Mata Alcaraz M. et al., 2023: Extracorporeal shock wave lithotripsy for lower calyx stones: predicting treatment success

Thursday, 08 February 2024

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Mata Alcaraz M, Laso García I, Mínguez Ojeda C, Artiles Medina A, Duque Ruiz G, Hevia Palacios M, Arias Fúnez F, Burgos Revilla FJ.
Servicio de Urología, Hospital Universitario Ramón y Cajal, Madrid, Spain.
Servicio de Urología, Hospital Universitario Ramón y Cajal, Madrid, Spain.

Abstract

Introduction: The use of extracorporeal shock wave lithotripsy (ESWL) for lower calyx stones is associated with a high rate of residual fragments. Our aim is to analyse the effectiveness and complications of ESWL for lower calyx stones.

Methods: Retrospective review of patients with lower renal calyx stones treated with ESWL between January-2014 and December-2020. Measurement of infundibular length, infundibular width and infundibulopelvic angle in lower renal pole to determine favourable anatomy. ESWL failure: fragments >3 mm detected in plain abdominal film, CT scan and/or renal ultrasound 3 months after treatment. Complications after ESWL, auxiliary procedures along with risk factors associated with perirenal haematoma were analysed. SPSS statistical software was used.

Results: 512 patients with lower calyx stones were treated with ESWL. 80.3% of patients had a favourable anatomy. Overall stone-free rate was 70.5%. Regarding main complications after ESWL, stainstrasse was described in 5 patients and urinary tract infection in 3 patients. 10 perirenal haematomas (2%) were reported. Statistical association was found between antiplatelet treatment and the risk of perirenal haematoma (p = 0.004). Logistic binary regression proved the association between unfavourable anatomy of the lower renal pole (p = 0.000), size of the stone (p = 0.001), number of shock waves (p = 0.003), energy applied (p = 0.038) and the need for additional treatment after ESWL.

Conclusions: ESWL can still be considered as the initial treatment option for lower renal pole stones. The size of the stone, an unfavourable anatomy of the lower renal calyx, number of shock waves and energy applied can help predict the need for additional treatment.

Actas Urol Esp (Engl Ed). 2023 Jul 11:S2173-5786(23)00089-6. doi: 10.1016/j.acuroe.2023.07.004. Online ahead of print.PMID: 37442226
English, Spanish.

Comments 1

Peter Alken on Thursday, 08 February 2024 10:00

A simple, non-sophisticated study on many patients with good results and without speculative conclusion, however, lower pole anatomy is not just lower pole anatomy.

I see three problems: patient selection, lower pole anatomy measurement and SFR determination.
Despite the large case number, a selection bias is not excluded: It is not stated how many patients were treated by URS or PNL during the same time period and if and how patients were selected for SWL.
“To determine favourable lower pole anatomy, 54 (10.5%) patients underwent intravenous urography and in 458 (89.5%) cases contrast enhanced computed tomography was performed.“ This probably inflicted high radiation dose and - if properly done - and time (1,2) which cannot be neglected if applied in a routine setting and not just for a small study
The way lower pole anatomy was measured by whom is not clearly stated.
A very recent narrative metanalysis (3) on even the lower pole angle only confirms the problem of a missing consent and standards concerning the measurements to determine the anatomy. Besides from this there is a high interobserver variation regardless of the imaging technique chosen (1-4).
Finally, there is the eternal problem of imaging to determine SFR. Simply stating “Stone-free rate (SFR) was assessed by plain abdominal film, CT scan and/or renal ultrasound 3 months after treatment.” has become standard without that the present authors can be blamed for it.

1 Rachid Filho D, et al. Kidney lower pole pelvicaliceal anatomy: comparative analysis between intravenous urogram and three-dimensional helical computed tomography. J Endourol. 2009 Dec;23(12):2035-40. doi: 10.1089/end.2009.0262.

2 Xu Y, Lyu JL. The value of three-dimensional helical computed tomography for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones. Chronic Dis Transl Med. 2016 Apr 6;2(1):42-47. doi: 10.1016/j.cdtm.2016.02.001
Free PMC article

3 Luk A, et al. Endourological Options for Small (

A simple, non-sophisticated study on many patients with good results and without speculative conclusion, however, lower pole anatomy is not just lower pole anatomy.

I see three problems: patient selection, lower pole anatomy measurement and SFR determination.  
Despite the large case number, a selection bias is not excluded: It is not stated how many patients were treated by URS or PNL during the same time period and if and how patients were selected for SWL.
“To determine favourable lower pole anatomy, 54 (10.5%) patients underwent intravenous urography and in 458 (89.5%) cases contrast enhanced computed tomography was performed.“ This probably inflicted high radiation dose and - if properly done - and time (1,2) which cannot be neglected if applied in a routine setting and not just for a small study
The way lower pole anatomy was measured by whom is not clearly stated. 
A very recent narrative metanalysis (3) on even the lower pole angle only confirms the problem of a missing consent and standards concerning the measurements to determine the anatomy. Besides from this there is a high interobserver variation regardless of the imaging technique chosen (1-4).
Finally, there is the eternal problem of imaging to determine SFR. Simply stating “Stone-free rate (SFR) was assessed by plain abdominal film, CT scan and/or renal ultrasound 3 months after treatment.” has become standard without that the present authors can be blamed for it.

1 Rachid Filho D, et al. Kidney lower pole pelvicaliceal anatomy: comparative analysis between intravenous urogram and three-dimensional helical computed tomography. J Endourol. 2009 Dec;23(12):2035-40. doi: 10.1089/end.2009.0262.

2 Xu Y, Lyu JL. The value of three-dimensional helical computed tomography for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones. Chronic Dis Transl Med. 2016 Apr 6;2(1):42-47. doi: 10.1016/j.cdtm.2016.02.001
Free PMC article

3 Luk A, et al. Endourological Options for Small (

A simple, non-sophisticated study on many patients with good results and without speculative conclusion, however, lower pole anatomy is not just lower pole anatomy. I see three problems: patient selection, lower pole anatomy measurement and SFR determination. Despite the large case number, a selection bias is not excluded: It is not stated how many patients were treated by URS or PNL during the same time period and if and how patients were selected for SWL. “To determine favourable lower pole anatomy, 54 (10.5%) patients underwent intravenous urography and in 458 (89.5%) cases contrast enhanced computed tomography was performed.“ This probably inflicted high radiation dose and - if properly done - and time (1,2) which cannot be neglected if applied in a routine setting and not just for a small study The way lower pole anatomy was measured by whom is not clearly stated. A very recent narrative metanalysis (3) on even the lower pole angle only confirms the problem of a missing consent and standards concerning the measurements to determine the anatomy. Besides from this there is a high interobserver variation regardless of the imaging technique chosen (1-4). Finally, there is the eternal problem of imaging to determine SFR. Simply stating “Stone-free rate (SFR) was assessed by plain abdominal film, CT scan and/or renal ultrasound 3 months after treatment.” has become standard without that the present authors can be blamed for it. 1 Rachid Filho D, et al. Kidney lower pole pelvicaliceal anatomy: comparative analysis between intravenous urogram and three-dimensional helical computed tomography. J Endourol. 2009 Dec;23(12):2035-40. doi: 10.1089/end.2009.0262. 2 Xu Y, Lyu JL. The value of three-dimensional helical computed tomography for the retrograde flexible ureteronephroscopy in the treatment of lower pole calyx stones. Chronic Dis Transl Med. 2016 Apr 6;2(1):42-47. doi: 10.1016/j.cdtm.2016.02.001 Free PMC article 3 Luk A, et al. Endourological Options for Small (

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