Assessment of the Grades of Vesicoureteral Reflux in Stented Ureters: An Experimental Study

Comparation of intraureteral stent and conventional stent at different stages: a systematic review with meta-analysis

INTRODUCTION

Stent related symptom (SRS) is the most common adverse effect of ureteral stenting. In recent years, many efforts have been made to develope modified ureteral stents to ameliorate SRS. It has been reported that intraureteral stents have the potential to improve the tail end adverse effect of the bladder and alleviate SRS. However, there still lack of evidence for the efficacy and the safety of clinically applying intraureteral stents. The aim of this work is to investigate the efficacy and safety of intraureteral stents.

EVIDENCE ACQUISITION

A systematic review was performed by using the PubMed, Web of Science, Medline, Embase, and Cochrane library. The studies published before February 2023 were included. The study selection was following the guideline from Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). The searching strategy was: "Pigtail suture stent" OR "Intra-ureteric stent" OR "Suture Stent" OR "Intraureteral stent" AND "Ureteroscopy" OR "Urinary calculi" OR "Stent-related symptoms" OR "Lower urinary tract symptoms". The data from randomized clinical trials which meet the selection criteria were extracted. Revman 5.4 was employed to proceed the meta-analysis.

EVIDENCE SYNTHESIS

A total of six randomized clinical trials of intraureteral stents were included in this systematic review and meta-analysis. According to the different investigation time, the results could be divided into four stages: early-stage, middle-stage, late-stage, and long-term evaluation. Urinary symptoms, pain score, and general health were significantly improved in intraureteral stents group at middle stage. For late-stage, intraureteral stent achieved better outcomes in urinary symptoms index, VAS score, quality of life, general health, and pain score. However, for early-stage and long-term evaluation, there was no significant difference between two groups.

CONCLUSIONS

This systematic review and meta-analysis reveal that regardless of the stage of treatment, the efficacy and safety of intraureteral stent are no worse than that of conventional stent. During 7-14 days postoperation, which is the most commonly time for clinically using ureteral stent, most of the outcomes of intraureteral stent are better than those of conventional stent. Hence, it is confirmed that intraureteral stent is worth for more clinical study and application.

An in vitro bladder model with physiological dynamics: Vesicoureteral reflux alters stent encrustation pattern

In vitro models are indispensable to study the physio-mechanical characteristics of the urinary tract and to evaluate ureteral stent performances. Yet previous models mimicking the urinary bladder have been limited to static or complicated systems. In this study, we designed a simple in vitro bladder model to simulate the dynamics of filling and voiding. The physio-mechanical condition of the model was verified using a pressure-flow test with different bladder outlet obstruction levels, and a reflux test was performed to qualitatively demonstrate the stent associated vesicoureteral reflux (VUR). Finally, the setup was applied with and without the bladder model to perform encrustation tests with artificial urine on commercially available double-J stents, and the volumes of luminal encrustations were quantified using micro-Computed Tomography and image segmentation. Our results suggest that, VUR is an important factor contributing to the dynamics in the upper urinary tract with indwelling stents, especially in patients with higher bladder outlet obstruction levels. The influence of VUR should be properly addressed in future in vitro studies and clinical analyses.