Evaluation of the duration of ureteral stenting following endopyelotomy: Animal study

Establishment of an artificial urine model in vitro and rat or pig model in vivo to evaluate urinary crystal adherence

The current study aimed to establish an experimental model in vitro and in vivo of urinary crystal deposition on the surface of ureteral stents, to evaluate the ability to prevent crystal adhesion. Non-treated ureteral stents were placed in artificial urine under various conditions in vitro. In vivo, ethylene glycol and hydroxyproline were administered orally to rats and pigs, and urinary crystals and urinary Ca were investigated by Inductively Coupled Plasma-Optical Emission Spectrometer. in vitro, during the 3- and 4-week immersion periods, more crystals adhered to the ureteral stent in artificial urine model 1 than the other artificial urine models (p < 0.01). Comparing the presence or absence of urea in the composition of the artificial urine, the artificial urine without urea showed less variability in pH change and more crystal adhesion (p < 0.05). Starting the experiment at pH 6.3 resulted in the highest amount of crystal adhesion to the ureteral stent (p < 0.05). In vivo, urinary crystals and urinary Ca increased in rat and pig experimental models. This experimental model in vitro and in vivo can be used to evaluate the ability to prevent crystal adhesion and deposition in the development of new ureteral stents to reduce ureteral stent-related side effects in patients.

Urinary Stent Development and Evaluation Models: In Vitro, Ex Vivo and In Vivo-A European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS) Initiative

Background: When trying to modify urinary stents, certain pre-clinical steps have to be followed before clinical evaluation in humans. Usually, the process starts as an in silico assessment. The urinary tract is a highly complex, dynamic and variable environment, which makes a computer simulation closely reflecting physiological conditions extremely challenging. Therefore, the pre-clinical evaluation needs to go through further steps of in vitro, ex vivo and in vivo assessments. Methods and materials: Within the European Network of Multidisciplinary Research to Improve Urinary Stents (ENIUS), the authors summarized and evaluated stent assessment models in silico, in vitro, ex vivo and in vivo. The topic and relevant sub-topics were researched in a systematic literature search in Embase, Scope, Web of Science and PubMed. Clinicaltrials.gov was consulted for ongoing trials. Articles were selected systematically according to guidelines with non-relevant, non-complete, and non-English or Spanish language articles excluded. Results: In the first part of this paper, we critically evaluate in vitro stent assessment models used over the last five decades, outlining briefly their strengths and weaknesses. In the second part, we provide a step-by-step guide on what to consider when setting up an ex vivo model for stent evaluation on the example of a biodegradable stent. Lastly, the third part lists and discusses the pros and cons of available animal models for urinary stent evaluation, this being the final step before human trials. Conclusions: We hope that this overview can provide a practical guide and a critical discussion of the experimental pre-clinical evaluation steps needed, which will help interested readers in choosing the right methodology from the start of a stent evaluation process once an in silico assessment has been completed. Only a transparent multidisciplinary approach using the correct methodology will lead to a successful clinical implementation of any new or modified stent.

Factors affecting the effectiveness and success of retrograde holmium laser endopyelotomy as the primary treatment of ureteropelvic junction obstruction in adults

PURPOSE

To evaluate the factors affecting the effectiveness, safety, and success of retrograde holmium:yttrium-aluminum-garnet laser endopyelotomy as the primary treatment of ureteropelvic junction obstruction in adults.

METHODS

Adult patients who underwent retrograde holmium:yttrium-aluminum-garnet laser endopyelotomy as the primary treatment of ureteropelvic junction obstruction between January 2012 and June 2016 at our clinic were retrospectively analyzed. Success was defined as the relief of symptoms and the resolution of obstruction, as assessed via radiography. Factors affecting success were analyzed, such as the clinical characteristics, procedural outcomes, complications, and the type of ureteroscopy used in the procedure.

RESULTS

Procedural success was achieved in 29 (74.4%) out of 39 patients, with a mean age of 38.3 ± 12.3 years during a median follow-up duration of 44 (33-65) months. Failure occurred at a median of 4.5 (3-22) months. It was detected that the presence of primary obstruction, ipsilateral kidney function being >30% of normal, and the length of obstruction being <1 cm positively affected procedural success (p = 0.009, p = 0.011, and p = 0.019, respectively). In the postoperative period, two Grade I and four Grade II complications were observed according to the Clavien-Dindo classification. There was a difference only in the operation time between semirigid (24) and flexible ureteroscopes (15), with the operation time being shorter with the use of a semirigid ureteroscope than with the use of a flexible uteroscope (p < 0.001).

CONCLUSION

Retrograde holmium:yttrium-aluminum-garnet laser endopyelotomy is a minimally invasive method that can be used effectively and safely as the primary treatment of patients with ureteropelvic obstruction, when long-term results are also taken into consideration. The decision of performing laser endopyelotomy should be made after a detailed evaluation of the characteristics of the patient as well as of the obstruction.

Laser Endopyelotomy in the Management of Pelviureteric Junction Obstruction in Adults: A Systematic Review of the Literature

Laser endopyelotomy (LEP) is considered as an option for the treatment of pelviureteric junction obstruction in adults. A comprehensive systematic search of the published literature was performed to assess the success rate and perioperative complications of LEP in the treatment of primary and secondary pelviureteric junction obstruction and to identify the factors that may have an impact on the success of LEP. The evidence available has significant limitations in terms of the heterogeneous study design and the definitions of outcomes. The average overall success rate of the pooled data was 75% with a mean follow-up of 29 months. Complications were predominately minor with an average rate of 12.5%.

Postureteroscopic lesion scale: a new management modified organ injury scale--evaluation in 435 ureteroscopic patients

BACKGROUND AND PURPOSE

Objective parameters for the classification of ureteral injuries and resulting indications for ureteral stent placement after ureteroscopy are lacking. We hereby present a new classification system including proof of interrater reliability and validation of recommendations for postoperative ureteral stent placement.

PATIENTS AND METHODS

The Postureteroscopic Lesion Scale (PULS) was applied in 435 patients undergoing ureteroscopy. Interrater reliability between three surgeons (junior resident, senior resident, and specialist) was evaluated in 112 patients. Postoperative ureteral stent placement was performed according to PULS. For follow-up with ultrasonography, we assumed hydronephrosis to be an indirect sign for significant postoperative ureteral obstruction.

RESULTS

No ureteral lesion was seen in 46.2% of patients (grade 0). A grade 1, 2, or 3 lesion was seen in 30.8%, 19.1%, and 3.9% of patients, respectively. No grade 4 or 5 lesions were observed in our series. Interrater reliability was high (Kendall W=0.91; mean Spearman Rho=0.86). This was particularly true between senior resident and specialist (Rho=0.95), compared with junior resident and senior resident or specialist (Rho=0.83, Rho=0.79, respectively). All patients with documented lesions had a Double-J stent placed. Indwelling time varied according to PULS. Results of a postoperative ultrasonographic follow-up could be obtained in 95.6% of cases. No patient showed clinical or sonographic signs of upper urinary tract obstruction.

CONCLUSIONS

According to these preliminary data for the clinical application of PULS, interrater reliability is high. Standardized empiric recommendations for the use and duration of postoperative stent placement after ureteroscopy might be useful in guiding urologists in this conversely discussed issue, ultimately preventing ureteral strictures as a late complication of ureteroscopy. These will have to be confirmed, however, by controlled trials in the future.

Effectiveness of three-dimensional fluoroscopy in percutaneous nephrostomy: an animal model study

OBJECTIVES

To present, in an experimental study, an assessment of innovative digital fluoroscopy systems with three-dimensional (3D) reconstruction for use in endourologic applications.

METHODS

The experiment was performed in a pig model. We used 5 pigs. An obstructive uropathy model was created in the right kidney to dilate the urinary tract for group 1. Group 2 consisted of the nondilated left kidney. After selecting the tract on the 3D image, the lower caliceal group was punctured in the 2 kidneys under fluoroscopic control, to assess the efficiency of the 3D reconstruction when selecting the renal calix to be punctured.

RESULTS

The 3D reconstruction system allowed us to obtain reconstruct the pelvis in three dimensions, isolated as the pelvis and renal parenchyma, as well as the adjacent bony relationships. In this study, the success rate was 100% for locating the selected renal calix.

CONCLUSIONS

With this 3D reconstruction system, we were able to obtain a series of images that allowed for the study of the volume of the kidney, perfectly determining its renal calix distribution in the operating room. This enabled us to determine the precise delineation of the target calix. We, therefore, consider this new urologic application of fluoroscopy very useful in surgical planning for antegrade access of the upper urinary tract.

Reliability and validity of endoluminal sonography in a porcine model of ureteropelvic junction obstruction

PURPOSE

The objective of this study was to evaluate the usefulness and reliability of endoluminal ultrasonography in ureteropelvic junction (UPJ) obstruction and to describe the changes in sonographic appearance that take place during obstruction and after treatment.

MATERIALS AND METHODS

Twelve large healthy white female pigs were randomly divided into two groups: Group 1 (laparoscopic pyeloplasty) and group 2 (cutting balloon endopyelotomy). Percutaneous and endoluminal ultrasonographic and fluoroscopic studies were analyzed during the three phases of the study. The first phase included premodel documentation of a normal urinary tract and laparoscopic UPJ obstruction. During the second phase 6 weeks later, diagnosis and endourologic treatment were performed. Fifteen weeks after obstruction management, follow-up imaging studies and postmortem evaluation of all animals were performed.

RESULTS

At the end of the study, group 1 had a lesser degree of fibrosis in the muscle-adventitia layers and periureteral repercussion, as well as a better peristaltic recovery. The animal study shows a positive correlation among the results of the pathologic and the endoluminal ultrasonographic studies in UPJ obstruction.

CONCLUSIONS

Endoluminal ultrasonography provides excellent information regarding ureteral and periureteral anatomy. Among the two techniques evaluated in the study, laparoscopic pyeloplasty caused the lesser reaction at the reconstructed area. Fibrous replacement at the muscle-adventitia layers and periureteral area may be useful as indicators of the better therapeutic technique as well as for the assessment of post-therapeutic ureteral evolution and recurrences.