ARAB JOURNAL OF UROLOGY 2020, VOL. 18, NO. 4, 252–256 https://doi.org/10.1080/2090598X.2020.1805966 STONES/ENDOUROLOGY: ORIGINAL ARTICLE Prevention of stone retropulsion during ureteroscopy: Limitations in resources invites revival of old techniques Tarek K. Fathelbab, Amr M. Abdelhamid, Ahmed Z.M. Anwar, Ehab M. Galal, Mamdouh M. El-Hawy, Ahmed H. Abdelgawad and Ehab R. Tawfiek School of Medicine, Minia University, Minia, Egypt ABSTRACT ARTICLE HISTORY Received 8 April 2020 Objective: To compare a modified technique using the Dormia basket vs Stone Cone for stone Accepted 28 April 2020 entrapment to avoid proximal stone migration during ureteroscopic pneumatic lithotripsy of ureteric stones. KEYWORDS Patients and methods: Our study included all patients with ureteric stones of <15 mm who Dormia basket; pneumatic; underwent ureteroscopic pneumatic lithotripsy from January 2015 to September 2018. The lithotripsy; stone study had two arms that were conducted over two consecutive periods; the first included 72 entrapment; stone patients in whom we used the Stone Cone (Group 1) and the second included 86 patients in retropulsion whom we started to use a Dormia basket with a modification (Group 2) to guard against proximal stone migration. Results: Both groups were comparable for gender, age, and stone characteristics. Lower ureteric stones were the most prevalent as they represented 62.5% and 60.5% in groups 1 and 2, respectively; while upper ureteric stones were respectively found in 16.7% and 17.4%. Chemical stone analysis revealed that calcium oxalate stones were most predominant account- ing for 51.3% and 51.1% in groups 1 and 2, respectively. Most of the stones were radio-opaque stones representing 57% and 58.1% in groups 1 and 2, respectively. There was a significant difference in operative time, with a mean (SD) operative time was 50.9 (11.2) in Group 1 vs 58.3 (12.4) min in Group 2 (P < 0.001). The success rate, defined as no retropulsion of stone fragments, was 97.7% in Group 2 vs 91.7% in Group 1 (P < 0.01). Complications were minor and comparable between the groups. There was no difference in hospital stay between the groups, but the cost assessment favoured Group 2. Conclusion: We found that our modified-basket stone entrapment technique compared favourably with the Stone Cone to guard against stone retropulsion during ureteroscopic pneumatic lithotripsy. Our modification to the basket was found to be feasible, efficient, safe, reproducible and cost-effective in preventing proximal stone migration. This procedure is particularly suitable in cost-limited environments. Introduction To guard against this problem, many devices have been used, e.g., the Stone Cone, N-Trap, Back stop, and Ureteroscopic lithotripsy is considered the first-line Accordion. All these devices add extra cost to the treatment for ureteric stones that fail to respond to procedure [4,5]. Laser lithotripsy is associated with medical expulsive therapy (MET) or shockwave litho- the lowest incidence of stone retropulsion. Because tripsy (SWL) . Advances in ureteroscope design and of the widespread use of laser lithotripsy, retropulsion manufacture, as well as stone retrieval devices contri- prevention using additional devices has dramatically bute, to a great extent, in the reported high success rate decreased in many centres. Nevertheless, its high cost of ureteroscopic stone extraction . During uretero- has limited its use in countries with modest resources. scopic lithotripsy, the possibility of stone retropulsion Many hospitals in different parts of the developing or upward migration limits the success rate. There is world do not have sufficient resources to cover the a wide variation in the retropulsion rate depending price of a laser machine and its running costs. For this upon the kinetic energy of the lithotripter and ureteric reason, we suggest the revival of an old technique of stone level, as proximal stones have a higher rate of disassembly of a Dormia basket to prevent stone retro- stone migration than those that are distally located [1,2]. pulsion during ureteroscopic pneumatic lithotripsy. Migrating stones or fragments may necessitate additional procedures, e.g. flexible ureteroscopy, or In our centre, we used a modified-basket stone secondary procedures such as SWL, with their addi- entrapment technique to avoid proximal stone migra- tional costs; as untreated stone fragments may serve tion during ureteroscopic pneumatic lithotripsy. In this as nidi for new stone growth [2,3]. way, we could save the extra cost of anti-retropulsion CONTACT Ehab R. Tawfiek firstname.lastname@example.org Department of Urology, School of Medicine, Minia University, Minia 61111, Egypt Abbreviations: MET: medical expulsive therapy; SFR: stone-free rate; SWL: shockwave lithotripsy © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ARAB JOURNAL OF UROLOGY 253 devices and overcome the limited availability of laser Once the stone was reached in the ureter, the Stone lithotripters in centres located in areas with minimal Cone was opened above the stone and the uretero- resources. scope was re-introduced. Then pneumatic lithotripsy was performed and the fragments were extracted with a Dormia or grasping forceps. Patients and methods For Group 2, the safety guidewire was advanced under vision beside the stone, the Dormia basket (niti- Study design nol basket 3.5–4 F with four wires, Zero Tip™ nitinol This retrospective study included all patients with ure- basket, Boston Scientific) was used to catch the stone teric stones who underwent ureteroscopic stone and hold it until it was mildly entrapped. The basket removal from January 2015 to September 2018. The handle was disassembled and detached with the study had two arms that were conducted sheath, leaving the stone caught within the wires of consecutively. the basket. The ureteroscope was then re-introduced. The first arm (Group 1) was performed between Gentle support was exerted by the operator on the January 2015 and January 2016, in which we used the basket core to keep the stone entrapped within the Stone Cone® (Boston Scientific Corp, Natick, MA, USA) to basket. Pneumatic lithotripsy was used while applying avoid proximal stone migration. Because of some finan - gentle and cautious support to the basket. cial difficulties, we could no longer use the Stone Cone; Disintegration was applied to the centre of the stone therefore, we used a modification of the stone basket and continued until we could easily see the tip of between April 2016 and September 2018 (Group 2). The basket clear of stones and the basket was retrieved. present study was designed to compare the results of Re-assembling of the Dormia was done to allow for both techniques in the two consecutive periods. retrieval of any disintegrated fragments, with frag- The study comprised 208 patients who underwent ments of ≥4 mm considered significant and thus may ureteroscopic stone removal. Patients with ureteric need further procedures. stones of <15 mm treated by ureteroscopy after failure At the end of the manoeuvre, retrograde pyelogra- of MET and/or failure of SWL were included. phy was done for detection of any complications. A JJ Patients with either bilateral (n = 10), or multiple ureteric stent was left in situ for 2 weeks in all cases. (n = 24) ureteric stones and patients in whom the stone All the surgical procedures were done by two senior was extracted directly without disintegration (n = 16) expert endourologist (E.R.T. and T.KF.) were excluded from the study. There were 72 patients treated by Stone Cone (Group 1) and 86 treated by Dormia basket (Group 2). The study was approved by Postoperative evaluation our local Ethics Committee. Postoperative follow-up was done using non- enhanced multi-detector CT before the removal of Preoperative assessment the ureteric stent. Stone size and location were assessed by non- enhanced multi-detector CT. Routine laboratory tests; Statistical analysis urine analysis, culture and sensitivity were performed. The results are presented as the mean (± SD). Statistical All patients received preoperative prophylactic anti- analysis was done using the Statistical Package for the biotic. Success was defined as a safely completed pro- Social Sciences (SPSS®) for Windows, version 11.0 (SPSS cedure with no retropulsion of stone fragments, and Inc., Chicago, IL, USA). The Student’s t-test, chi-square no need for any auxiliary manoeuvres. Retropulsion test and Fisher’s exact test were used as appropriate. was considered when the stone or fragments migrated A P < 0.05 was considered statistically significant. upwards and could not be reached by ureteroscopy. Patient demographics, stone criteria, operative time, intraoperative complications, and success rates were Results reported and statistically analysed. Both groups were comparable for gender, age and stone characteristics, as shown in Table 1. Lower ure- Endoscopic procedure teric stones were the most prevalent as they repre- A semi-rigid (8–9.8 F) ureteroscope (Wolf, Knittlingen, sented 62.5% and 60.5% in groups 1 and 2, Germany) was used in all cases. Stone fragmentation respectively, with upper ureteric stones in 16.7% and was done using a pneumatic lithoclast (Swiss 17.4%, and mid-ureteric stones in 20.8% and 22.1%. LithoClast) in all cases. Chemical stone analysis revealed that calcium oxalate For Group 1, the Stone Cone was placed under stones were most predominant representing 51.3% vision via the working channel of the ureteroscope. and 51.1% in groups 1 and 2, respectively. Most of 254 T. K. FATHELBAB ET AL. Table 1. Patients’ demographics and stone data. Table 2. Overall results. Group 1 Group 2 Group 1 Group 2 Variable Stone Cone Dormia P Stone Cone (N Dormia (N Variable = 72) = 86) P Number of patients 72 86 Gender, n (%) 47 (65.2) 54 (62.8) 0.4 Operative time, min, mean 50.9 (11.2) 58.3 (12.4) 0.001* Male 25 (34.8) 32 (37.2) (SD) Female Success rate (no 66 (91.7) 84 (97.7) 0.01** Age, years, mean (SD) 37.6 (11.7) 38.1 (8.9) 0.7 retropulsion), n (%) Ureteric stone size, mm, mean (SD) 13.8 (3.5) 13.1 (4.2) 0.1 Complications, n (%) 9 (12.5) 12 (13.9) 0.5*** Stone location, n (%) 12 (16.7) 15 (17.4) Minor laceration 0 4 (4.6) Upper ureter 15 (20.8) 19 (22.1) Torn wire Middle ureter 45 (62.5) 52 (60.5) Hospital stay, h, mean (SD) 16.20 (7) 17.67 (4.51) 0.5* Lower ureter *Student’s t-test; **chi-square test; ***Fisher’s exact test. Laterality, n (%) 37 (51.3) 51 (59.3) 0.2 Right 35 (48.7) 35 (40.7) Left rate . Several manoeuvres have been described to Stone composition, n (%) 37 (51.3) 44 (51.1) 0.3 Ca-Oxalate 20 (27.8) 24 (27.9) prevent proximal stone migration, including reverse Urate 7 (9.8) 8 (9.3) Trendelenburg position and decreased irrigation pres- Mixed Stones 8 (11.1) 10 (11.7) Triple Phosphate sure and flow rate; however, these techniques, may Stone Opacity, n (%) 41 (57) 50 (58.1) 0.8 interfere with surgeon comfort and visibility [9,10]. Radio-opaque 31 (43) 36 (41.9) The use of pneumatic lithotripsy, as well as limited Radiolucent access to flexible ureteroscopes, mandate utilisation of anti-retropulsion devices to achieve higher success rates [11,12]. the stones were radio-opaque, 57% in Group1 and Many devices have been introduced to minimise 58.1% in Group 2. the incidence of proximal stone migration during ure- We recorded a significant difference in the opera- teroscopic lithotripsy including Stone Cone, entrap- tive time in favour of Group 2, at a mean (SD) of 50.9 ment net (N-Trap), Accordion, BackStop, lidocaine (11.2) vs 58.3 (12.4) min (P < 0.001). The retropulsion jelly, and thermophilic polymers [8,13]. rate was significantly different between the groups, at In the present study, we compared the Stone Cone 2.3% in Group 2 vs 8.3% in Group 1 (P < 0.01). In Group with Dormia basket stone entrapment to guard 1, retropulsion occurred in six patients (four upper and against proximal stone migration during uretero- two middle ureteric stones), and after failure of MET, scopic pneumatic lithotripsy. In 2007, Tunc et al.  SWL was performed in four and two required flexible used pneumatic lithotripsy for ureteric stone disinte- ureteroscopy. In Group 2, retropulsion occurred in two gration in 156 patients, with a reported SFR of 85.2% patients (one upper and one middle ureteric stone), and retropulsion rate of 7.1%. On the other hand, which were successfully treated by MET. Sözen et al.  used pneumatic lithotripsy in 500 Minor mucosal abrasion was recorded in 12.5% in patients and reported SFR of 95% and migration Group 1 and 13.9% in Group 2. In Group 2, we recorded rate of 2%. Neither of them used anti-retropulsion four cases in whom wires of the Dormia were inadver- devices. In the present study, we used tently torn and the Dormia was safely removed under a modification of disassembly of a Dormia basket to vision without any injury to the ureter and was prevent stone retropulsion during pneumatic litho- replaced by a new one. Hospital stay in the present tripsy. Although this technique may be practiced by study was comparable between the groups with no many urologists, nevertheless, results of its use have significant difference. For cost analysis, there was not been properly documented. A similar technique a cost saving of 240 USD per patient in Group 2, with was published by Kesler et al.  in 2008, the authors additional saving for costs of the auxiliary procedures used an Escape™ (Boston Scientific) nitinol stone required to treat the stone fragments in Group 1. retrieval basket that is a specially designed basket to A summary of overall results is given in Table 2. capture calculi and facilitate simultaneous laser litho- tripsy, resulting in a SFR of 87%. However, this device has some limitations as the stone engagement is not Discussion handled effectively in many situations, e.g. for Ureteroscopy is one of the commonest procedures for impacted stones. Also, this device is more expensive treating ureteric stones, with the stone-free rate (SFR) than the traditional nitinol wire baskets, increasing usually >95% and low morbidity . Proximal stone the cost of the procedure. migration may lead to a longer operative time, higher In the present study, the SFR was 97.7% (84/86) with incidence of residual stones and the need for auxiliary no requirement for additional procedures using the procedures, with higher morbidity and greater cost . basket stone entrapment, while the SFR was 91.7% Pneumatic lithotripters are usually associated with (66/72) when the Stone Cone was used. Nevertheless, a higher retropulsion rate, while laser has the lowest Shabana et al.  in their study using the Stone Cone ARAB JOURNAL OF UROLOGY 255 and N-Trap reported success rates of 97.1% and 95.7%, Our technique of using basket stone entrapment is respectively. safe, reproducible, easily performed, and is highly It is known that the Stone Cone specifically acts as effective for all types of stones irrespective of their a ‘backstop’ and cannot be used for stone removal. hardness with no additional cost; an issue of impor- Therefore, fragments of <3 mm may escape and this tance especially in the developing countries and for could explain the higher frequency of stone fragments those with limited resources. Limitations of our present in Group 1 of our present study. The majority of com- study include, the retrospective nature and relatively plications during ureteroscopy are minor with small sample size. Future randomised prospective stu- reported rates of 0–15.4% . Ureteric perforation dies using this technique are invited to consolidate our and avulsion are major concerns that should be present results of its clinical effectiveness and safety. avoided. In the present study, there was minor muco- sal abrasion in nine (12.5%) cases in Group 1 and 12 Conclusion (13.9%) in Group 2, with no reported major ureteric injuries, documented by retrograde pyelography per- Using a re-purposed basket stone entrapment during formed at the end of the manoeuvre. Shabana et al. ureteroscopic pneumatic lithotripsy is feasible, effi -  reported overall ureteric injuries in 9.2% of cases cient, safe, and cost-effective in preventing proximal with ureteric perforation occurring in six (1.4%). stone migration. The procedure deserves special con- Conversely, Desai et al.  observed minor mucosal sideration in cost-limited centres. abrasion in five (10%) cases, with no major complications. Author contributions There is no clear definition of clinically significant residual fragments in the related articles leading to Fathelbab TK: Project development, doing surgical proce- confusion in the reported results . dure, data collection, data analysis and manuscript writing. In a study by Desai et al. , using the Stone Cone Abdelhamid AM: Data collection. Anwar AM: Data analysis. as the anti-retropulsion device,12% of cases had resi- Galal EM: Data collection. dual fragments of >3 mm, but none required any El-Hawy MM: Data collection. additional manoeuvres; while Shabana et al.  Abdelgawad AH: Data collection. reported residual fragments in 2.9% and 4.3% of Tawfiek ER: Project development, doing surgical proce- cases in their Stone Cone and N-Trap groups, respec- dure, data collection, data analysis and manuscript writing. tively. In our present study residual fragments were observed only in two cases in Group 2 (2.3%). Disclosure statement An important issue for the stone retropulsion rate is the pressure of the irrigating fluid [10,11]. In our basket None of the contributing authors have any conflict of inter- est, including specific financial interests or relationships and entrapment technique the stone is enclosed and affiliations relevant to the subject matter or materials dis- entrapped within the Dormia basket, so we can cussed in the manuscript. increase the irrigation fluid pressure without fear of proximal escape of the stone allowing good visibility. Research involving human participants and/or Most of the recently used anti-retropulsion devices animals are safe and efficient during intracorporeal lithotripsy. Each device has its own advantages and disadvan- Consent: An informed consent was obtained from all patients tages, but the costs of each device should also be preoperatively. considered . 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Arab Journal of Urology
– Taylor & Francis
Published: Oct 1, 2020
Keywords: Dormia basket; pneumatic; lithotripsy; stone entrapment; stone retropulsion