The function of a stent is to allow urine to flow freely from the kidney to the bladder. The ureter is a narrow tube which begins in the kidney and ends in the bladder.
Many things can cause blockage to the ureter such as stones, bruising, blood clots, scar tissue and tumours. When a ureter is blocked, the kidney swells (hydronephrosis) and does not function properly. When this blockage is sudden as occurs with a renal stone, severe pain called renal colic usually follows.
A ureteric stent will relieve blockage in the ureter thereby relieving the pain and allowing the kidney to function properly.