EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY

Objective: To evaluate the effect of urinary calculi attenuation values fromnon enhanced computed tomography (stone radiodensity) and stone size in determiningthe outcome of treatment by ESWL. Study design: Descriptive case series study. Setting:Department of Diagnostic Radiology, Lahore General Hospital Lahore, in collaboration with theDepartment of Urology, Lahore General Hospital Lahore. Duration of study with dates: Studywas carried out over a period of six months from January 2012 to July 2012. Subjects andMethods: Seventy patients with solitary renal calculus of 05 mm – 20 mm size were evaluatedfor calculus attenuation values in Hounsfield Units on non enhanced computed tomography.Patients were being grouped according to calculus attenuation values as: 1) less than 500 HU(soft) 2) 500-1000 HU (medium) 3) more than 1000 HU (Hard). Patients were also distributed inthree groups according to stone size as: 1) 5-10 mm 2) 11-15 mm 3) 16-20 mm. Patients werebeing subsequently treated with ESWL. During each ESWL session 3000 shockwaves weregiven. Stone clearance was documented by USG within three month after start of treatment.Results: Out of 70 patients stones were cleared in 84.3% (n=59) patients. According to thestone density, the rate of stone clearance was 100% (n=19) in group 1, 88.9% (n=27) in group2 and 66.7% (n=24) in group 3. Regarding the stone size, stones were cleared in 88.9% (n=9)in group 1, 77.4% (n=31) and 90% (n=30) in group 3. The best outcome was in patients withstone diameter of 16-20 mm and a density of 1000 HU. Conclusions: The attenuation valueof stone has a greater impact on ESWL outcome than the stone size. Further these attenuationvalues of urinary tract stones before ESWL helps in determining the treatment outcome and inplanning alternative treatment in patients with likelihood of poor outcome from ESWL.