Alsmadi JK., 2022: Shock Wave Lithotripsy Outcomes for Upper and Lower Ureteral Stones in Non-obese and Non-Pre-stented Adults: Is One Session Sufficient?
Department of General Surgery and Anesthesia, The Hashemite University, Faculty of Medicine, Zarqa, JOR.
Purpose This study aims to evaluate differences in shock wave lithotripsy (SWL) outcomes between upper and lower ureteral stones and identify patients who are likely to have a stone-free status after one session of SWL. Materials and methods After approval from the institutional review board and from a prospectively maintained database of 628 patients, 182 were retrospectively identified, who have had SWL for a single lower or upper ureteral stone and met the inclusion criteria. Age, body mass index (BMI), and stone size were similar among the groups. This study included non-pre-stented patients with solitary lower or upper ureteral radiopaque stones identified on non-contrast-enhanced computed tomography (NCCT), did not have acute obstruction, and had either normal body mass index (BMI) or overweight status. Patients were treated with Sonolith i-sys electroconductive lithotripter (focal length: 21 cm) (EDAP TMS, Vaulx-en-Velin, France). Success was defined as the absence of residual of any size or a residual of ≤2 mm on NCCT after one month, whereas failure was having fragments >2 mm or requiring surgical intervention. Post-SWL assessments were completed one week after every session with an X-ray of the kidney-ureter-bladder (KUB-XR) and NCCT after one month. Results The upper and lower ureteral stone-free rates (SFRs) were 95% and 64.7%, respectively. Of them, 65% and 45%, respectively, were stone-free after one session. The cohort having a stone-free status after one SWL session was similar in age, sex, BMI, and stone density. The upper ureteral stone arm has a significant chance for one SFR session with a larger stone size, shocks per session, and maximum power delivered. In the receiver operating characteristic (ROC) curves, the optimal cut point number of sessions of 1.5, mean stone density (MSD) of 895, and stone size of 10.5 mm are the most likely to have successful SWL in the ureter. Conclusion For patients having ureteral stones with favorable factors, SWL modality is effective and safe. Moreover, SWL can be done for one or two sessions only with the presence of favorable factors.
Cureus. 2022 Sep 26;14(9):e29592. doi: 10.7759/cureus.29592. eCollection 2022 Sep. PMID: 36176477. FREE ARTICLE
This is a good open access paper with useful messages on proper patient selection to increase the success rate of ESWL. It is a rather unusual single author publication in the Cureus journal. The author is obviously devoted to his research. A look at PubMed shows that he has travelled as far as China to collaborate and publish (1, 2) with G. Zeng, an experienced stone man. It is a good quality author driven publication (ADP) (see the review of 3).
It is an old story that stones of the lower ureter are less responsive to ESWL than stones of the upper ureter: 61.5% vs 82,9 % in 2003 (4) similar to 64,7% and 95% in the present study. However, this is just a fuzzy description and summary of the treatment. In the present study, stone size and mean stone density (HU) in the two groups were not significantly different. So in vivo, one could not tell a difference between an upper and a lower ureteric stone. A look at those stones successfully treated with one session shows the essential differences:
Despite the bigger size, the upper stones responded better because more power was applied. It is not the stone but the treatment conditions that influence the success. Their proper description would give more information on the treatment than the anatomical stone location. Supine patient position - upper stones - and prone position - lower stones - offer different conditions for the shock wave application and the way the stones are hit and these are governing the results. E.g. depending on the position of the stone in the curved track of the ureter in the lesser pelvis shock waves may hit the stone perpendicular or from the top and the gas containing intestine hinders their propagation.
Especially in regard of the latter condition, it would be interesting to know how effectively the localization system has been used. “For ultrasonically visible ureteral stones, the ultrasound probe was connected to the machine with Visio-Track technology for continuous real-time tracking and treatment monitoring of the stone. In a previous study the advantage of “continuous target monitoring” translated into a superior treatment efficacy rate of 79,5% compared to 54,5% under standard conditions in treating renal stones (5). However, sonography is impossible through gas-containing intestine. Like this the conditions of treating upper or lower ureteric stones vary significantly.
1 Huang J, Zhao Z, AlSmadi JK, Liang X, Zhong F, Zeng T, Wu W, Deng T, Lai Y, Liu L, Zeng G, Wu W. Use of the ureteral access sheath during ureteroscopy: A systematic review and meta-analysis. PLoS One. 2018 Feb 28;13(2):e0193600. doi: 10.1371/journal.pone.0193600. PMID: 29489912; PMCID: PMC5831629.
2 AlSmadi JK, Li X, Zeng G. Use of a modified ureteral access sheath in semi-rigid ureteroscopy to treat large upper ureteral stones is associated with high stone free rates. Asian J Urol. 2019 Jul;6(3):217-221. doi: 10.1016/j.ajur.2018.12.008. Epub 2019 Jan 7. PMID: 31297312; PMCID: PMC6595155.
3Alić J, et al. The Efficiency of Extracorporeal Shock Wave Lithotripsy (ESWL) in the Treatment of Distal Ureteral Stones: An Unjustly Forgotten Option? Cureus. 2022 Sep 1;14(9):e28671. doi: 10.7759/cureus.28671. eCollection 2022).
4 Delakas D, et al. Independent predictors of failure of shockwave lithotripsy for ureteral stones employing a second-generation lithotripter. J Endourol. 2003 May;17(4):201-5. doi: 10.1089/089277903765444302.
5 Abid N, Ravier E, Promeyrat X, Codas R, Fehri HF, Crouzet S, Martin X. Decreased Radiation Exposure and Increased Efficacy in Extracorporeal Lithotripsy Using a New Ultrasound Stone Locking System. J Endourol. 2015 Nov;29(11):1263-9. doi: 10.1089/end.2015.0175. Epub 2015 Aug 21. PMID: 26133199; PMCID: PMC4649770.