The term stent appears to derive from the surname of Charles Thomas Stent (1845-1901) and is generally used to refer to tubular devices used to prevent the collapse of vessels, for example blood vessels, and other tubular structures in the body. A ureteral stent, also called a ureteric stent, is a hollow tubular device placed in the ureters for the purpose of facilitating the flow of urine from the kidney to the bladder.
They are made of metal mesh or spiral that is usually covered with a plastic material. There are different diameters to fit urethras of different sizes. The length varies between 24 and 30 cm. One end is suspended in the bladder in a hook or "J" shape to prevent it from inserting completely into the ureter and making it more difficult to remove.
What are they used for?
Urine is formed in the kidney and is channeled to the urinary bladder through the ureters, one for each kidney. In some situations it may happen that a ureter becomes blocked and prevents the passage of urinefor example, when there are kidney stones (renal stones) or prostate cancer with a tumor growth that presses on the ureters.
The blockage of urine in the kidneys manifests itself with various symptoms, such as feeling tired and loss of appetite, and can cause damage to some organs. Ureteral stents are usually placed temporarily to restore urine flow and relieve pressure on the kidneys while the cause of the blockage and its possible solution are determined. In cases of tumors and other chronic pathologies, the placement of a urethral stent can be permanent.
Ureteral stents are also used after medical procedures that irritate the ureters and can cause them to collapse. For example, ureteroscopy.
Placement and removal procedure
Ureteral stents are usually placed with the help of a cystoscope (uses fluoroscopy). The patient undergoes general anesthesia and the urologist inserts the cystoscope through the urethra and bladder until it reaches the ureter. The stent is then passed through the cystoscope and placed into the ureter. An X-ray radiograph is usually taken to verify that the stent has been placed correctly, otherwise it is removed and placed again.
Ureteral stents generally have a thread that comes out. By pulling this thread the stent can be removed in some seconds. It can be done by the patient himself, but it is advisable that it be done by an experienced nurse. It is necessary to pull with a constant force to avoid advances and stops that cause further irritation. A container should be placed under the patient to collect urine that may be expelled during the removal operation.
Threadless stents are removed using a cystoscope and must be performed by a urologist. They can also be removed using a magnetic system. The stent must have a magnet that remains free in the bladder. To remove it, a catheter with a magnet at its end is inserted into the bladder. There the two magnets are attached and the stent is simply removed. This eliminates the need for a cystoscopy which is often more painful and uncomfortable, especially in male and child patients.
Possible side effects and complications
During the time the patient has a ureteral stent in place, they may experience some side effects. Chief among these effects is increased frequency in the need to urinate usually accompanied by a sense of urgency. It is also frequent irritation, discomfort, and even pain during urinationespecially in the first days after stent insertion.
It is possible that blood appears in the urine, something that in principle would be normal due to the placement of the stent itself, although there is a risk of urinary tract infection and stone formation that stick to the device and can also cause blood to appear in the urine. To reduce adverse effects and the risk of infection, it is recommended to consume between 1.5 and 2 liters of water per day.