Dean NS. et al., 2023: Ureteral Wall Thickness (UWT) is an Effective Predictor of Ureteral Stone Impaction and Management Outcomes: A Systematic-Review and Meta-Analysis.
Dean NS, Millan B, Uy M, Albers P, Campbell SM, Krambeck AE, De S.J
Division of Urology, Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
Department of Urology, Northwestern University, Chicago, Illinois.
Division of Urology, Department of Surgery, McMaster University, Hamilton, Ontario, Canada.
John W. Scott Health Sciences Library, University of Alberta, Edmonton, Alberta, Canada.
Purpose: Ureteral stone impaction is associated with unfavorable endourologic outcomes, however reliable predictors of stone impaction are limited. We aimed to assess the performance of ureteral wall thickness (UWT) on non-contrast computed tomography as a predictor of ureteral stone impaction and failure rates of spontaneous stone passage, shockwave lithotripsy, and retrograde guidewire and stent passage.
Methods: This study was completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines (PRISMA). A search was conducted in April 2022 for all adult, human and English language studies investigating UWT using PROSPERO, OVID Medline, OVID EMBASE, Wiley Cochrane Library, Proquest Dissertations and Theses Global and SCOPUS. A systematic review and meta-analysis using random effects model were conducted. Risk of bias was assessed using the MINORS score.
Results: Fourteen studies with a pooled population of 2987 patients were included for quantitative analysis and 34 studies were included in our qualitative review. Meta-analysis findings suggest that a thinner UWT is associated with more favorable subgroup stone outcomes. Thinner UWT suggests a lack of stone impaction and was associated with improved rates of spontaneous stone passage, successful retrograde guidewire and stent placement, and improved shockwave lithotripsy outcomes. Studies lack a standardized UWT measurement protocol.
Conclusions: UWT is a non-invasive measure that predicts ureteral stone impaction and thin measurements are predictive of successful outcomes. Variability in measurement methods confirms that a standardized UWT protocol is needed, and the clinical utility of UWT is yet to be determined.
Urol. 2023 May 26:101097JU0000000000003561. doi: 10.1097/JU.0000000000003561. Online ahead of print.PMID: 37232694
One factor considered of great importance for failed SWL and endourological procedures is stone impaction. Because a strict definition usually is lacking, “stone impaction” in many cases is a subjective rather than objective conclusion.
The general impression is that in case of impaction the stone is surrounded by an edematous ureter associated with inflammation which cause thickness of the ureter. It has been observed that an increased ureteral wall thickness (UWT) thus combines edema of the ureteral mucosa, interstitial fibrosis, and hypertrophy of the muscularis layer.
In the meta-analysis presented by the authors, successful MET was associated with mean SWT-thickness of -1.38 mm and successful SWL -1.84 mm.
Although the results clearly show that UWT is an important variable for stone passage, stent passage and SWL success, it was not possible to define more precisely how UWT measures should be interpreted. This is indeed disappointing, but as could be expected, the bottom-line is that a thin UWT is favorable and a thick UWT is unfavorable!
One point that certainly needs more attention is how long the stone has remained in the ureter and which manipulations that have been carried out. The importance of the latter factors is emphasized by the fact that SWL of ureteral stones is improved by short interval between the acute episode and treatment.