the calculi, 83.9% (99/118) could be characterised on SBDECTU images. On VNE images, complete iodine subtraction was seen in 73.1% (19/26). By omitting DETNE CT, the mean dose-length product of 537.6±152.9 mGy and volume CT dose index of 10.9±2.9 mGy•cm² could have been saved.

CONCLUSION

SBDECTU has high diagnostic accuracy in the detection and characterisation of clinically significant urinary calculi at potentially half the radiation dose.

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.

Standard-tract percutaneous nephrolithotomy for complicated calculi within horseshoe kidneys: A report of one case

A 48-year-old man was presented in the local hospitalized where he lived because of lower back pain one month ago. Then he came to our hospital for kidney stones on the right side within horseshoe kidneys and hydronephrosis diagnosed by imaging and abdominal ultrasound. After we proceeded single standard percutaneous nephrolithotomy with holmium laser combined EMS, his stones were totally removed with little intraoperative bleeding. No eventful post-operative complications occurred and the curative effect was very satisfied by KUB after stay in bed for 3 days reviewed. And a long-term follow up showed his recovery was quite well.

Mouse Models of Human Claudin-Associated Disorders: Benefits and Limitations

In higher organisms, epithelia separate compartments in order to guarantee their proper function. Such structures are able to seal but also to allow substances to pass. Within the paracellular pathway, a supramolecular structure, the tight junction transport is largely controlled by the temporospatial regulation of its major protein family called claudins. Besides the fact that the expression of claudins has been identified in different forms of human diseases like cancer, clearly defined mutations in the corresponding claudin genes have been shown to cause distinct human disorders. Such disorders comprise the skin and its adjacent structures, liver, kidney, the inner ear, and the eye. From the phenotype analysis, it has also become clear that different claudins can cause a complex phenotype when expressed in different organs. To gain deeper insights into the physiology and pathophysiology of claudin-associated disorders, several mouse models have been generated. In order to model human disorders in detail, they have been designed either as full knockouts, knock-downs or knock-ins by a variety of techniques. Here, we review human disorders caused by CLDN mutations and their corresponding mouse models that have been generated thus far and assess their usefulness as a model for the corresponding human disorder.

A deadly trap for para-aortic lymph node dissection in patients with horseshoe kidney as a complication: a case report

Horseshoe kidney is a rare congenital renal dysplasia. It is often associated with various anatomical abnormalities, including renal vessel and ureter variability, which increase unpredictable surgical risks. This current report describes the case of a 42-year-old woman diagnosed as having cervical squamous cell carcinoma complicated by horseshoe kidney. She underwent laparoscopic radical hysterectomy, bilateral oophorectomy and lymph node dissection, including dissection of the pelvic, presacral and para-aortic lymph nodes. The surgery was challenging, but no serious complications occurred. Postoperative multi-slice computed tomography angiography confirmed the anatomical variation of the renal location, ureter and renal vessels. To our knowledge, this is the first reported case of cervical carcinoma complicated with horseshoe kidney.

Outcomes of ureteroscopy for stone disease in anomalous kidneys: a systematic review

Introduction

Treatment of stone disease in anomalous kidneys can be challenging. As ureteroscopy (URS) has advanced, the number of studies reporting on outcomes of URS for stone disease in anomalous kidneys has increased. Our objective was to perform a systematic review of the literature to evaluate the outcomes of URS for stone disease in this group of patients.

Methods

A Cochrane style review was performed in accordance with the PRISMA guidelines using Medline, EMBASE, CINAHL, Cochrane Library, Scopus and individual urologic journals for all English language articles between inception and June 2018.

Results

Fourteen papers (413 patients) with a mean age of 43 years and a male to female ratio of 285:128 were included. The underlying renal anomaly was horseshoe kidney (n = 204), ectopic kidney (n = 117), malrotation (n = 86), cross fused ectopia (n = 2) and others (n = 2). With a mean stone size of 16 mm (range 2–35 mm), the majority of stones were in the lower pole (n = 143, 34.6%) or renal pelvis (n = 128, 31.0%), with 18.9% (n = 78) having stones in multiple locations. Treatment modality included the use of flexible ureteroscope in 90% of patients and ureteral access sheath used in 11 studies. With a mean operative time of 61.3 min (range 14–185 min), the initial and final SFR was 76.6% (n = 322) and 82.3% (n = 340), respectively. The overall complication rate was 17.2% (n = 71), of which 14.8% were Clavien I/II and the remaining 2.4% were Clavien ≥ III complications.

Conclusion

Although ureteroscopy in patients with anomalous kidneys can be technically challenging, advancements in endourological techniques have made it a safe and effective procedure. In these patients the stone-free rates are good with a low risk of major complications.

[High ureteral insertion as the cause of extreme hydronephrosis in a 5-year-old child with horseshoe kidney]

The incidence of horseshoe kidney is 1 per 400-800 live births. From 44-52% of the patients with horseshoe kidney have other coexisting abnormalities of the urinary tract, such as hydronephrosis, vesicoureteral reflux and a duplex collecting system. Our patient, a 5-year old boy, was admitted to a pediatric nephrology department because of abdominal pain and vomiting. He had ultrasonography of the abdomen performed for the first time at the age of 9-months and horseshoe kidney was shown. In a control ultrasonography, a mild dilatation of the pyelocalyceal system in the left kidney was described. On the day of admission, an abdominal ultrasound confirmed horseshoe kidney with large left hydronephrosis. Power Doppler ultrasonography showed two renal arteries to the left kidney and no arterial compression on the ureter. Dynamic scintigraphy (99mTc-EC) revealed left-sided hydronephrosis with high isotope intake up to 55% ERPF, a prolonged time of tissue perfusion and signs of subpelvic junction obstruction. Magnetic resonance urography presented an enlarged left kidney, with a diameter of up to 105 mm, a narrow renal cortex, a dilated renal pelvis up to 39 mm in diameter, dilated calyces up to 26-32 mm, and the high insertion of the ureter from the pelvis. The right kidney was normal. To facilitate drainage from the dilated collecting system of the left kidney, a double-J catheter was inserted. Pyeloplasty is planned as the next step of treatment. Conclusion: In a child with horseshoe kidney and a mild dilatation of the collecting system detected in infancy, long-term follow up is necessary, because of the increased risk of significant hydronephrosis in the future.

Nephrolithiasis in a 17-Year-Old Male With Seckel Syndrome and Horseshoe Kidneys: Case Report and Review of the Literature

We report the case of a 17-year-old male with Seckel syndrome and horseshoe kidneys which had a 7 mm kidney stone in the lower pole calyx of the right moiety. The patient had a history of rotoscoliosis with 60° dextroconvex curvature and hepatic steatosis. Attempted ureteroscopy was unsuccessful due to stone location and anatomy. Percutaneous nephrolithotomy was ultimately required. This case highlights the difficulties of endoscopic treatments of renal calculi in patients with abnormal renal anatomy and dysmorphia. To our knowledge, this is the first reported case of nephrolithiasis in a patient with Seckel syndrome and horseshoe kidneys.