A ureteral stent is a long, soft tube that stretches from the kidney to the bladder. You have probably heard about cardiac stents for people who have clogged arteries. These stents hold the arteries open so blood can continue to flow to the heart. Ureteral stents are similar in that they allow the urine to drain through the ureter if there is some type of blockage.
Urologists place stents for many common types of blockages, that is, from a kidney stone, scarring, or occasionally a tumor. If the blockage is severe, it can cause the urine to back up into the kidneys. There are often no symptoms when this happens because it occurs very slowly over time.
If it happens quickly, there may be some back pain on the side that is blocked. Complete blockage will cause the effected kidney to stop working until the obstruction is relieved. Long-term obstruction can permanently damage a kidney. Finally, if both kidneys are blocked, then the patient will develop renal failure.
When ureteral obstruction is present, the first approach is usually to place a stent to bypass the obstruction. The stent is put in with the patient under anesthesia in the operating room. A cystoscope is used to place the stent.
A wire is passed through the ureteral orifice and advanced into the kidney. The stent then slides over this wire and is pushed all the way into the kidney. An X-ray machine in the operating room shows us how far up to slide the stent. The wire is then removed, leaving one end of the stent in the kidney and the other end in the bladder. The urine now has a clear path all the way down, and the kidney should quickly recover its function.
Occasionally, it is impossible to get a wire into the ureter from the bladder because of a severe obstruction or obliteration of the opening by a tumor. In these cases, the procedure will be aborted without a stent being placed, requiring an alternate type of drainage.
To relieve the obstruction, an interventional radiologist will place a nephrostomy tube into the kidney through the back. The radiologist will usually again try to place a stent, this time by passing a wire from the kidney down to the bladder with the guidance of an X-ray.
If the radiologist is able to get the wire past the obstruction, then he or she will pass a stent over the wire and leave the nephrostomy tube in place. A few days later the tube can then be removed if the stent is functioning properly.
Rarely, a stent will be unable to relieve the blockage, and an alternative such as a nephrostomy tube or surgery will need to be considered. Although stents work very well to relieve obstruction, they do have a downside. To hold the stent in place, it has a curl at each end. When the bladder is full, the curl floats away from the wall of the bladder. When the bladder is empty, however, the curl will often bump against the wall of the bladder causing irritation and spasm.
Some people will also experience an ache in the kidneys from the curl hitting the wall there. The discomfort of the stent will often improve within the first week. There are also antispasm medications that may help improve the symptoms.
Over time, any foreign material in contact with urine will tend to develop stones. To prevent this, stents need to be removed or changed within 4 to 12 months. If you have a stent, be sure to remind your urologist to schedule you for these changes.