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Mustafa M et al, 2016: Electromagnetic and electrohydraulic shock wave lithotripsy induced urothelial damage: Is there a difference?

Mustafa M, Aburas H, Helo F, Qarawi L.
An-najah University hospitalnablus, Palestine.
An-najah National University Faculty of Medicine and Health Sciences, 455978, Nablus, Palestine.

Abstract

PURPOSE: To evaluate and compare the acute effect of electromagnetic and electrohydraulic extracorporeal shock wave lithotripsy (SWL) on the urothelial layers of kidney and ureter.
MATERIALS AND METHODS: Fifty patients (29 males (58%), 21 females (42%), with average age 51.68 years (range: 37-70) who underwent SWL application in two different centers were included. Twenty-eight patients (56%) were treated with electrohydraulic and 22 (44%) were treated with electromagnetic lithotripsy. Urinary cytological examinations were done immediately before and after SWL therapy and 10 days later. The average numbers of epithelial cells, red blood cells (RBC) and myocyte were counted under 40- magnification.
RESULTS: There were significant differences in the number of epithelial cells and RBC before and post-immediate application of SWL: 1.66 and 14.9 cell/field, (p=0.001), 5.44 and 113.45 cell/field, respectively (p=0.001). The number of RBC was significantly higher in patients treated with electromagnetic lithotripsy than those treated with electrohydraulic: 141.9 and 93.4 cell/field, respectively (p=0.02). No myocyte or basement membrane elements were detected in any of the cytological examinations. Cytological examinations done after 10 days of SWL therapy revealed recovery of all abnormal cytological findings.
CONCLUSIONS: The acute increments in the number of epithelial cells and RBC after SWL were statistically significant but it was not permanent. SWL-induced urinary urothelial lesion is limited to the mucosal layer and there was no evidence of damage to the basal membrane or muscle layer. Electromagnetic lithotripsy caused high number of RBC than electrohydraulic device on the post immediate urine cytological examination. 

J Endourol. 2016 Nov 29. [Epub ahead of print]

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Comments 1

Hans-Göran Tiselius on Monday, 03 April 2017 10:29

It is not evident to which extent this comparative study on urothelial injuries caused by EH (electrohydraulic) and EM (electromagnetic) lithotripsy contributes to a better application of this treatment modality in the clinical routine work.

Epithelial damage might be caused by direct injuries by trauma from stone fragments and/or by effects of shockwave power on the tissues.

The interpretation of the data in this article is difficult because the ratio between stones in the kidney/ureter was 1.33 in the EH-group and 3.4 in the EM-group. It is likely that one important determinant of the effects was the power density: 1.40 (90/64) MPa/mm2 for EM and 0.20 (40/201) MPa/mm2 for EH.

The most important message in this report was that in no patient were there any signs of muscle cells or fragments from the basement membrane.

The basic question raised by the authors was how shockwaves affect the contraction of the ureter, but this aspect was not part of the investigation, neither was the assumption that “adjustment of focal zone, peak pressure and shockwave frequency” was desirable in order to minimize urothelial injury with EM lithotripsy.

It is not evident to which extent this comparative study on urothelial injuries caused by EH (electrohydraulic) and EM (electromagnetic) lithotripsy contributes to a better application of this treatment modality in the clinical routine work. Epithelial damage might be caused by direct injuries by trauma from stone fragments and/or by effects of shockwave power on the tissues. The interpretation of the data in this article is difficult because the ratio between stones in the kidney/ureter was 1.33 in the EH-group and 3.4 in the EM-group. It is likely that one important determinant of the effects was the power density: 1.40 (90/64) MPa/mm2 for EM and 0.20 (40/201) MPa/mm2 for EH. The most important message in this report was that in no patient were there any signs of muscle cells or fragments from the basement membrane. The basic question raised by the authors was how shockwaves affect the contraction of the ureter, but this aspect was not part of the investigation, neither was the assumption that “adjustment of focal zone, peak pressure and shockwave frequency” was desirable in order to minimize urothelial injury with EM lithotripsy.
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