Esophagogastroduodenoscopy

# Overview
In medicine (gastroenterology), esophagogastroduodenoscopy is a diagnostic endoscopic procedure that visualises the upper part of the gastrointestinal tract up to the duodenum. It is considered a minimally invasive procedure since it does not require an incision into one of the major body cavities and does not require any significant recovery after the procedure (unless sedation or anesthesia has been used). A sore throat is also common. 

# Alternative names
Esophagogastroduodenoscopy may be abbreviated EGD, or OGD if one uses the British spelling 'oesophago-'. It is also called upper GI endoscopy (UGIE), gastroscopy or simply endoscopy (since it is the most commonly performed type of endoscopy, the ambiguous term 'endoscopy' refers to EGD by default).

# Indications

## Diagnostic
- Unexplained anemia (usually along with a colonoscopy)
- Upper gastrointestinal bleeding as evidenced by hematemesis or melena
- Persistent dyspepsia in patients over the age of 40-45 years
- Heartburn and chronic acid reflux - this can lead to a precancerous lesion called Barrett's esophagus
- Persistent vomiting
- Dysphagia - difficulty in swallowing
- Odynophagia - painful swallowing
- Surveillance of Barrett's esophagus
- Surveillance of gastric ulcer or duodenal ulcer
- Occasionally after gastric surgery
- Abnormal barium swallow or barium meal

## Therapeutic
- Treatment (banding/sclerotherapy) of esophageal varices
- Injection of liquids through a needle (e.g. adrenalin in bleeding lesions)
- Cutting off of larger pieces of tissue with a snare device (e.g. polyps, endoscopic mucosal resection)
- Application of cautery to tissues
- Retrieval of foreign bodies that have been ingested
- Tamponade of bleeding esophageal varices with a balloon
- Application of photodynamic therapy for treatment of esophageal malignancies
- Endoscopic drainage of pancreatic pseudocyst
- Tightening the lower esophageal sphincter.

## Newer interventions
- Endoscopic trans-gastric laparoscopy
- Instillation of gastric balloons in bariatric surgery

# Equipment
- Endoscope
Non-coaxial optic fibre system to carry light to the tip of the endoscope
A chip camera at the tip of the endoscope - this has now replaced the coaxial optic fibres of older scopes that were prone to damage and consequent loss of picture quality
Irrigation channel to clean the lens
Suction/Insufflation/Working channels - these may be in the form of one or more channels
Control handle - this houses the controls
- Non-coaxial optic fibre system to carry light to the tip of the endoscope
- A chip camera at the tip of the endoscope - this has now replaced the coaxial optic fibres of older scopes that were prone to damage and consequent loss of picture quality
- Irrigation channel to clean the lens
- Suction/Insufflation/Working channels - these may be in the form of one or more channels
- Control handle - this houses the controls
- Stack
Light source
Insufflator
Suction
Electrosurgical unit
Video recorder/photo printer
- Light source
- Insufflator
- Suction
- Electrosurgical unit
- Video recorder/photo printer
- Instruments
Biopsy forceps
Snares
Injecting needles
- Biopsy forceps
- Snares
- Injecting needles

# Procedure
The patient is told not to eat for at least 4-6 hours before the procedure. Most patients tolerate the procedure with only topical anaesthesia of the oropharynx using lignocaine spray. However, some patients may need sedation and the very anxious/agitated patient may even need a general anaesthetic. Informed consent is obtained before the procedure. The main risks are bleeding and perforation. The risk is increased when a biopsy or other intervention is performed.
The patient lies on his/her left side with the head resting comfortably on a pillow. A mouth-guard is placed between the teeth, partly to protect the patient's teeth but more importantly to prevent the patient from biting on the very expensive endoscope. The endoscope is then passed over the tongue and into the orpharynx. This is the most uncomfortable stage for the patient. Quick and gentle manipulation under vision guides the endoscope into the esophagus. The endoscope is gradually advanced down the esophagus making note of any pathology. Excessive insufflation of the stomach is avoided at this stage. The endoscope is quickly passed through the stomach and through the pylorus to examine the first and second parts of the duodenum. Once this has been completed, the endoscope is withdrawn into the stomach and a more thorough examination is performed including a J-maneuver. This involves bending the tip of the scope so it resembles a 'J' shape in order to examine the fundus. Any additional procedures are performed at this stage. The air in the stomach is aspirated before removing the endoscope. Still photographs can be made during the procedure and later shown to the patient to help explain any findings.
In its most basic use, the endoscope is used to inspect the lining of the digestive tract.  Often inspection alone is sufficient, but biopsy is a very valuable adjunct to endoscopy. Small biopsies can be made with a pincer (biopsy forceps) which is passed through the scope and allows sampling of 1 to 3 mm pieces of tissue under direct vision. The intestinal mucosa heals quickly from such biopsies.
Biopsy allows the pathologist to render an opinion on later histologic examination of the biopsy tissue with light microscopy and/or immunohistochemistry. Biopsied material can also be tested on urease to identify Helicobacter pylori.

# Limitations
Problems of gastrointestinal function are usually not well diagnosed by endoscopy since motion or secretion of the gastrointestinal tract are not easily inspected by EGD.  Nonetheless, findings such as excess fluid or poor motion of gut during endoscopy can be suggestive of disorders of function.  Irritable bowel syndrome and functional dyspepsia is not diagnosed with EGD, but EGD may be helpful in excluding other diseases that mimic these common disorders.