Yang SW. et al., 2021: Impact of Percutaneous Nephrostomy on the Efficacy of in Situ Shock Wave Lithotripsy for Upper Ureteral Stones.

Monday, 31 January 2022

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Yang SW, Lee JY, Shin JH, Lim JS, Song KH.
Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.

Abstract

Purpose: To investigate whether a Percutaneous nephrostomy (PCN) has any impact on the success rate of shock wave lithotripsy (SWL) and to estimate the probability of stone-free in SWL patients with upper ureter stones.

Materials and methods: Overall, 236 patients who underwent SWL for upper ureter stones between 2015 and 2019 were evaluated. Forty-nine patients who underwent PCN during SWL were identified. Medical data of the patients were retrospectively reviewed, and possible prognostic features were evaluated.

Results: Out of all patients, 147 patients were selected through propensity score matching. There were no significant differences between the PCN and no PCN groups, except for a lower stone-free rate (55.1% vs. 74.5%, p = .018) and one-session success rate (24.5% vs. 50.0%, p = .003) in the PCN group. In univariate analysis, a younger age, the female sex, a smaller size of stone, lower mean stone density (MSD), and absence of PCN were positive predictive factors of being stone-free in patients who underwent SWL. In multivariate analysis, a smaller size, lower MSD, and absence of PCN were positive predictive factors of being stone-free in patients who underwent SWL.

Conclusion: Stone size, MSD, and PCN were prognostic factors that influence the outcome of SWL. The presence of PCN during SWL is associated with adverse success rates in patients with upper ureter stones.
Urol J. 2021 Aug 14. doi: 10.22037/uj.v18i.6762. Online ahead of print. PMID: 34390249

Comments 1

Peter Alken on Monday, 31 January 2022 09:30

A good example for the difference between causal and coincidental relations.
The authors state : “We consider whether performing PCN to resolve the obstruction could improve the movement of the ureteral stone and increase the success rate of SWL. However, the findings did not support our expectations. Our results indicated that PCN insertions could adversely affect stone-free and one-session success during SWL.”
There are no arguments why insertion of a tube into the kidney could induce by itself a low ESWL success rate. The authors correctly mention the well-known factors that negatively influence the success of ESWL of ureteric stones like stone impactation, mucosal oedema, or thickness of the ureteric wall. They argued that drainage of urine could alleviate these conditions. However, they did into indicate who long urine was diverted to lead to positive changes of ureteral tissue and - most of all - it seems that the urine was diverted after ESWL. How could fragments pass down without fluid carrying them?

Peter Alken

A good example for the difference between causal and coincidental relations. 
The authors state : “We consider whether performing PCN to resolve the obstruction could improve the movement of the ureteral stone and increase the success rate of SWL. However, the findings did not support our expectations. Our results indicated that PCN insertions could adversely affect stone-free and one-session success during SWL.”
There are no arguments why insertion of a tube into the kidney could induce by itself a low ESWL success rate. The authors correctly mention the well-known factors that negatively  influence the success of ESWL of ureteric stones like stone impactation, mucosal oedema, or thickness of the ureteric wall. They argued that drainage of urine could alleviate these conditions. However, they did into indicate who long urine was diverted to lead to positive changes of ureteral tissue and - most of all - it seems that the urine was diverted after ESWL. How could fragments pass down without fluid carrying them?

Peter Alken

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