Patient Information
Tests and Treatments: Interventional Tests: Endoscopies: Introduction
Endoscopy is an important tool for gastroenterologists and other specialists dealing with problems of the digestive tract. Endoscopes are thin, flexible telescopes that allow trained specialists to examine most areas of the gut. At the end of the endoscope is a tiny video camera, which allows the doctor to see the lining of the gut up close and in color on a video monitor.
Examinations of different parts of the gut have different names.
- Upper endoscopy (or esophagogastroduodenoscopy – EGD) refers to examination of the esophagus (swallowing passage, gullet), stomach and upper part of the small intestine (duodenum). The endoscope is passed gently through the mouth.
- Sigmoidoscopy and colonoscopy refer to endoscopy examinations of the large bowel, through the anus. The sigmoidoscopy procedure examines only the distal one or two feet of the large bowel (anus, rectum and sigmoid colon), whereas colonoscopy refers to examination of the entire large bowel (colon), when necessary.
- ERCP (endoscopic retrograde cholangiopancreatography) is an extension of upper endoscopy, which allows specialists to probe the ductal (drainage) systems of the liver, bile ducts and pancreas. After finding the common drainage hole for these ductal systems (the papilla of Vater), the doctor injects dye, and x-ray pictures are taken.
- Enteroscopy refers to endoscopic examination of the small intestine beyond the upper part (duodenum). Since the small intestine is long and tortuous, longer instruments and special techniques are necessary.
All of these endoscopy examinations have many things in common. The instruments are marvels of engineering, and thus rather expensive. Special controls allow doctors to move the tip of the instruments (with steering wheels or Nintendo-like joy sticks), to blow air into the gut and suck fluids and waste residues out to clear the view. Endoscopes have an inner channel through which doctors can pass other devices for special methods of diagnosis and treatment.
Diagnostic Devices
Many diagnoses can be made simply by looking at the video images, and at recordings taken on DVD or prints. However, it is often helpful to take small specimens of tissue from the lining of the gut for detailed analysis in the laboratory. By this means it is possible to detect the presence and type of any infection or inflammation, and to look for cancerous cells. These specimens are taken with small biopsy forceps. You do not feel these probings. Smaller tissue samples can be obtained for cytology examination, using a small brush device.
Treatment Methods
Endoscopic treatments have revolutionized the management of many digestive diseases over the last 20 years. Many conditions which used to require major surgery can now be treated by endoscopy on an outpatient basis.
Narrowings of the gut can be stretched using dilating devices or balloons. These are used particularly for narrowings (strictures) of the esophagus and stomach outlet, and in some strictures of the colon. When narrowings in and around the gut cannot be relieved completely by stretching and cutting, it is sometimes necessary to leave a splinting device (stent) behind, to keep the area open. Stents are plastic tubes, or devices made of a metal mesh which expands once they have been placed correctly.
Certain diseases of the gut can cause serious bleeding. Varices are large blood vessels which bulge into the esophagus and stomach. These are treated through the endoscope by injection sclerotherapy or banding. Likewise, ulcers of the stomach and duodenum can bleed. These are treated at endoscopy by injecting medicines into the base of the ulcer, where the blood vessel is leaking, and then by cauterizing the vessel with the tip of a special catheter.
Polyps are small wartlike tumors that arise from the gut wall, most commonly found in the colon. Since some can turn into cancer, they must be removed. This is done using the colonoscope, and a small wire snare (or lasso). Electrical current is applied to cut off the polyp cleanly with some cauterization, to prevent bleeding.
Stones in the bile duct and pancreas (and other types of obstruction) can be treated during the ERCP procedure, using various cutting and grasping devices.
Percutaneous endoscopic gastrostomy (PEG) is a method used to help feeding in patients with major problems of swallowing. A small tube is placed through the skin and into the stomach, under endoscopic control.
Discomforts and Risks
The simplest endoscopic examinations (i.e. sigmoidoscopy) are usually performed without any sedation. However, most people find more complicated procedures somewhat uncomfortable quite apart from natural anxiety. Thus, it is usual to give conscious sedation. This means an injection into the vein of medicines (usually a combination) which produce relaxation and twilight sleep. There are usually few if any recollections of the procedure. Patients wake up within an hour, but the effects of the medicines are more prolonged, so it is not safe to drive until the next day. General anesthesia is given in only very special circumstances (in young children, and when very complex procedures are planned).
Obviously, the gut needs to be empty for doctors to get a good view. Thus, for upper endoscopy and ERCP, it is recommended to have nothing by mouth for at least six hours (usually overnight). For colonoscopy examinations it is necessary to take special laxative preparations to empty the bowel of residue.
Performing these endoscopic procedures safely and successfully requires special training. This is an intregal part of being a gastroenterology specialist (gastroenterologist) nowadays. Other specialists such as abdominal surgeons also receive appropriate training in some or all of these procedures. Doctors are assisted by specially trained nurses and technicians. Their job is to look after the patient's safety during the procedure, and to provide the specialist with all of the necessary equipment, properly prepared. Endoscopic doctors and nurses belong to specialist organizations in many countries. These organizations can provide detailed information about appropriate use of these techniques.
Risks of Endoscopy
Endoscopy has become very popular throughout the world because it provides good diagnoses, and allows many treatments which previously required abdominal surgery. However, no medical technique is completely safe. Endoscopy has potential complications. Specialists and their assistants do everything in their power to prevent these complications, but you should understand what can happen. Details are given where the individual procedures are described in more detail. There are two types of complication – general and specific. The general complications are those which can occur (rarely) during any type of endoscopic procedure. Thus, there may be a reaction to the sedation medicines, or the stress of the procedure may have an adverse effect on an existing illness (i.e. heart or lung disease). Very rarely the tip of the endoscope may go through a weakened part of the gut wall. This is called a perforation, and almost always requires surgical operation. Some complications relate only to special types of endoscopy. Thus, any endoscopic treatment that includes cutting (for example, removal of polyps or stones) can result in bleeding – which can usually be controlled through the endoscope. ERCP manipulation of the pancreas can cause pancreatitis.
Some complications are relatively mild (i.e. a sore vein for a week or two where the medicine has been injected). Others such as bleeding and perforation can be quite serious, resulting in long periods in hospital and operations. The chance of dying after an endoscopic procedure depends on the circumstances. For the simple procedures (i.e. upper endoscopy and sigmoidoscopy), in a healthy patient, the risk is vanishingly small – probably one in 5,000 procedures. When endoscopy is being done to treat a life threatening condition in a patient who is severely ill, the risk of a fatal outcome may be 1 or 2%.
Because of all these variations, it is not possible to generalize about the risks of endoscopy, so it is necessary to discuss these individually with your specialist.