A stent is an artificial tube made up of metal or plastic, that is inserted (temporary or permanently) into a natural tube or vessel to prevent constriction and loss of function. Stents are surgically inserted in various disease conditions including cardiac problems and non-cardiac problems.
How a stent works?
A stent is usually a metal or plastic expandable hollow tube that can be inserted via an endoscope. After insertion, a stent prevents the natural tube from collapsing. In addition, it increases the rigidity of the natural tube.
In medicine, non-cardiac stents can be divided into vascular and non-vascular. Non-vascular stents are commonly used in esophagus, duodenum, colon, bile tract, pancrease, urethra and prostate. Vascular stents are used in aortic/abdominal aneurism repair, deep vein thrombosis and in peripheral vascular disease.
What are the different types of stents?
Esophageal stents are commonly used in patients with esophageal cancer. In esophageal cancer there is narrowing of the esophageal cavity. This results in difficulty in swallowing. It can be minimized by using a stent. Even though this does not cure the cancer, it will improve patient’s quality of life. Usual esophageal stents are comparatively large and made by a metallic mesh.
Biliary stents (Bile duct stents)
Biliary stents are used to prevent or cure bile duct obstruction. Bile duct obstruction can result from cancer of a bile duct, cancer of pancrease, injury to bile ducts during surgical procedures, a condition called primary sclerosing cholangitis and gall stones. Biliary stents are usually made up of plastic.
Duodenal stents are commonly used in duodenal or gastric outlet obstruction caused by a cancer. Similar to esophageal stents, duodenal stents are used to improve the quality of life of the cancer patients.
The pancreas is the main gland responsible for digestive juice production. Diseases in the pancreas, especially diseases which cause narrowing of the main pancreatic duct, can cause tremendous suffering to the patient. The main causes are cancer, pancreatic stones and strictures due to various other problems. Pancreatic stents are used to relieve such obstruction. They are usually made of plastic.
Ureters carry urine from the kidneys to the bladder. A ureteral block due to a stone can cause kidney failure due to the backflow of urine. Ureteral stents are used as a temporary measure to improve the urine flow, until the commencement of a definitive treatment. Sometimes ureteral stents are used to improve quality of life of the cancer patients as well. It will delay a possible renal failure due to the ureteric block.
The urethra is the urine outflow tract of the bladder. In men urethra is long and passes through the prostate gland, so enlargement of the prostate gland can cause urinary retention due to urethral outflow obstruction. When prostate surgery is not suitable, doctors may decide to put a urethral or prostate stent to relieve the obstruction.
Vascular stents are used to cure an obstruction in blood vessels. This will increase the blood supply of a target organ and prevents ischemic damage. In addition vascular stents are used to treat aortic and abdominal aneurisms.
Some vascular stents are used to prevent blood clots from reaching heart. They are used in a condition called deep vein thrombosis. Here the stent acts as an umbrella to prevent blood clots from reaching the heart
Non – cardiac stents are used to prevent and treat many conditions. In addition they are used to improve the quality of life of cancer patients. However there can be many other uses of non-cardiac stents.
Oxford textbook of Surgery