Abstract

Abstract

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Renal haemorrhage is a severe adverse event of extracorporeal shock wave lithotripsy with an incidence of about 0.5%. This rarity had made comparative studies among lithotripter models difficult. This study examines a large number of cases and models to reveal risk factors for postoperative renal haemorrhage.

OBJECTIVE:

To assess clinical and mechanical risk factors of clinically significant renal haemorrhage after extracorporeal shock wave lithotripsy (ESWL).

PATIENTS AND METHODS:

Patient data were extracted from the Diagnosis Procedure Combination (DPC) database from 6 months per each year, 2006-2008. The availability of lithotripters in each hospital was identified. We performed logistic regression analysis, which included the generator type (electrohydraulic, electromagnetic or piezoelectric), age, gender, laterality of stones (right, left or uncertain), location of stones (kidney, ureter or uncertain), total number of treatment sessions, anaesthesia and hospital volume (HV), focal size (greater or less than 400 mm(3) ) and F2 angle (greater or less than 70°). Renal haemorrhage events were identified within the database.

RESULTS:

Overall, 81 renal haemorrhage events in 26 969 patients (32 476 ESWL sessions) at 482 hospitals with 38 lithotripter models were identified. The incidence of events was 0.50% with renal stones and 0.14% with ureter stones. Specifications of 34 lithotripter models were available. Use of piezoelectric lithotripters (vs electromagnettic, OR 0.13, P= 0.044) and high HV (≥140/year, vs ≤70/year, OR 0.49, P= 0.012) significantly decreased the risk of renal haemorrhage events. Age, gender, focal size and F2 angle did not show statistical significance.

CONCLUSION:

There is a low incidence of renal haemorrhage after ESWL. The less invasive nature of piezoelectric lithotripters and an inverse volume-outcome relationship with ESWL procedures was revealed. Age, focal size and F2 angle do not appear to have a significant impact on renal haemorrhage.

© 2012 THE AUTHORS. BJU INTERNATIONAL © 2012 BJU INTERNATIONAL

BJU Int. 2012 Oct;110(8 Pt B):E332-8. doi: 10.1111/j.1464-410X.2012.11059.x. Epub  2012 Mar 14

PMID: 22417119 [PubMed - as supplied by publisher]

Comment

Comment

Identification of risk-factors for development of renal bleeding complications associated with ESWL is hampered by the small number of patients with this complication. In this extensive analysis of almost 27,000 patients treated with an average of 1.2 ESWL sessions, only 81 cases with clinically symptomatic renal hemorrhage were found. The overall incidence of 0.3% per patient and 0.25% per ESWL-session emphasize the low risk of this complication. Nevertheless it is important to avoid this serious side-effect of ESWL for stones located in the kidney. Accordingly it would be ideal to identify specific predictive risk-factors. Unfortunately few useful conclusions in this regard can be drawn from this report. It was assumed by the authors that the lower rate of hemorrhages in high-volume centers was explained by application of a more careful treatment regimen. But although that is possible it is not shown that this really was the case.

From a physical point of view there was apparently no relationship between bleeding complications and shockwave angle or focal volume. It had been an advantage if this analysis also had included the presence or history of hypertension (as well as other previously suggested medical risk factors). Shockwave numbers and power levels used would also have been of value to see in this report.

The lesson learnt is that ESWL of stones in the kidney always should be carried out cautiously and with the risk of bleeding in mind and that this also should be the case for stones in the ureter, probably for a location close to the kidney.

Hans-Göran Tiselius