In general, a catheter is any type of hollow tube used move liquid from one place in the body to another, and is often associated with medical procedures involving the draining of fluids from different places, such as the bladder. A ureteral catheter is a type of tube that is inserted into the ureter and may be used to drain urine that is blocked in and has no other way of escaping. More often, it is used as a means of injecting contrast dye into the kidneys or ureters for an imaging procedure, and is removed once the test is completed. The ureteral catheter may also be placed into the ureter as a protective measure when the patient is undergoing a procedure involving the ureters or the immediate area.
It is not unusual for people to confuse a ureteral catheter with a urethral catheter, since they sound very much alike and both deal with the urinary tract. The main difference between the two is that the urethral catheter is used to go from outside the body into the bladder, through the urethra. This is a very common procedure and is a means of draining the bladder for people who have had or are having surgery, and for people who have medical problems that prevent them from emptying their bladders without assistance.
The ureter is a tube that does not extend to the outside of the body, but instead goes from the kidneys into the bladder. If a person has a permanent condition that involves a blocked ureter, a stent is typically used to hold the ureter open and allow the urine to pass. A stent is similar to a ureteral catheter but is designed to stay in place indefinitely; it is typically used if a person has cancer, stones, or otherwise has a blocked ureter. The stent may be placed surgically or inserted through the urethra, past the bladder and then into the ureter without the need to make an incision.
When a person is suspected of having cancer, kidney stones, or any type of blockage affecting the ureter, a ureteral catheter is used to inject the contrast dye into the area so that the walls of the kidney and ureter can clearly be seen. This is commonly performed so that computerized tomography (CT) scans or other imaging methods will be able to detect and pinpoint a blockage. Contrast material for other procedures, such as a renal flow scan or an intravenous pyelogram (IVP), may also be injected through a ureteral catheter. The catheter is normally removed during or shortly after the procedure.