Background; CTscan Hounsfield unit is considered investigation of choice in planning management of renal stones to influence surgical strategy and it defines hardness of stones so that high density stones should be excluded from ESWL.

The Objective; of this study was to evaluate the utility of the Hounsfield Unit (HU) values as a predictive factor of extracorporeal shock wave lithotripsy outcome for renal stones.

Materials and Methods; A prospective study was performed to measure stone HU values in 445 patients who underwent extracorporeal shock wave lithotripsy (ESWL) for solitary renal stones from December 2019 to January 2021. Stone size stone location, stone HU values, and stone composition were assessed. Success of ESWL was defined as: (1) being stone-free or (2) residual stone fragments <4 mm after 3 months by x-rays and ultrasound. 

Result: Total no of patients in our study included 445 cases, out of which males are 300 (67.41%) and females are 145 (32.58%).). Total no of patients in which successful ESWL with stone lysis noted in 272 (61.12%) and in 173 (38.88%) patients ESWL was not successful.

Conclusion:  In this prospective study, we found CTscan Hounsfield unit is very helpful in predicting successful outcomes of ESWL in renal calculi.

Key Words; Ctscan( computed tomography), HU (Hounsfield unit), ESWL(Extra corporeal shock wave lithotripsy).

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