Media Backgrounder

Endoscopic Procedures

Colonoscopy: An examination of the inside of the colon, including the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and cecum (where the small bowel attaches to the large bowel), using an endoscope - a thin, lighted flexible tube inserted through the anus. More...

Sigmoidoscopy: An examination of the inside of the rectum and sigmoid colon using an endoscope - a thin, lighted flexible tube (sigmoidoscope) inserted through the anus. Also called flexible sigmoidoscopy and proctosigmoidoscopy. More...

Endoscopy: A procedure using an endoscope to diagnose or treat a condition. There are several types of endoscopy. Those using natural body openings include esophagogastroduodenoscopy (EGD) which is often called upper endoscopy, gastroscopy, enteroscopy, endoscopic ultrasound (EUS), endoscopic retrograde cholangiopancreatography (ERCP), colonoscopy, and sigmoidoscopy. Percutaneous endoscopic gastrostomy (PEG) is a procedure that utilizes endoscopy to help placement of a tube into the stomach; a small incision in the skin is also required. Endoscopies are usually performed under sedation to assure maximal patient comfort. More...

Enteroscopy: A procedure that allows the visualization of a greater portion of the small bowel than is possible with EGD. Enteroscopy can be achieved by using a long conventional endoscope, a wireless ingestible camera (a capsule endoscopy), or a double-balloon endoscope (inserted in the mouth or through the rectum). More...

Endoscopic retrograde cholangiopancreatography (ERCP): A procedure using a specific technique to study and treat problems of the ducts involving the liver, pancreas and gallbladder. This procedure utilizes a specialized endoscope with a side-mounted camera that can facilitate passage of a catheter into the bile and pancreatic ducts. More...

Endoscopic Ultrasound (EUS): An examination with a special endoscope fitted with a small ultrasound device on the end, used to look inside the layers of the wall of the gastrointestinal tract and visualize the surrounding organs including the pancreas, liver, gallbladder, spleen and adrenal glands. The scope is inserted in the mouth or anus in the same manner as a conventional endoscope. More...

Percutaneous Endoscopic Gastrostomy (PEG): A procedure through which a flexible feeding tube is placed with the assistance of an endoscope through a small incision in the abdominal wall into the stomach. This procedure is performed in cases where oral ingestion of nourishment or medication is impossible. More...





Colonoscopy is a common, safe test to examine the lining of the large bowel. During a colonoscopy, doctors who are trained in this procedure (endoscopists) can also see part of the small intestine (small bowel) and the end of the GI tract (the rectum). This procedure is often done under sedation to assure maximal patient comfort.

During a colonoscopy, the endoscopist uses a flexible tube, about the width of your index finger, fitted with a miniature camera and light source. This device is connected to a video monitor that the doctor watches while performing the test. Various miniaturized tools can be inserted through the scope to help the doctor obtain samples (biopsies) of the colon and to perform maneuvers to diagnose or treat conditions.

Colonoscopy can detect and sometimes treat polyps, colorectal bleeding, fissures, strictures, fistulas, foreign bodies, Crohn's Disease, and colorectal cancer.

For more information see the ASGE patient education brochure Understanding Colonoscopy online at




Sigmoidoscopy, or "flexible sigmoidoscopy," lets a physician examine the lining of the rectum and a portion of the colon (large intestine) by inserting a flexible tube about the thickness of your finger into the anus and slowly advancing it into the rectum and lower part of the colon. This procedure evaluates only the lower third of the colon. Sigmoidoscopy is often done without any sedation, although sedation can be used if necessary.

Various miniaturized tools can be inserted through the scope to help the doctor obtain samples (biopsies) of the colon and to perform maneuvers to diagnose or treat conditions.

Flexible sigmoidoscopy can detect and sometimes treat polyps, rectal bleeding, fissures, strictures, fistulas, foreign bodies, colorectal cancer, and benign and malignant lesions.

Flexible sigmoidoscopy is not a substitute for total colonoscopy when it is indicated. The finding of a new, abnormally growing polyp during sigmoidoscopy, for example, is an indication for a colonoscopy to search for additional polyps or cancer. Sigmoidoscopy should not be used for polypectomy unless the entire colon is adequately prepared. This procedure should also not be used with cases of diverticulitis and peritonitis

For more information see the ASGE patient education brochure Understanding Flexible Sigmoidoscopy online at



Upper Endoscopy

Upper endoscopy allows for examination of the lining of the upper part of the gastrointestinal (GI) tract, which includes the esophagus, stomach and duodenum (first portion of the small intestine). In upper endoscopy, the physician uses a thin, flexible tube called an endoscope. The endoscope has a lens and light source, which projects images on a video monitor. This procedure is also referred to as upper GI endoscopy, or esophagogastroduodenoscopy (EGD). Upper endoscopy is often done under sedation to assure maximal patient comfort.

Upper endoscopy helps the doctor evaluate symptoms of persistent upper abdominal pain, nausea, vomiting or difficulty swallowing. It is the best test for finding the cause of bleeding from the upper GI tract and is also more accurate than X-rays for detecting inflammation, ulcers and tumors of the esophagus, stomach, and duodenum.

A physician may also use upper endoscopy to obtain small tissue samples (biopsies). A biopsy helps distinguish between benign and malignant (cancerous) tissues. Biopsies are taken for many reasons, and a doctor might order a biopsy even if cancer is not suspected. For example, a biopsy can be taken to test for Helicobacter pylori, a bacterium that can cause ulcers and celiac disease, an inflammatory condition of the small bowel that can lead to anemia, weight loss and diarrhea.

Upper endoscopy can also be used to perform a cytology (cell) test, in which a small brush is passed through the channel of the endoscope to collect cells for analysis. Other instruments can be passed through the endoscope to directly treat many abnormalities with little or no discomfort. For example, the doctor may stretch a narrow area (a stricture), detect Barrett's esophagus (a possibly precancerous alteration in the esophageal lining), detect and biopsy gastrointestinal cancers, remove polyps (usually benign growths), treat bleeding (with standard cautery or the newer argon plasma coagulation method), and detect and treat symptoms of gastroesophageal reflux disease (GERD).

For more information see the ASGE patient education brochure Understanding Upper Endoscopy online at



Enteroscopy includes several types of procedures that allow a physician to look further into the small bowel (which is up to 20 feet long) than is possible with other methods mentioned here. A physician may use a longer conventional endoscope, a double-balloon endoscope or a capsule endoscope. Enteroscopy is primarily used to find the source of intestinal bleeding, but can also be used to find lesions and determine causes for nutritional malabsorption.

An extended version of the conventional endoscope, called a "push endoscope,"may be employed to study the upper part of the small intestine down to about 40 inches beyond the stomach.  While more of the small bowel is accessible with this type of endoscopy than with EGD, it is able to visualize only a limited portion of the small bowel.  The same techniques for therapy used during EGDs are possible during push enteroscopy.

Capsule endoscopy uses a swallowable capsule containing tiny video cameras. The capsule, about the size of a large vitamin pill, contains a light source, batteries, a radio transmitter and an antenna. The capsule transmits the images to a recording device worn around the patient's waist. When complete, the recording is downloaded to a computer which displays it on a screen. The capsule is disposable and usually takes eight hours to move through the digestive system, after which it is passed harmlessly in a bowel movement. Capsule endoscopy does not require sedation and is painless. Capsule endoscopy can be used to diagnose hidden GI bleeding, Crohn's disease, celiac disease, and other malabsorption problems, tumors (benign and malignant), vascular malformations, medication injury, and to a lesser extent, esophageal disease. Currently, capsule endoscopy cannot be used to biopsy or treat any conditions. See also the media backgrounder on capsule endoscopy.

Double-balloon enteroscopy uses a basic endoscope for viewing the inside of the entire small bowel, but that endoscope travels inside another tube which is pulled along the inside of the small bowel or colon by alternately inflating and deflating two small balloons against the inside of the intestinal wall. This allows the scope to travel further, give stable images, perform biopsies, remove polyps, and perform other therapies. This procedure is done under sedation to assure patient comfort. A similar method using a single-balloon device has been recently developed. These procedures can be performed with or without the assistance of an X-ray machine (fluoroscopy). See also the media backgrounder on balloon-assisted enteroscopy.

For more information see the ASGE patient education brochure Understanding Capsule Endoscopy online at


Endoscopic Retrograde Cholangiopancreatography (ERCP)

Endoscopic retrograde cholangiopancreatography (ERCP) is a specialized technique used to study and treat problems of the liver, pancreas and, on occasion, the gallbladder. ERCP is performed under sedation. Generally, the level of sedation for ERCP is deeper than upper endoscopy and colonoscopy due to the complexity and length of the procedure.

To reach the small passageways, known as ducts, that connect these organs, an endoscope is passed through the mouth, beyond the stomach and into the small intestine (duodenum). The ducts from the liver and pancreas drain into the duodenum via a small opening known as the papilla. A thin tube (catheter) is then inserted through the endoscope into the papilla, thereby gaining access to the common bile duct and pancreatic duct that connect the liver and pancreas to the intestine. A contrast material (dye) is injected through the catheter and flows into the liver and pancreas, outlining those ducts as X-rays are taken. The X-rays can show narrowing or blockages in the ducts that may be due to a cancer, gallstones or other abnormalities. During the test, a small brush or biopsy forceps can be put through the endoscope to remove cells for study under a microscope. In addition, small cylindrical tubes (stents) can be placed within the bile duct and/or pancreatic duct to treat obstructions from either benign or malignant diseases.

ERCP can be used to diagnose biliary colic, jaundice, elevated liver enzymes, cholangitis (inflammation of a bile duct), pancreatitis (inflammation of the pancreas), and bile-duct (biliary) obstruction due to gallstones (choledocholithiasis) and cancer. ERCP can be used to treat gallstones, malignant and benign biliary strictures, cholangitis, pancreatic cancer and pancreatitis. Traditionally, ERCP was used as both a diagnostic and therapeutic endoscopic tool for evaluating diseases of the bile ducts, pancreas and gallbladder. With improved Magnetic Resonance Imaging (MRI) and the emergence of endoscopic ultrasound (EUS), ERCP is now primarily a therapeutic instrument for treating conditions of the bile ducts and pancreas.

Cholangioscopy or pancreatoscopy are adjunctive procedures performed during ERCP for selected indications, in which miniature endoscopes are passed through the conventional endoscope, to enable direct visualization of the inner lining of the bile ducts and pancreatic ducts respectively. These procedures permit the endoscopist to obtain tissue specimens directly from the inner lining of the ducts and are also used to treat stones that are difficult to remove using conventional techniques. (ASGE Technology Status Evaluation Report Gastrointestinal Endoscopy 2008; 68(3):411-421)

For more information see the ASGE patient education brochure "Understanding ERCP" online at


Endoscopic Ultrasound (EUS)

A flexible endoscope which has a small ultrasound device built into the end can be used to see the lining and wall of the esophagus, stomach, small bowel, or colon. The ultrasound component produces sound waves that create visual images of the digestive tract which extend beyond the inner surface lining and also allows visualization of adjacent organs. Endoscopic ultrasound examinations (also called endoluminal endosonography) may be performed through the mouth or through the anus. EUS is performed under sedation.

EUS provides more detailed pictures of the digestive tract anatomy. It can be used to evaluate an abnormality below the surface of the inner lining (mucosa) such as a growth that was detected at a prior endoscopy or by X-ray. EUS, because of its ability to examine the wall layers of the GI tract, provides a detailed picture of the growth, which can help the doctor determine its nature and decide on the best treatment.

EUS can also be used to diagnose diseases of the pancreas, bile duct and gallbladder when other tests are inconclusive, and it can be used to determine the stage of cancers. More importantly, EUS provides a minimally invasive method for acquiring tissue samples from gastrointestinal tumors and lymph nodes that may not be easily accessible by other methods (i.e. radiographic or surgical guidance). Fine Needle Aspiration (FNA) can be performed by passing a biopsy needle down the channel of the endoscope and across the intestinal wall under ultrasound guidance to obtain tissue for the diagnosis and staging of cancer. More recently, EUS has emerged as a therapeutic tool for treating both solid and cystic tumors of the pancreas, alleviating intractable abdominal pain secondary to advanced pancreatic cancer, and obtaining access to the bile ducts and pancreatic duct in cases of failed ERCP.

For more information see the ASGE patient education brochure Understanding EUS-Endoscopic Ultrasonography online at


Percutaneous Endoscopic Gastrostomy (PEG)

Percutaneous endoscopic gastrostomy, or PEG, is a procedure during which an endoscope assists the placement of a flexible feeding tube through the abdominal wall and into the stomach. The PEG procedure is for patients who have difficulty swallowing, problems with their appetite or an inability to take enough nutrition through the mouth. It allows nutrition, fluids, and/or medications to be put directly into the stomach, bypassing the mouth and esophagus.

In this procedure, the endoscopist uses a lighted, flexible tube called an endoscope to guide the creation of a small opening through the skin of the abdomen and directly into the stomach. This allows the doctor to place and secure a feeding tube into the stomach. Patients generally receive a sedative and local anesthesia, and an antibiotic is given by vein prior to the procedure. Patients can usually go home the day of the procedure or the next day.

A PEG does not prevent a patient from eating or drinking, but depending on the medical condition and situation, the doctor might decide to limit or completely avoid eating or drinking.

PEG tubes can last for months or years. However, because they can break down or become clogged over extended periods of time, they might need to be replaced. The doctor can remove or replace a tube without sedatives or anesthesia, although he or she might opt to use sedation and endoscopy in some cases. PEG sites close quickly once the tube is removed, so accidental dislodgment requires immediate attention.

For more information see the ASGE patient education brochure Understanding Percutaneous Endoscopic Gastrostomy (PEG) online at


Reviewed August 2014