Special Procedures

ERCP, also known as Endoscopic Retrograde Cholangio-Pancreatography, is an advanced endoscopic procedure designed to studies the bile duct or pancreatic duct (otherwise known as the pancreaticobiliary system) using a special side-viewing endoscope under real-time x-ray guidance. As the approach is against the natural flow of the digestive juices from these ducts, the term “retrograde” is included to distinguish it from another percutaneous antegrade approach performed by the radiologist via a needle puncture through the liver and skin. This procedure takes approximately an hour to complete and it is generally done under the care of an anesthetist for optimal comfort.

Unlike routine endoscopic procedures, ERCP is done in a prone position and requires concurrent, real-time x-ray imaging on the pancreaticobiliary system. The reason is that the furthest reachable position of the side-viewing endoscope is the descending duodenum or D2 in the proximal small bowel. Any investigation of the pancreaticobiliary system will require inserting a thin plastic tube (also known as a cannula) through a small natural opening (known as the ampulla) located at the descending duodenum (Fig2).  Since the ampulla represents the converging point of the bile duct and the pancreatic duct, both ducts can be selectively highlighted under real-time x-ray when a contrast medium is injected through the ampulla via the plastic cannula (Fig1). The radiological image obtained during ERCP serves as a route map to guide subsequent treatments, much similar to using GPS in guiding navigation.

Depending on the clinical scenario, different accessories may be used to obtain cells from the ducts or to remove stones (Fig4). To allow repeated access into the respective ducts, the ampulla opening is usually enlarged by splitting a small portion of the muscles sphincter around it using an electrocautery device (Fig3). This process also allows a smoother flow of the digestive juices without much long term side effects, since the ampulla tissue heals rapidly. At times, a plastic tube (known as a stent) may be inserted into the ducts to prevent infection. This stent ensure proper drainage for a specific duration time without any discomfort and patients are unaware of this implant in their body so long it is functioning properly. In some cases, the procedure may have to be repeated, when necessary, until the treatment is complete.

With better imaging techniques available nowadays, ERCP is reserved almost exclusively for therapeutic purposes only. Being an advanced therapeutic procedure, ERCP carries significantly higher risks than routine endoscopy. These risks include inflammation of the bile duct (cholangitis) and pancreas (pancreatitis), and bleeding and perforation of the small bowel. Some patients may also develop adverse reactions or complications related to the sedation given. As such, an overnight stay in the hospital may be required after the procedure to ensure all is well. You should discuss with your endoscopist in greater detail should your condition requires this procedure as part of the management.

Endoscopic stent placement is a minimally invasive procedure used to treat obstructions or narrowing (stenosis and strictures) in the digestive tract and bile ducts. This technique has revolutionized the management of conditions such as tumors, strictures, and other blockages that impede the normal flow of digestive fluids or food. By restoring patency to these critical pathways, stents can alleviate symptoms, improve quality of life, and even serve as a bridge to more definitive treatments. This article explores what stents are, the different types available, their functions, and how they are used to address stenosis and strictures in the digestive system.

What is a Stent?

A stent is a small, flexible tube made of either plastic or metal that is inserted into a narrowed or blocked passageway to keep it open. Stents are designed to provide structural support, allowing fluids, bile, or food to pass through the obstructed area. They are commonly used in the esophagus (Fig1), stomach, small intestine, colon (Fig2), and bile ducts. The placement of a stent is typically performed using an endoscope, a thin, flexible tube with a camera and light that allows physicians to visualize and access the digestive tract without the need for open surgery.

Types of Stents

There are two main types of stents used in the digestive tract and biliary system: plastic biliary stents and self-expanding metal stents (SEMS).

1. Plastic Biliary Stents (Fig3): These are made of polyethylene or similar materials and are often used for short-term relief of bile duct obstructions caused by conditions such as gallstones, benign strictures, or tumors. Plastic stents are relatively inexpensive and easy to insert but have a higher risk of becoming clogged over time, requiring replacement every few months.

2. Self-Expanding Metal Stents (SEMS): These stents are made of metal alloys (Fig3&4), such as nitinol (nickel-titanium), and are designed to expand once deployed. SEMS are more durable and have a larger diameter than plastic stents, making them suitable for long-term use. They are often used in cases of malignant strictures, such as those caused by pancreatic or bile duct cancers. Some SEMS are covered with a special coating to prevent tumor ingrowth, while others are uncovered to allow tissue integration.

Functions of a Stent

The primary function of a stent is to relieve obstructions and restore the normal flow of digestive fluids, bile, or food. In the digestive tract, stents can help patients with esophageal, gastric, or colorectal cancers who experience difficulty swallowing, vomiting, or bowel obstructions. In the biliary system, stents are used to treat blockages in the bile ducts, which can lead to jaundice, liver dysfunction, or severe infections.

Overcoming Stenosis and Strictures

Stenosis (narrowing) and strictures (abnormal tightening) in the digestive tract or bile ducts can result from a variety of conditions, including tumors, inflammation, scar tissue, or congenital abnormalities. These obstructions can cause severe symptoms, such as pain, difficulty swallowing, jaundice, or malnutrition. Endoscopic stent placement provides a minimally invasive solution to these problems by:

• Relieving Symptoms: By opening the blocked passageway, stents can alleviate pain, improve digestion, and restore normal function.

• Bridging to Surgery: In some cases, stents are used as a temporary measure to stabilize a patient before more definitive surgical treatment.

• Palliative Care: For patients with advanced cancers who are not candidates for surgery, stents offer a way to improve quality of life by reducing symptoms and complications.

Conclusion

Endoscopic stent placement is a vital tool in the management of digestive tract and biliary obstructions. Whether using plastic biliary stents for short-term relief or self-expanding metal stents for long-term support, this procedure provides a minimally invasive and effective solution for patients suffering from stenosis and strictures. By restoring the flow of digestive fluids and food, stents not only alleviate symptoms but also play a critical role in improving patient outcomes and quality of life. As technology advances, the development of more durable and specialized stents continues to enhance the effectiveness of this lifesaving intervention.