A biliary stent is a metal or a plastic tube which is inserted into a bile duct to provide relief in the narrowing of the duct (also called bile duct stricture).
Purpose of ERCP + Placement of Biliary Stents
Biliary stenting is used to diagnose blockages that occur in the bile ducts. Bile is an object which helps to digest fat and it is produced by the liver, secreted through the bile ducts and is stored in the gallbladder.
Bile is released into the small intestine after a fat-containing meal has been eaten. The discharge of bile is controlled by a muscle called the sphincter of Oddi which is found at the junction of the bile ducts and the small intestine.
There are a number of conditions malignant or benign that can cause strictures of the bile duct. Pancreatic cancer is the most general malignant cause which is followed by cancer of the gallbladder, bile duct, liver, and large intestine. Non-cancerous causes of bile duct stricture include:
- injury to the bile ducts during surgery for gallbladder removal (accounting for 80% of nonmalignant strictures)
- pancreatitis (inflammation of the pancreas)
- primary sclerosing cholangitis (an inflammation of the bile ducts that may cause pain, jaundice, itching, or other symptoms)
- radiation therapy
- blunt trauma to the abdomen
Description of Biliary Stents
A biliary stent is a thin tube-like structure that is used to support a narrowed part of the bile duct and prevent the reformation of the stricture. Stents can be made of plastic or metal.
The two most normal methods which are used to place a biliary stent are Endoscopic Retrograde Cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC).
ERCP is an imaging technique which is used to diagnose diseases of the pancreas, liver, gallbladder and bile ducts that is also having the advantage of being used as a therapeutic device.
The endoscope (a thin, lighted, hollow tube attached to a viewing screen) is inserted into a patient's mouth, down the esophagus, through the stomach and into the upper part of the small intestine until the endoscope reaches the spot where the bile ducts empty.
At this point a small tube called a cannula is inserted through the endoscope and used to inject a contrast dye into the ducts the term retrograde refers to the backward direction of the dye. Then, a series of x-rays are taken as the dye moves through the ducts.
If the x-rays show that a biliary stricture exists, a stent may be placed into a duct to relieve the obstruction. In order to perform this, specific instruments are inserted into the endoscope and a sphincterotomy (a cut into the sphincter of Oddi) is performed to provide access to the bile ducts.
In some cases, the biliary stricture may first be dilated (expanded) using a thin, flexible tube called a catheter which is followed by a balloon-type device that is inflated. The stent is then inserted into the bile duct.
Diagnosis of ERCP
Prior to the ERCP, the patient will be instructed to refrain from eating or drinking for at least 6 hours to ensure that the stomach and upper part of the intestine are free of food.
The physician should be notified as to what medications the patient takes and if the patient has an allergy to iodine, which is found in the contrast dye. Antibiotics will be started prior to surgery and continued for several days afterward.