Optimisation of shock wave lithotripsy: a systematic review of technical aspects to improve outcomes

Shock wave lithotripsy (SWL) remains an important treatment option for the management of upper urinary tract stones. The optimisation of certain technical principles can help to improve the results of SWL. We performed a systematic review based on preferred reporting items for systematic review and meta-analysis (PRISMA) standards for studies reporting on technical aspects of SWL. A literature search was conducted on the PubMed database between January 1984 and November 2018 using ‘shockwave lithotripsy’ and ‘stone’ as keywords. Summaries and manuscripts of relevant articles were reviewed in order to select studies with the best level of evidence in each theme covered during the review. From 4,135 titles, 165 abstracts and full-text articles were reviewed. Overall, SWL has good outcomes in the treatment of upper urinary tract stones. It remains the only truly non-invasive stone treatment. While stone-free rate (SFR) might not be equivalent to ureteroscopy or percutaneous nephrolithotomy outcomes, SWL can be optimised by changing several technical factors, including type of machine, patient position, number, rate and energy of shocks, stone targeting, and patient analgesia. For each of these included SWL themes, relevant and selected studies with the highest level of evidence were described and discussed. Paired with these improved technical factors and appropriate patient selection, SWL, with its low complication rates, remains an excellent treatment option in 2019.