Percutaneous ureteral stent placement/ or replacement
When is this exam indicated?
The positioning of the ureteral stent has generally a temporary therapeutic value upon an obstruction to the passage of urine along the ureter towards the bladder. The consequent dilatation of the upper excretory tract resulting from an obstruction to the outflow of urine can be an acute process, which usually causes a colic-like symptomatology (e.g. in case of ureteral stones) or a chronic process (e.g. in case of urothelial tumor or extrinsic compression), which usually does not cause an acute algic symptomatology. In these cases the ureteral stent maintains the patency of the ureteral lumen, so as to facilitate the passage of urine and avoid compromising renal function. It also provides immediate relief of symptoms. The ureteral stent may also be used to help in healing ureteral urinary fistulas following demolition and/or reconstructive surgery.
How is it performed?
The ureteral stent is placed retrospectively by means of a cystoscopy, which allows the identification of the ureteral ostium and the tracing of a guide wire and ureteral catheter along the ureter. Then the excretory pathway is opacified by injection of contrast medium from the catheter and the use of fluoroscopy to identify the ureteral cavities and decide where to place the distal end of the stent. At this point, the stent itself is moved up along the guide wire until it reaches the desired position. The proximal end of the stent is then released into the bladder.
The ureteral stent is maintained within the body for a time period determined by the responsible physician, based on the patient's pathology and clinical data. If the ureteral stent is to be maintained for prolonged periods, it should be replaced periodically to prevent urinary tract infections (generally every 3-4 months).
In cases of obstructing ureteral neoplasms, when drainage of the kidney is required, percutaneous nephrostomy is preferred, to avoid the risk of causing upward dissemination of the disease during stent placement. Percutaneous nephrostomy is also used in cases of complete ureteral obstruction, when stent placement might be problematic or impossible.