Place ureteric stents - tubes from kidney to bladder. Remove foregin bodies - ie) if a catheter breaks off in the urinary system. Accessing the renal pelvis via needle & inserting a catheter. Malignancy: cancer of bladder,, prostate, uterine, ovaries, colon, small bowel, breast, lymphoma. Any cancer that can move from the peritoneum to omentum. Infected hydronephrosis - bacteria has collected in the static urine that isn"t draining. Post-surgical damage to ureter, ureteral fistulas & retroperitoneal fibrosis. Nephron damage & parenchymal atrophy can begin as early as few days to a week following the onset of obstruction. Elective (not an emergency, can wait 1-2 days) - with obstruction = gradual function loss. Urgent drainage - infected obstruction - septicemia = rapid renal loss. Do not want to directly puncture the pelvis (remember urine going into peritoneum) Instead, we puncture the calyces & advance the catheter through that way to the pelvis into the ureter.