BACKGROUND:

Urinary lithiasis is one of the most widely treated urologic diseases in Mexico. Computed tomography is the criterion standard in its diagnosis, identifying density, stone burden, size, location, and skin-to-stone distance.

OBJECTIVE:

The aims of the present study were to determine whether size, location, density, and skin-to-stone distance, as well as the patient’s body mass index, were predictive success factors following a single extracorporeal shock wave lithotripsy session and to establish the efficacy of the Richard Wolf Piezolith 3000 lithotripter.

MATERIALS AND METHODS:

A cross-sectional, analytic study was conducted on patients diagnosed with urinary lithiasis that underwent extracorporeal shock wave lithotripsy, seen at the Urology Service of the Hospital General de México within the time frame of December 2013 and June 2015. “Success” was considered when there was complete stone elimination and “failure” was the presence of any residual stone fragments. A binary logistic regression model was employed to establish the association between extracorporeal shock wave lithotripsy success and the study variables.

RESULTS:

Of the 607 extracorporeal shock wave lithotripsies performed, only 60 patients met the inclusion criteria: 30 had fragmentation and complete elimination of the stone and 30 had residual lithiasis. The binary logistic regression model showed that sex, body mass index, stone location and average size, mean skin-to-stone distance, and number of shock wave hits could not be considered success factors for extracorporeal shock wave lithotripsy. In contrast, Hounsfield units were statistically significant in relation to extracorporeal shock wave lithotripsy success (p = 0.01) (OR 6; 95% CI: 1.4-26.2).

CONCLUSIONS:

Stone density <1000 HU was a predictive success factor for extracorporeal shock wave lithotripsy. Skin-to-stone distance, body mass index, stone size, and stone location were not related to extracorporeal shock wave lithotripsy success. The overall efficacy of the Richard Wolf PiezoLith 3000 lithotripter was 50%.

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