1) Urolithiasis, or kidney stone disease, is a common condition caused by obstruction in the urinary tract. The most common types of stones are calcium stones, struvite (infectious) stones, and uric acid stones.
2) Hydronephrosis is dilatation of the renal pelvis and calyces caused by partial or intermittent obstruction of urine flow. It can be caused by incompetence of the pelviureteric junction sphincters or obstruction at the ureteropelvic junction.
3) Prolonged hydronephrosis leads to progressive dilation of the pelvis and calyces, thinning of the renal parenchyma