The “Guidewire-Coil”-Technique to prevent retrograde stone migration of ureteric calculi during intracorporeal lithothripsy
© The Author(s). 2017
Received: 23 October 2016
Accepted: 26 December 2016
Published: 5 January 2017
Stone retropulsion represents a challenge for intracorporeal lithotripsy of ureteral calculi. The consequences are an increased duration and cost of surgery as well as decreased stone-free rates. The use of additional tools to prevent proximal stone migration entails further costs and risks for ureteral injuries. We present the simple technique of using a coil of the routinely used guidewire to prevent stone retropulsion.
We retrospectively evaluated all patients with mid-to-proximal ureteral stones in 2014, which were treated by ureteroscopic lithotripsy (Ho: YAG and/or pneumatic lithotripsy). The preoperative stone burden was routinely assessed using low dose CT scan (if available) and/or intravenous pyelogram.
The study population consisted of 55 patients with 61 mid-to-proximal calculi. Twentyseven patients underwent semirigid ureterorenoscopy using the “Guidewire-Coil-Technique”, the second group (n = 28) served as control group using the guidewire as usual. There has been a statistically significant reduction of accidental stone retropulsion (2/27 vs. 8/28, p < 0.05) as well as a decreased use of auxiliary procedures (p < 0.05) compared to the control group. No difference was observed in operative time. One ureteral injury in the control group required a prolonged ureteral stenting.
The “Guidewire-Coil-Technique” is a simple and safe procedure that may help to prevent proximal calculus migration and therefore may increase stone-free rates without causing additional costs.
KeywordsStone migration Stone retropulsion Intracorporeal lithotripsy Ureterorenoscopy Ureteric calculi
During the past two decades, there have been many improvements regarding the endoscopic treatment of urolithiasis. Ureterorenoscopy (URS) with and without lithotripsy is a standard method to treat ureteral calculi depending on different factors including location, stone size, individual patient factors as well as equipping [1, 2]. A particular challenge limiting the success of ureteroscopic lithotripsy is stone retropulsion due to insertion of the ureteroscope, pressure by the irrigation fluid and/or the lithotripsy itself . Stone migration occurs in 28–60% of proximal calculi [3–6]. Hereby an increase in operative time, a decrease in stone-free rates and the need for further auxiliary procedures (i.e. shockwave lithotripsy (SWL), flexible ureterorenoscopy (fURS)) with affiliated morbidities and health-care costs have been reported [2, 7, 8]. Novel stone retrieval devices have been introduced to address the problem of accidental stone migration: Stone baskets [9, 10], suction devices , balloon catheters [12, 13] guidewire [14–16] and gel-based devices [17, 18] significantly reduced the incidence of stone retropulsion. On the contrary, these devices are associated with additional costs and some of them with a higher risk for ureteral injuries .
Because of this predicament, we assessed a new technique only using the usually recommended guidewire to prevent proximal stone migration. We here describe our experience and the efficacy of this method.
From January 2014 to December 2014, 55 patients with upper ureteral calculi (n = 61) were treated in our institution by primary intracorporeal lithotripsy according to the current guidelines . Preoperative stone location and size were confirmed by abdomen and pelvis computed tomography (CT) scan or in rare cases by intravenous pyelography (IVP), if CT scan was not available. All patients underwent semirigid ureterorenoscopy and intracorporeal lithotripsy has been performed using holmium-YAG laser (Ho:YAG) and/or pneumatic lithotriptor. The “Guidewire-Coil-Technique” in this study was performed by a single faculty urologist (S.R.) with more than 2000 ureterorenoscopies. IRB approval was obtained (no. 43/2016, Witten/Herdecke University).
All 55 patients were analyzed retrospectively: Of these patients 27 were treated using the “Guidewire-Coil-Technique” and 28 patients served as control group using the guidewire in regular fashion. Plain film radiographs of the kidneys, ureters, and bladder (KUB) and sonography were obtained to verify stone-free rate and migration rate.
Patients were stratified by the kind of use of the guidewire. The primary endpoint was the stone-free rate. The incidence of stone retropulsion, need for further auxiliary procedures, operative time and complication rate were defined as secondary endpoints. Statistical assessment was performed using Fisher’s exact test for categorical variables and Mann–Whitney U test for continuous variables respectively. P values < 0.05 were considered significant. Statistical analysis was performed using SPSS 21® for Mac® (SPSS Inc., Chicago, IL, USA).
Preoperative characteristics of both groups
n = 27
n = 28
Number of stones
Postoperative comparison of both groups
n = 27
n = 28
Operative time [min]
Stones larger than 5 mm in diameter require intracorporeal fragmentation before extraction through the ureteroscope . A wide variety of endoscopic lithotriptors have become available for stone fragmentation including laser, electrohydraulic and the pneumatic lithotriptor. The ballistic nature of the energy occasionally displaces calculi towards the kidney. Stone migration into the collecting system makes stone retrieval substantially more challenging especially into a lower pole or anterior calyx, which necessitates additional procedures such as adjuvant extracorporeal SWL [8, 21].
Overview of different devices and techniques to prevent accidental stone migration
Stone migration [%]
Kesler et al. 
Stone basket (Escape®)
Eisner et al. 
Guidewire (Stone Cone®)
Sen et al. 
Guidewire (Stone Cone®)
Sen et al. 
Wang et al. 
Sen et al. 
Gel-based (Lidocaine jelly)
Mohseni et al. 
Gel-based (Lidocaine jelly)
Rane et al. 
Thermosensitive polymer (BackStop®)
Dretler et al. 
Balloon catheter (Passport®)
The stone-free rate in the current work was different between the 2 groups (92.6% for the treatment group and 75% for the control group). The control group consequently had a higher rate of ancillary procedures as reflected by the significantly different efficiency quotient. This was partly due to stone retropulsion requiring an auxiliary procedure. In comparison to the before mentioned (expensive) stone retrieval devices and their associated stone-free rates (Table 3), our technique was not inferior.
In two patients in the group managed with the guidewire-coil-technique we were not able to prevent stone migration towards the kidney. While we did not observe any proximal stone migration during the placement of the wire there may be an association with the diameter of the dilated ureter (similar to balloon catheters) [2, 13]. Although possible in every patient in the treatment group, it took 1–8 (median 3) attempts to coil the guidewire in the renal pelvis and get a loop back into the ureter. To our experience the most important step is a direct loop in the upper calix to achieve a quick and direct turn back into the ureter. We do acknowledge that there there is a learning curve to the procedure but the steps are easily learned by the residents in our programme. Furthermore there might be anatomical conditions that make this step of the procedure challenging (e.g. a duplex collecting system).
Contrary to our expectations, we did not observe significant differences in operative time between the two groups (67.6 versus 70.3 min, P = 0.901). While multiple attempts of directing the guidewire back in the ureter can be time consuming it has been our experience that the actual procedure can be performed more efficiently and possibly faster because of a higher flow of irrigation fluid. This can result in improved vision without an increased risk of stone retropulsation.
This was not a prospective study. Patients were not randomized. By that, the retrospective character and the small number of patients are limitations of this study. Nevertheless, we were able to show the feasibility of this technique and its potential utility in the prevention of stone migration during ureteroscopy and lithotripsy.
Coiling the routinely used guidewire just proximal to the stone in the ureter prior to lithotripsy during ureteroscopy may be a simple and inexpensive option to significantly reduce inadvertent stone migration and achieve higher stone-free rates.
Institutional review board
Plain film radiographs of the kidneys, ureters, and bladder
Shock wave lithotripsy
Availability of data and materials
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.
NMD and SD have made substantial contributions to conception and design, acquisition of data as well as analysis and interpretation of data; have been involved in drafting the manuscript and have given final approval of the version to be published. FCvonR, SR and ASB made substantial contributions to conception and design as well as interpretation of data; have been involved in revising the manuscript critically for important intellectual content; have given final approval of the version to be published. Each author has participated sufficiently in the work to take public responsibility for appropriate portions of the content and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Each patient gave informed consent and the study was approved by the institutional review committee of Witten/Herdecke University (no. 43/2016).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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