Biliary Stenting Health Article

Definition

A biliary stent is a plastic or metal tube that is inserted into a bile duct to relieve narrowing of the duct (also called bile duct stricture).

Purpose

Biliary stenting is used to treat obstructions that occur in the bile ducts. Bile is a substance that helps to digest fats and is produced by the liver, secreted through the bile ducts, and stored in the gallbladder. It is released into the small intestine after a fat-containing meal has been eaten. The release of bile is controlled by a muscle called the sphincter of Oddi 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 common malignant cause, followed by cancers of the gallbladder, bile duct, liver, and large intestine. Noncancerous 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)
• gallstones
• radiation therapy
• blunt trauma to the abdomen

Demographics

The overall incidence of bile duct stricture is not known. Approximately 0.2–0.5% of patients undergoing gallbladder surgery or other operations affecting the bile duct develop biliary stricture.

Description

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 may be made of plastic or metal. The two most common methods that are used to place a biliary stent are endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC).

ERCP

ERCP is an imaging technique used to diagnose diseases of the pancreas, liver, gallbladder, and bile ducts that also has 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 it 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. A series of x rays are then 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 do this, special 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, followed by a balloon-type device that is inflated. The stent is then inserted into the bile duct.

PTC

PTC is similar to ERCP in that the test is used to diagnose and treat obstructions affecting the flow of bile from the liver to the gastrointestinal tract. The procedure is generally reserved for patients who have undergone unsuccessful ERCP. A thin needle is used to inject a contrast dye through the skin and into the liver or gallbladder; x rays are taken while the dye moves through the bile ducts. If a biliary stricture becomes evident, a stent may then be placed. A hollow needle is introduced into the bile duct, and a thin guide wire inserted into the needle. The wire is guided to the area of obstruction; the stent is advanced over the wire and placed in the obstructed duct.

Diagnosis/Preparation

Prior to ERCP or PTC, the patient will be instructed to refrain from eating or drinking for at least six 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.