Chris Ho-Ming Wong et al., 2024: Risk factors of hematoma after SWL for renal calculi: analysis from RCTs and a literature review

Tuesday, 10 December 2024

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Chris Ho-Ming Wong 1, Ivan Ching-Ho Ko 1, Emmy Sui-Fan Tang 1, Steffi Kar-Kei Yuen 1, David Ka-Wai Leung 1, Angel Wing-Yan Kong 1, Peter Ka-Fung Chiu 1, Jeremy Yuen-Chun Teoh 1 2 3, Chi Fai Ng 4
1Department of Surgery, SH Ho Urology Centre, The Chinese University of Hong Kong, Clinical Sciences Building, Prince of Wales, Hospital, New Territories, Hong Kong SAR.
2Department of Urology, Medical University of Vienna, Vienna, Austria.
3Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
4Department of Surgery, SH Ho Urology Centre, The Chinese University of Hong Kong, Clinical Sciences Building, Prince of Wales, Hospital, New Territories, Hong Kong SAR.

Abstract

Objective: To identify risk factors of perinephric hematoma following extracorporeal shockwave lithotripsy (SWL) for renal calculi through combined analysis of two randomized controlled trials.

Patients and methods: This post-hoc analysis included adult patients with solitary renal calculi ranging from 5 to 15 mm, treated with SWL between 2016 and 2022. All patients received cross-sectional imaging (either non-contrast computer tomography scan or magnetic resonance imaging) two days post-SWL to assess the presence and severity of perinephric hematoma.

Results: Among 573 patients analyzed, 173 (30.9%) developed perinephric hematoma by Day 2 post-SWL. Multivariate logistic regression identified higher total energy delivered (odds ratio [OR] = 1.533, p = 0.003), higher mean stone density (OR = 2.603, p = 0.01), higher maximal stone density (OR = 3.578, p = 0.03), and lower pole stone location (OR = 1.545, p = 0.029) were risk factors for the development of hematoma. Conversely, the stepwise ramping protocol was a protective factor for hematoma formation. (OR = 0.572, p = 0.042).

Conclusions: This study elucidates key factors influencing the risk of perinephric hematoma post-SWL, highlighting the importance of procedural adjustments such as the stepwise ramping protocol to reduce complications. These insights call for targeted patient and treatment strategy optimization to enhance SWL safety and efficacy.

Int Urol Nephrol. 2024 Sep 18. doi: 10.1007/s11255-024-04205-3. Online ahead of print.
PMID: 39292362

Comments 1

Hans-Göran Tiselius on Tuesday, 10 December 2024 10:00

To avoid perinephric and/or subcapsular hematoma after SWL is one of the most important precautions with this technique.
The authors refer to a randomized controlled trial, but to which extent the study was randomized is not obvious for the reviewer. All patients were treated with a Storz Modulith SLX-F2 lithotripter, either with the standard focus 28 x 6 mm or the extended focus 50 x 9 mm.
There were 573 patients included in the study and they were treated with up to 3000 shock waves at a maximum energy level of 7, frequency 1.5 Hz. Follow-up with CT was carried out 2 days later. Thereby it is of note that 31% had perinephric hematoma. This is a level much higher than that usually reported, but generally, only patients with symptoms suggesting hematoma are subject to CT-follow-up.
The following risk factors were of importance:
High total shock wave energy (and in that regard the Storz Medical Lithotripsy index is of value)
High stone density
No stepwise ramping
Lower pole stones
Moreover, antiplatelet medication and hypertension were important.
It is suggested that the administration of low-energy shock waves in a ramping protocol is important.
It seems to be of fundamental importance to arrest anti-platelet treatment 7 days before SWL. In my own routine, that kind of medication was stopped 10-14 days before SWL, a period corresponding to the time required for new thrombocyte formation.
The importance of hypertension is emphasized and no SWL should be carried out in hypertensive patients. In my own experience it is important also to carefully treat those patients who are normotensive, but who have a history of hypertension.
In the tabulated literature review it is obvious that the frequency of hematoma varies considerably between ~1% and ~30%. With more extensive and consequent follow-up the frequency increases. Few patients with hematoma need intervention and for most patients who present with minor hematoma functional consequences are uncommon.
Bottom-line: Great care is necessary for all patients with any risk factor for hematoma.

Hans-Göran Tiselius

Hans-Göran Tiselius

To avoid perinephric and/or subcapsular hematoma after SWL is one of the most important precautions with this technique. The authors refer to a randomized controlled trial, but to which extent the study was randomized is not obvious for the reviewer. All patients were treated with a Storz Modulith SLX-F2 lithotripter, either with the standard focus 28 x 6 mm or the extended focus 50 x 9 mm. There were 573 patients included in the study and they were treated with up to 3000 shock waves at a maximum energy level of 7, frequency 1.5 Hz. Follow-up with CT was carried out 2 days later. Thereby it is of note that 31% had perinephric hematoma. This is a level much higher than that usually reported, but generally, only patients with symptoms suggesting hematoma are subject to CT-follow-up. The following risk factors were of importance: High total shock wave energy (and in that regard the Storz Medical Lithotripsy index is of value) High stone density No stepwise ramping Lower pole stones Moreover, antiplatelet medication and hypertension were important. It is suggested that the administration of low-energy shock waves in a ramping protocol is important. It seems to be of fundamental importance to arrest anti-platelet treatment 7 days before SWL. In my own routine, that kind of medication was stopped 10-14 days before SWL, a period corresponding to the time required for new thrombocyte formation. The importance of hypertension is emphasized and no SWL should be carried out in hypertensive patients. In my own experience it is important also to carefully treat those patients who are normotensive, but who have a history of hypertension. In the tabulated literature review it is obvious that the frequency of hematoma varies considerably between ~1% and ~30%. With more extensive and consequent follow-up the frequency increases. Few patients with hematoma need intervention and for most patients who present with minor hematoma functional consequences are uncommon. Bottom-line: Great care is necessary for all patients with any risk factor for hematoma. Hans-Göran Tiselius

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