Purpose: We assess the value of non-contrast computed tomography (NCCT) as a possible predictor of renal stone disintegration by shock-wave lithotripsy (SWL), aiming for a better selection of patients.
Materials and Methods: Forty-five patients (27 males, 18 females) with a mean age of 39.1 ± 12.5 years were reviewed between August 2008 to September 2009. All patients had a solitary renal stone ranging in size from 5 to 25 mm. High-resolution NCCT was done and a bone window was used to measure stone attenuation values. SWL was performed with an electromagnetic lithotripter. Failure was defined as no stone fragmentation after 3 sessions. The impact of the patient’s sex, age, body mass index (BMI), stone location, volume, mean attenuation value, and the skin-to-stone distance on stone disintegration was statistically evaluated. The mean follow-up period was 3 months.
Results: The overall stone-free rate at 3 months was 84.4% (38 of 45 patients); 28 patients were stone free and 10 patients had residual fragments < 4 mm. The only significant predictor of residual fragments was stone density (p < 0.001). Failure of disintegration was observed in 7 patients (15.5%). Stone density > 1000 HU and BMI > 30 were the significant independent predictors of failure (p = 0.002 and 0.001, respectively).
Conclusion: Increased stone density as detected by NCCT is a significant predictor of failure to fragment renal stones by SWL. An alternate treatment should be devised for obese patients with a stone density > 1000 HU.
KEYWORDS: Stone density, shock-wave lithotripsy, non-contrast computed tomography
CORRESPONDENCE: Ehab Mohamad Galal, Urology Department, Minia University Hospital, Minia City, Egypt ( )
CITATION: UroToday Int J. 2012 October;5(5):art 44.
DOI: http://dx.doi.org/10.3834/uij.1944-5784.2012.10.03