Harder renal stone having less satisfactory results with ECWL is -

Ans is 'd' i.e., Cystine stone Extracorporeal Shockwave Lithotripsy (ECWL):* A urinary calculus has a crystalline structure. Bombarded with shock waves of sufficient energy it disintegrates into fragments.* The clearance of stone from the kidney using ESWL will depend upon the consistency of the stone and its site.* Most oxalate and phosphate stones fragment well and, if lying in the renal pelvis, will clear within days.* The results with harder stones, especially cystine stones, are less satisfactory.* When treating calyceal stones, the patients should be warned that the clearance of fragments may take months.* The principal complication of ESWL is infection. Many calculi contain bacteria, which are released from the broken stone. It is wise to give prophylactic antibiotics before ESWL, and an obstructed system should be decompressed by the insertion of a ureteric stent or percutaneous nephrostomy before treatment.