Handling and prevention of complications in stone basketing

Mechanical characteristics of the ureter and clinical implications

The ureteric wall is a complex multi-layered structure. The ureter shows variation in passive mechanical properties, histological morphology and insertion forces along the anatomical length. Ureter mechanical properties also vary depending on the direction of tensile testing and the anatomical region tested. Compliance is greatest in the proximal ureter and lower in the distal ureter, which contributes to the role of the ureter as a high-resistance sphincter. Similar to other human tissues, the ureteric wall remodels with age, resulting in changes to the mechanical properties. The passive mechanical properties of the ureter vary between species, and variation in tissue storage and testing methods limits comparison across some studies. Knowledge of the morphological and mechanical properties of the ureteric wall can aid in understanding urine transport and safety thresholds in surgical techniques. Indeed, various factors alter the forces required to insert access sheaths or scopes into the ureter, including sheath diameter, safety wires and medications. Future studies on human ureteric tissue both in vivo and ex vivo are required to understand the mechanical properties of the ureter and how forces influence these properties. Testing of instrument insertion forces in humans with a focus on defining safe upper limits and techniques to reduce trauma are also needed. Last, evaluation of dilatation limits in the mid and proximal ureter and clarification of tensile strength anisotropy in human specimens are necessary.

A magnetic hydrogel for the efficient retrieval of kidney stone fragments during ureteroscopy

Only 60-75% of conventional kidney stone surgeries achieve complete stone-free status. Up to 30% of patients with residual fragments <2 mm in size experience subsequent stone-related complications. Here we demonstrate a stone retrieval technology in which fragments are rendered magnetizable with a magnetic hydrogel so that they can be easily retrieved with a simple magnetic tool. The magnetic hydrogel facilitates robust in vitro capture of stone fragments of clinically relevant sizes and compositions. The hydrogel components exhibit no cytotoxicity in cell culture and only superficial effects on ex vivo human urothelium and in vivo mouse bladders. Furthermore, the hydrogel demonstrates antimicrobial activity against common uropathogens on par with that of common antibiotics. By enabling the efficient retrieval of kidney stone fragments, our method can lead to improved stone-free rates and patient outcomes.

Using spatial-temporal ensembles of convolutional neural networks for lumen segmentation in ureteroscopy

Purpose

Ureteroscopy is an efficient endoscopic minimally invasive technique for the diagnosis and treatment of upper tract urothelial carcinoma. During ureteroscopy, the automatic segmentation of the hollow lumen is of primary importance, since it indicates the path that the endoscope should follow. In order to obtain an accurate segmentation of the hollow lumen, this paper presents an automatic method based on convolutional neural networks (CNNs).

Methods

The proposed method is based on an ensemble of 4 parallel CNNs to simultaneously process single and multi-frame information. Of these, two architectures are taken as core-models, namely U-Net based in residual blocks (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$m_1$$\end{document}m1) and Mask-RCNN (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$m_2$$\end{document}m2), which are fed with single still-frames I(t). The other two models (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$M_1$$\end{document}M1, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$M_2$$\end{document}M2) are modifications of the former ones consisting on the addition of a stage which makes use of 3D convolutions to process temporal information. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$M_1$$\end{document}M1, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$M_2$$\end{document}M2 are fed with triplets of frames (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$I(t-1)$$\end{document}I(t-1), I(t), \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$I(t+1)$$\end{document}I(t+1)) to produce the segmentation for I(t).

Results

The proposed method was evaluated using a custom dataset of 11 videos (2673 frames) which were collected and manually annotated from 6 patients. We obtain a Dice similarity coefficient of 0.80, outperforming previous state-of-the-art methods.

Conclusion

The obtained results show that spatial-temporal information can be effectively exploited by the ensemble model to improve hollow lumen segmentation in ureteroscopic images. The method is effective also in the presence of poor visibility, occasional bleeding, or specular reflections.

Supplementary Information

The online version supplementary material available at 10.1007/s11548-021-02376-3.

Stone size on endoscopic view as a predictor of successful stone retrieval during flexible ureteroscopy: an in vitro analysis

PURPOSE

Basketing plays an important role during flexible ureteroscopy, but it can be time-consuming, especially when fragments are too large to pass through the ureteral access sheath. We aim to present the optimal on-screen, endoscopic stone size that predicts successful basketing through various access sheaths.

METHODS

A tipless basket, individually extended to 5 mm from multiple ureteroscopes: (Flex-Xc, Karl Storz; Flex-X2s, Karl Storz; LithoVue, Boston Scientific; or URF-P6R, Olympus) and via differently sized access sheaths (10-12 Fr through 13-15 Fr), was used in retrieval attempts of various artificial stone sizes (2 mm through 5 mm). A relative endoscopic stone size was recorded as the stone's maximum diameter on endoscopic view compared to the total image diameter.

RESULTS

Basketing of stones up to 2.5 mm, yielding relative endoscopic stone sizes of 0.38 (Flex-Xc), 0.30 (Flex-X2s), 0.32 (LithoVue), and 0.34 (URF-P6R), was successful using all access sheaths. Only the 12-14 Fr and greater sheaths allowed for successful basketing of 3 mm stones. Larger stones did not successfully pass through any of the access sheaths.

CONCLUSION

Successful stone retrieval can be predicted by estimating the stone's size on screen, which is influenced by the type of flexible ureteroscope and access sheath. In our testing, stones of approximately one-third of the screen size passed successfully in all cases.

Case report series: management of complete ureteral avulsion with review of the relevant literature

Background

Endoscopic operations and ureteroscopy have become the first choice for ureteral calculi and ureter-related operations. The ratios of the complications, which are mostly iatrogenic, range between 9 and 11%. Total ureteral avulsion during URS is quite rare with a prevalence of 0–0.3%. We present three total ureteral avulsions we experienced in our clinic during the last 2 years and their treatment.

Case presentation

During the last 2 years, we experienced three total ureteral avulsions: one of these occurred in our clinic and the other two occurred in an external center and were referred to us. In two cases, the omental flap was rotated after ureteral reimplantation and the ureter was completely wrapped inside the omental flap. In the third case, boari flap was formed from the bladder. Due to the presence of extrarenal wide renal pelvis, anastomosis was made with boari flap after a y–v flap was rotated on the renal pelvis. D-J stents of the patients were removed at the end of 3 months. Although there was mild hydronephrosis, parenchymal thinning and a significant decrease in functions were not observed. Ureteral avulsion of the patients was successfully managed without the need for nephrectomy.

Conclusion

Ureteral avulsion management is an extremely difficult condition for both the surgeon and the patient. So, the most important thing is to prevent ureteral avulsion. Ureteroplasty and omental flap treatment are applicable methods with quite successful results for complete ureteral avulsions.

Broken basket conundrum

Background

Broken basket during retrograde intrarenal surgery (RIRS) is a known complication. The literature regarding this common complication is limited. We report a case of broken basket and explain the technique by which we retrieved the broken basket fragment that was entrapped around the calculus. We also analyze at the prevention strategies and better management strategies.

Case presentation

A 62-year-old male underwent RIRS for a 2-cm right renal lower calyceal calculus. A tipless nitinol stone basket got broken and distal part got entrapped around the calculus when basketing was attempted. We proceeded with stone fragmentation by RIRS. After complete stone fragmentation, another tipless nitinol stone basket was used to grab the broken tip of distal basket fragment which was lying in the renal pelvis. The broken basket fragment could be retrieved out in toto.

Conclusions

Basketing large lower calyceal calculus should be attempted with caution. Partial or complete fragmentation of large calculus is preferable before basketing attempt. If the calculus is entrapped rather than forceful pulling, cutting the basket proximally near to the handle, followed by stone fragmentation, could minimize complications. Locating the broken tip of the basket fragment and grasping it makes the retrieval easier and safer.

Retrograde ureteroscopy in the management of distal ureteric stones: A retrospective analysis of outcome and complications

Background

Urinary stones affect 8%-15% of the world population. In Nigeria, contemporary reports have shown that the incidence of urinary stones is rising. The distal ureter has been described as the most common location of ureteric stones. This study seeks to review our experience in the ureteroscopic management of distal ureteric stones with a view to appraising the stone clearance rate and the complications seen in our patients.

Patients and Methods

This descriptive study reviewed the record of 21 patients, who had semirigid ureteroscopy and pneumatic lithotripsy for distal ureteric stone between October 2015 and September 2018. All patients had computed tomography urography preoperatively to locate the stone. Data on patients' demographics, indication for the surgery, location and size of stone, preoperative double-J (DJ) placement, postoperative DJ stent placement, intraoperative and postoperative complications, and status of stone clearance were retrieved and subjected to statistical analysis.

Results

The mean age of the patients was 37.95 ± 11.09 (range, 21-67) years. The mean stone size was 8.06 ± 2.87 mm with a range of 4.8 mm-15.0 mm. Out of the 21 patients, 20 (95.2%) had the procedure for recurrent ureteric colic and 1 (48%) was for hematuria. Four (19.0%) patients had DJ stent preoperatively, whereas 17 (81.0%) patients did not have. Fourteen (66.7%) patients had intraoperative ureteric dilatation. Postoperative DJ stent was placed in 17 (81.0%) patients, whereas 4 (19.0%) patients did not have. Three (14.3%) patients had mucosal flap, 6 (14.3%) had mucosal abrasion, 2 (9.5%) had bleeding, 1 (4.8%) patient had transient hematuria postoperatively, and 2 (9.5%) patients had urinary tract infection. Nineteen (90.5%) patients had complete clearance in a single surgery. Two (9.5%) patients had symptomatic residual fragments that required repeat ureteroscopy.

Conclusion

Our study has shown that ureteroscopy is a useful and safe technique in the removal of stones in distal ureter.

Operator-assisted vs self-achieved basketing during ureteroscopy: results from an in vitro preference study

OBJECTIVES

A recently introduced device (LithoVue Empower™ or LE, Boston Scientifics, USA) allows the surgeon to directly control the stone-retrieving basket without the need of an assistant during flexible ureteroscopy. We aimed to evaluate the stone-retrieval performance of this device.

METHODS

We used a bench-training model for flexible ureteroscopy, the Key-box (K-Box®, Porgès-Coloplast, France), to compare the LE configured with a 1.9F stone-retrieval tipless basket (ZeroTip™, Boston Scientific, USA) and a traditional assistant-maneuvered 1.9F stone-retrieval tipless basket. Seven experienced endo-urologists and seven residents-in-training retrieved a fake stone from three different renal cavities of the K-Box with increasing access complexity first with the traditional basket and then with the LE device. We recorded retrieval time and all the operators filled in the NASA Task Load Index (TLI) for the self-evaluation of their performance. We then compared the use of LE in terms of retrieval time, failure rates, and NASA-TLI scores.

RESULTS

Stone retrieval times and failure rates were similar according to the retrieval technique, although residents had non-statistically significant shorter times with the LE. NASA-TLI scores revealed lower frustration (p = 0.03) when LE was used by experienced urologists as compared to the traditional basketing. When stratifying the analyses according to surgical experience, fully trained urologists performed faster stone retrieval and showed lower effort scores than residents-in-training (p < 0.05).

CONCLUSIONS

The individually controlled retrieval system is an effective device assisting stone retrieval and does not necessitate specific training among experienced endo-urologists. Young residents might benefit from LE during their learning curve.

Adult iatrogenic ureteral injury and stricture-incidence and treatment strategies

Iatrogenic ureteral injuries and strictures are relatively common complication of pelvic surgery and radiation treatment. Left untreated they are associated with severe short- and long-term complications such as urinoma, septic state, renal failure, and loss of a renal unit. Treatment depends on timing of diagnosis, as well as extent of injury, and ranges from simple endoscopic management to complex surgical reconstruction under usage of pedicled grafts. While recent advances in ureteral tissue engineering are promising the topic is still underreported. Historically a domain of open surgery, laparoscopic and robotic-assisted approaches have proven their feasibility in small case series, and are increasingly being utilized as means of reconstructive surgery. This review aims to give an outline of incidence and treatment of ureteral injuries and strictures in light of the latest advances.

Laparoscopic ureteroneocystostomy for mid and lower ureteric strictures: Experience from a tertiary center

Purpose:

The purpose of this study is to evaluate our experience of laparoscopic ureteroneocystostomy for mid and lower ureteral stricture in a tertiary center in North India.

Materials and Methods:

A total of 20 laparoscopic ureteroneocystostomy were performed with or without bladder flap procedures in 20 patients (13 females and 7 males) with various etiologies such as ureteric stricture, ureterovaginal fistula, endometriosis, and distal ureteric tumor at our hospital in a time frame from August 2013 to January 2017. Eight cases each presented after laparoscopic/open hysterectomy and postureterorenoscopic stone removal while two cases each presented secondary to endometriosis and distal ureteric tumor. Simple laparoscopic ureteroneocystostomy in 4, psoas hitch in 9, and Boari flap was done in 7 cases.

Results:

The mean patient age was 44.2 years (range 19–65), mean surgical time was 184.25 min (115–250 min.), mean amount of bleeding was 153.25 mL (90–250 mL), and mean hospital stay was 3.05 days (2–7 days). Female-to-male ratio was 1.3:0.7. There was one conversion to open during laparoscopic Boari reimplant because of inadvertent injury to external iliac vein. The mean follow-up was 22.35 months (6–45). All the patients were asymptomatic with the resolution of hydronephrosis on ultrasound and without any significant obstruction on renal scan.

Conclusions:

Laparoscopic ureteroneocystostomy with or without bladder flap (Boari) provides good functional outcomes with excellent success rates and minimal morbidity comparable to open surgery in patients with ureteric stricture.

A prospective multicenter European study on flexible ureterorenoscopy for the management of renal stone

Purpose

The aim of this study was to describe the outcomes and the complications of retrograde intrarenal surgery (RIRS) for renal stones in a multi-institutional working group.

Materials and Methods

From 2012 to 2014, we conducted a prospective study including all RIRS performed for kidney stones in 4 European centers. Demographic information, disease characteristics, and perioperative and postoperative data were gathered. Patients and stone data, procedure characteristics, results and safety outcomes were analyzed and compared by descriptive statistics. Complications were reported using the standardized Clavien system.

Results

Three hundred and fifty-six patients underwent 377 RIRS with holmium laser lithotripsy for renal stones. The RIRS was completed in all patients with a mean operative time of 63.5 min. The stone-free status was confirmed endoscopically and through fluoroscopic imaging after the first procedure in 73.6%. The second procedure was performed in twenty patients (5.6%) achieving an overall stone free rate of 78.9%. The overall complication rate was 15.1%. Intra-operative and post-operative complications were seen in 24 (6.7%) and 30 (8.4%) cases, respectively.

Conclusions

RIRS is a minimally invasive procedure with good results in terms of stone-free and complications rate.

Evaluation of ureteroscopy outcome in a teaching hospital

OBJECTIVE

To evaluate factors affecting semi-rigid ureteroscopy (URS) results highlighting the influence of teaching on its outcomes.

MATERIAL AND METHODS

We reviewed the files of 891 adult patients who had undergone 1182 ureteroscopies at our institute during the period from July 2008 to June 2011. The outcomes of all URSs were evaluated. Outcomes were measured by stone- free rate and presence of complications, which were assessed using the Clavien-Dindo system. Patients were divided into 2 groups; Group 1 (favorable outcome) became stone- free after the first URS and had no documented complications, while Group 2 (unfavorable outcome) had residual stones and/or complications. Group 2 was subdivided according to the skill level of the operating surgeon into two subgroups. Patients belonging to subgroup A had their procedures performed by urology trainees under direct supervision of expert urologists, while those in subgroup B had their procedures performed by the expert urologists themselves. All groups were compared using univariate (chi-square and t tests) and multivariate (logistic regression) statistical tests to identify significant risk factors. All data was analyzed using SPSS.

RESULTS

A total of 1182 URSs were evaluated. 958 patients had a favorable outcome (Group 1) while 224 patients had an unfavorable outcome (Group 2). Factors associated with an unfavorable outcome include location of the presenting stone (p<0.001) and presence of stone impaction (p<0.001). No statistically significant differences were detected in the overall complication rate between trainees and expert urologists. Trainees stone- free rate was comparable to that of experts; 90.3% vs. 91.1%, respectively, p=0.6.

CONCLUSION

Factors such as stone impaction and proximal location are associated with an unfavorable surgical outcome. In a high- volume teaching hospital, semi-rigid URS done by trainees under direct supervision is safe and their outcome is comparable to literature findings.

The surgical experience influences the safety of retrograde intrarenal surgery for kidney stones: a propensity score analysis

The aim of this study is to evaluate if surgical experience could influence the outcomes of retrograde intrarenal surgery (RIRS) in terms of stone clearance and complication rate. Patients from five institutions were included in this study. Patients were divided into two groups. Group 1: patients treated by three surgeons in the early phase of learning curve (surgical experience <100 procedures); Group 2: cases operated by two surgeons with great endourological experience (>400 procedures). Patients and stone characteristics, outcome and complications were analyzed. Multivariable regression model was used. Differences between groups were estimated using propensity scores to adjust for the bias inherent to the different characteristics. 381 RIRS were analyzed (Group 1: 150 RIRS; Group 2: 231 RIRS). Clinical data and stone parameters were comparable. The SFR was 70 % in Group 1 and 77.9 % in Group 2 (p = 0.082). Operative time was significantly shorter in the Group 2 (76.3 vs. 53.1 min, p = 0.001). The overall complication rate was significantly lower in Group 2 (20.7 vs. 8.7, p = 0.001). At unadjusted analysis, a non-significant difference was found between centers on SFR (OR 1.51 95 % CI 0.95-2.41). Conversely, a significant difference was found on overall complications (OR 0.36 95 %CI 0.20-0.67) with lower overall complication in Group 2. This study shows that surgeon experience influences the outcomes of RIRS mainly in terms of safety. Further studies will be needed to assess the exact number of procedures necessary to obtain a plateau in the rate of complications and success.

Evaluation of the tensile strength of the human ureter--preliminary results

BACKGROUND AND PURPOSE

Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter and, of those, none has determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter.

METHODS

We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or nonfunctioning kidney. The specimens were then cut into multiple circumferentially and longitudinally oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens.

RESULTS

The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm(-2) and 902.43±122.08 Ncm(-2), respectively (P<0.001). The circumferential strength in the proximal portion of the ureter was 409.89±35.13 Ncm(-2) in comparison with 502.89±55.85 Ncm(-2) in the distal portion (P=0.08).

CONCLUSIONS

The circumferential tensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators to prevent complications.

Significance of Extraction Forces in Kidney Stone Basketing

INTRODUCTION

Ureteroscopic stone extraction devices are effective tools in the management of urolithiasis, but on occasion, their improper use can cause injury to the ureter. Avulsion and perforation of the ureter as a result of excessive forces on the extraction device are some of the more serious complications of this treatment.

MATERIALS AND METHODS

In this article, avulsion and perforation forces were measured by two different test setups. Eleven clinicians were asked to apply three ranges of forces (safe, cautious, and dangerous).

RESULTS

The output force measurements were recorded and plotted for further analysis. The maximal average perforation forces were 7.13±2.36 N in the benchtop tests and 7.07±2.20 N in the ex-vivo porcine tests (P=0.54). The maximal average avulsion forces were measured to be 10.14±2.01 N in the benchtop tests. Although the average forces were similar in the proximal and distal parts of the ureter (P=0.27), higher values were recorded for the distal part. The operative time was noted to be significantly different in the safe and cautious force regions (P=0.006). The average forces were higher in the benchtop tests compared with the porcine ureter tests. The extraction forces were measured and were noted to be significantly different for attending physicians and residents. The results suggest the need for force feedback training for residents.

CONCLUSION

The findings can be used to design a "smart device" that can provide visual force feedback to clinicians while they are operating, leading to improved patient outcome.

Management of iatrogenic ureteral injury

Iatrogenic injury to the ureter is a potentially devastating complication of modern surgery. The ureters are most often injured in gynecologic, colorectal, and vascular pelvic surgery. There is also potential for considerable ureteral injury during endoscopic procedures for ureteric pathology such as tumor or lithiasis. While maneuvers such as perioperative stenting have been touted as a means to avoid ureteral injury, these techniques have not been adopted universally, and the available literature does not make a case for their routine use. Distal ureteral injuries are best managed with ureteroneocystostomy with or without a vesico-psoas hitch. Mid-ureteral and proximal ureteral injuries can potentially be managed with ureteroureterostomy. If the distal segment is unsuitable for anastomosis then a number of techniques are available for repair including a Boari tubularized bladder flap, transureteroureterostomy, or renal autotransplantation. In rare cases renal autotransplantation or ureteral substitution with gastrointestinal segments may be warranted to re-establish urinary tract continuity. Laparoscopic and minimally invasive techniques have been employed to remedy iatrogenic ureteral injuries.

Metallic stents in the management of ureteric strictures

Management of ureteric strictures is a challenging task. Subtle presentation, silent progression and complex aetiology may delay diagnosis. A wide range of available treatment options combined with the lack of adequate randomised trials has led to the introduction of personal bias in the management of this difficult group of patients. Metallic ureteric stents offer an alternative to the conventional treatment modalities. A review of the currently available metallic stents and their role in the long-term management of ureteric strictures is presented. Materials used in the manufacture of indwelling urological devices are evolving all the time. Improved endo-urological techniques combined with new devices made from better compounds will continue to improve patient experience.

How to manage total avulsion of the ureter from both ends: our experience and literature review

OBJECTIVES

To evaluate the treatment alternatives of total avulsion of the ureter from both ends including ureteropelvic junction (UPJ) and ureterovesical junction (UVJ).

METHODS

Total ureteral avulsion on both ends of the ureter was examined in 4 cases performing ureteroscopy. In two male patients of the four cases, avulsion was noticed intraoperatively and ureteral re-anastomosis at UPJ and re-implantation at UVJ were performed immediately. Boari flap was performed for one female patient immediately and for the other female patient who was referred from another hospital after the ureteroscopy, 4 days later.

RESULTS

One patient who had ureteral re-implantation was followed with 3-month intervals by ultrasonography and abdominal X-ray. At the end of 1 year, it was determined that kidney parenchyma was normal and the patient had kidney and upper ureteral stones. Percutaneous nephrolithotomy was performed, and the patient was stone-free at the end of the operation. Two years after the surgery, both kidneys were normal. This is the only case who had a successful ureteral re-implantation in literature. The other patient turned up a year later for routine checks after the ureteral stent was removed. Then, hydronephrosis and renal atrophy were detected. The patient did not accept nephrectomy or any other intervention and he was lost to follow-up. Boari flap procedure was performed after UPJ repair for the other two female patients. Their kidneys were both normal 3 months after the operation.

CONCLUSIONS

In case of ureteral avulsion from both ends of the ureter in the male patients, as bladder capacity is not enough for a Boari flap, proximal anastomosis and distal re-implantation could be a good choice for the management of this untoward event. This new approach also saves time for reconstructive treatments if necessary. If bladder capacity is enough to reach UPJ, Boari flap could be a good choice in female patients.

The ureteroscope as a safety wire for ureteronephroscopy

BACKGROUND AND PURPOSE

The recent technologic advances in the newer generation of flexible ureteroscopes have significantly enhanced the therapeutic and diagnostic efficacy of ureteroscopy. The purpose of our study was to assess ureteroscopy and lithotripsy of renal calculi without a safety wire, using the ureteroscope as the safety device.

PATIENTS AND METHODS

Medical records for patients undergoing ureteroscopy by a single surgeon were retrospectively reviewed from December 2006 to December 2009. Inclusion criteria for our study included all adult patients who underwent wireless flexible ureteroscopy for the management of renal calculi and had 1 month follow-up data.

RESULTS

Of the 568 patients who underwent ureteroscopy during this period, 268 patients met our study inclusion criteria. The mean age of the patients undergoing wireless ureteroscopy was 33 years, and the mean body mass index was 33.1 kg/m(2). Mean stone diameter of the renal calculi treated was 12.0±5.9 mm. Fifteen percent of the patients had a ureteral stent in place before the procedure, and 84% of the patients had a stent placed after ureteroscopy. Twenty percent of the patients needed ureteral dilation, and 15% of the patients had a ureteral access sheath placed intraoperatively. The overall complication rate was 2.6% (major=0.7%, minor=1.9%). Complications included: Four urinary tract infections, two patients with urosepsis, and one patient with urinary retention. No patients had ureteral perforation or ureteral avulsion.

CONCLUSIONS

Using the ureteroscope as the safety mechanism, ureteroscopy is safe with regard to maintaining renal access and control. Routine safety wires during ureteronephroscopy are not necessary assuring the ureteroscope is in the kidney.

Ureterorenoscopy: avoiding and managing the complications

Retrograde exploration of the ureter and kidneys is currently a widely used and well-established procedure to deal with problems of a diagnostic and therapeutic nature with reduced invasiveness. The process of miniaturizing the instruments combined with the steady improvement in video quality has continuously amplified its potential applications, maintaining the procedure safe and rapid. During an operation, however, unexpected events may condition a change to the programme or determine the onset of even more serious complications. Our aim is to analyze such events and complications and recommend potential solutions to prevent and/or deal with such happenings.

Paclitaxel inhibits ureteral smooth muscle cell proliferation and collagen production in the absence of cell toxicity

PURPOSE

Urinary tract stricture results from excess collagen deposition at an injured area. Paclitaxel (Sigma-Aldrich®) prevents coronary artery restenosis by inhibiting vascular smooth muscle cell proliferation and collagen production. We evaluated the effects of paclitaxel on ureteral smooth muscle cell proliferation and collagen production.

MATERIALS AND METHODS

Three phases of experiments were done in canine smooth muscle cells. In phase 1 we used proliferation assay to study smooth muscle cells exposed to various concentrations of paclitaxel during 7 days. Phase 2 consisted of 6-day enzyme-linked immunosorbent assay to detect the total amount of type III collagen produced by smooth muscle cells exposed to paclitaxel. In phase 3 we assessed smooth muscle cell membrane damage using a lactate dehydrogenase cytotoxicity assay in which cells were exposed to escalating paclitaxel concentrations for 14 days.

RESULTS

Proliferation studies showed that 10 and 100 nM paclitaxel significantly inhibited ureteral smooth muscle cell proliferation. Enzyme-linked immunosorbent assay revealed significantly decreased type III collagen production at 100 nM. Cytotoxicity testing showed that 1 to 100 nM paclitaxel did not harm smooth muscle cells.

CONCLUSIONS

Paclitaxel effectively inhibits canine ureteral smooth muscle cell proliferation and collagen production without toxicity to smooth muscle cells at concentrations up to 100 nM. These results may ultimately translate into new methods of preventing and treating urinary stricture disease.

Rendering stone fragments paramagnetic with iron-oxide microparticles improves the efficiency and effectiveness of endoscopic stone fragment retrieval

OBJECTIVES

To develop peptide-coated iron oxide-based microparticles that selectively adhere to calcium stone fragments, thereby enabling magnetic manipulation of human stone fragments.

METHODS

In phase 1, human stone fragments were coated overnight with iron oxide-based microparticles. Groups of 10 coated stones (1.5-3 mm) were placed into a bladder simulator and removed cystoscopically with either an 8 Fr magnetic extraction device or a 2.4 Fr nitinol basket. In phase 2, the peptide coating was optimized and 2 stone fragment sizes (1-2 mm and 2-3 mm) were exposed to 3 separate concentrations of microparticles for 3 different incubation times. In each trial, 10 fragments were placed into a glass vial and removed using the 8 Fr magnetic device.

RESULTS

In phase 1, mean total time for removal of all fragments was 53% shorter using the magnetic instrument compared with basket extraction. An average of 3.7 extractions was required to magnetically remove all fragments versus 9.4 for basket extraction. In phase 2, 18 different combinations of particle concentrations, fragment sizes, and incubation times were tested; 91% of small fragment trials and 43% of large fragment trials yielded successful fragment extraction. Of the small fragments, 100% were successfully extracted at both the middle and high particle concentrations after 2 minutes, and of the large fragments 70% and 100% were successfully extracted after 10 minutes of incubation at the lowest and highest concentrations, respectively.

CONCLUSIONS

Rendering stone fragments paramagnetic with novel microparticles allows manipulation and removal using a novel magnetic device in vitro, potentially improving surgical efficacy and efficiency.

Ureteroscopic ultrasound technology to size kidney stone fragments: proof of principle using a miniaturized probe in a porcine model

PURPOSE

A prototype ultrasound-based probe for use in ureteroscopy was used for in vitro measurements of stone fragments in a porcine kidney.

METHODS

Fifteen human stones consisting of three different compositions were placed deep in the collecting system of a porcine kidney. A 2 MHz, 1.2 mm (3.6F) needle hydrophone was used to send and receive ultrasound pulses for stone sizing. Calculated stone thicknesses were compared with caliper measurements.

RESULTS

Correlation between ultrasound-determined thickness and caliper measurements was excellent in all three stone types (r(2) = 0.90, p < 0.0001). All 15 ultrasound measurements were accurate to within 1 mm, and 10 measurements were accurate within 0.5 mm.

CONCLUSION

A 3.6F ultrasound probe can be used to accurately size stone fragments to within 1 mm in a porcine kidney.

Stone Cone® in ureteroscopic ballistic lithotripsy of proximal ureteral stones

Stone Cone® (Microvasive-Boston Scientific Corp, USA) is a device which prevents retrograde calculus migration during endoscopic ureterolithotripsy. We have studied the safety and efficacy of this device in endoscopic ureterolithotripsy with ballistic energy in proximal ureteral stones.

Materials and Methods.

From 01/02/2006 to 01/02/2008 we carried out 36 ureterorenoscopies (URS) for proximal ureteral stones (average age: 46, range: 15–73). A ballistic energy was used for stones fragmentation. In 18 patients (Group A) we carried out URS with the aid of Stone Cone®, which was not used in the other 18 patients (Group B). Semirigid 8 Ch or 10 Ch Storz ureteroscope and ballistic lithotriptor Swiss Lithoclast Master EMS® were used. In cases of migration, edema, and ureteral damage, a ureteral stent was used.

Results.

In Group B patients (URS performed without Stone Cone®) the migration of the whole stone, or of clinically significant fragments, occurred 8 times (45%). All of these patients underwent external shockwave lithotripsy (ESWL) at a center equipped with a lithotriptor. A ureteral stent was placed in 14 cases (78%). In Group A, the migration of a stone requiring ESWL treatment occurred only once (5%). The ureteral stent was placed 8 times (45%). We had no significant complications during the procedure.

Conclusions.

The Stone Cone® is a safe and easy-to-use device. The cost of this device can be balanced by the reduction of postoperative ESWL treatments for lithiasic fragments pushing up into the kidneys (p<0.01), and of ureteral stent applications at the end of the procedure (p<0.05).

Endovascular snare kit in the combined antegrade and retrograde management of ureteral avulsion: report of two cases

We report the feasible and safe use of the Amplatz Goose Neck Snare kit for avulsed ureter retrieval during ureteroscopy. A 49-year-old lady and a 61-year-old man complaining of urolithiasis underwent ureteroscopy; following stone fragmentation, and basketing avulsion of the ureter occurred. Using the Amplatz Goose Neck Snare kit it was possible to place an indwelling ureteral catheter in both cases aiming at restoring the urinary upper tract continuity. The snare-assisted endovascular technique may be an interesting tool even in endourology for the management of ureteral avulsion. This endoscopic mini-invasive procedure makes it possible to avoid an immediate invasive surgical approach often resulting in nephrectomy, having time for planning a possible durable conservative treatment.

Evaluation of a new multi-basket load-release ureteral stent

INTRODUCTION

A multi-basket ureteral stent was tested and modified to assess feasibility of load-release features intended to release stone(s) if resistance is encountered during stent removal.

METHODS

Three versions of the stent were evaluated: (1) unaltered stent, (2) one strand of each basket partially cut to 50%, or 75% (3) tube between baskets longitudinally slit. One of the baskets was filled with multiple 3-4-mm stones or a single large 6-mm stone to 20Fr diameter. The force required to release the device through a tube with an 8Fr narrowing was determined. In a separate assessment, urologists used a string attached to the force gauge to exert the maximum force they would be comfortable using in ureteral stent removal.

RESULTS

The unaltered stent was associated with higher release forces or inability to remove the stent: 18.67 +/- 8.35 N when a single large stone was present, compared to 8.46 +/- 2.75 N for multiple small stones. Modified devices with 50% and 75% cut basket strands released at 15.19 +/- 1.54 N, and 10.65 +/- 2.09 N, respectively. The longitudinal slit device released at 3.11 +/- 1.57 N. The maximum force exerted by urologists in simulated stent removal was 7.3 +/- 0.4 N.

CONCLUSION

Modifications to the multi-basket ureteral stent allow for stent removal in an in vitro model with a narrowing present with stone(s) in the stent baskets. The longitudinal slit modification appears to allow for stent removal with forces low enough to prevent significant ureteral injury, even if ureteral strictures are present.