What is upper gastrointestinal endoscopy?

Endoscopy of the upper gastrointestinal tract, also referred to as oesophagogastroduodenoscopy (OGD) or gastroscopy for short, passes a thin, flexible tube fitted with a camera through the mouth to the duodenum (the initial curved segment of the small intestine). It allows the physician to examine the mucosal lining of the oesophagus, stomach and duodenum. The procedure will usually be performed by a gastroenterologist or upper gastrointestinal general surgeon, and can be done with the patient alert or under general anaesthesia.
It is an important diagnostic procedure used in the examination of diseases such as reflux oesophagitis, oesophageal varices, oesophageal cancer, gastric ulcer, gastric cancer, duodenal ulcer, and coeliac disease.
Endoscopy may be used for investigation of symptoms such as indigestion, nausea, vomiting, pain or bleeding. The physician is often able to find the source of the symptoms to guide further investigations and treatment. They can also exclude nasty diagnoses such as cancer. In addition, endoscopy has numerous therapeutic applications, particularly in the management of upper gastrointestinal bleeds, with various methods available to stop the bleeding.


What is its purpose?

Diagnostic applications
Diagnostic applications mainly focus on the inspection of possible peptic ulcers or carcinoma (cancers). Biopsies (tissue samples) can be taken during procedure by threading specialised devices through the central equipment channel of the endoscope.
Endoscopy is used to investigate symptoms such as dyspepsia (general term for upset stomach), vomiting or iron deficiency anaemia (secondary to gastrointestinal bleeding) and in patients with blood detected in their faeces. Peptic ulceration is the most common cause of gastrointestinal bleeding. Endoscopy allows examination of the entire area of the gastrointestinal tract prone to peptic ulceration and carcinoma in a single investigation.
It should be noted that the endoscope only reaches to the second part of the duodenum. Colonoscopy on the other hand, usually only reaches up to the terminal ileum (final segment of the small intestine). Thus with conventional investigation techniques, there is a segment of small intestine that is not accessible for more detailed examination.

Therapeutic applications

Endoscopy is most often used in the treatment of bleeding lesions. Ulcers, varices (abnormal, dilated tortuous veins) or other abnormalities can be treated by injecting substances that constrict vessels, occluding them with balloons or placing a small band at their base. Benign strictures (narrowings) in the stomach or oesophagus can also be opened up using endoscopic techniques. Cancers of the oesophagus, stomach and duodenum can sometimes cause obstruction, so small tubes (stents) can be placed to keep the lumen open. Laser treatment can also be used to try to kill some of the cancerous cells. Furthermore, endoscopy has been used in the treatment of gastro-oesophageal reflux disease by means of special surgery via the endoscope.


Preparing for the procedure

Before the procedure, a nurse will spend some time with you to ask and answer questions, and to make sure that there is a clear understanding of what’s going on. A doctor will also spend some time with you, going over the procedure, its benefits, risks and complications. You will then be asked to sign a consent form.
Endoscopy is often done as an out-patient procedure. You are advised not to drive to your appointment as the sedatives can take up to 24 hours to wear off.
Specific instructions will be provided by the staff at the hospital where the procedure will be performed. For 8 hours prior to the procedure, you will not be able to eat or drink anything except maybe small amounts of water until one and a half hours before the procedure. This minimises the risk of aspiration (sucking or inspiration) of gastrointestinal contents into the airways and lungs. It also ensures the upper gastrointestinal tract is empty to gain optimal views of the walls and mucosa.
Newer, thinner endoscopes are now available which reduce the need for sedation and minimise patient discomfort. Your doctor will decide whether these are suitable for your procedure.


The procedure

The nurse will insert an intravenous line, through which medications will be introduced and your vital signs (blood pressure, temperature, pulse rate and oxygen saturation) will be recorded. These will be monitored before, during and after the procedure.
When you arrive for the procedure, a local anaesthetic will be sprayed at the back of your throat to allow you to swallow the tube without gagging. Several patients also receive sedation to minimise discomfort and anxiety.
A long, flexible endoscope is passed via the mouth, through the oesophagus and stomach to reach the duodenum. Air is pumped out of the endoscope to dilate the stomach to allow better visualisation. The doctor manoeuvers the endoscope through the gastrointestinal tract. The doctor will be able to see magnified pictures of the tract on the television and thus begin to make a diagnosis.
If abnormal lesions are detected, the doctor may take a small sample (biopsy) to allow further testing, or perform procedures to stop bleeding ulcers. Specialised equipment is threaded through the tube for these purposes. The entire procedure usually takes 20-30 minutes.
After the procedure, you will stay for a few hours of observation while the sedative wears off. Your throat may feel sore and you may feel bloated. These will quickly wear off.


What are the risks?

Endoscopy is considered a relatively safe procedure and most patients will not experience anything worse than a mild sore throat. If therapeutic procedures are done the risk is slightly higher.
Possible complications are:

  • Food or fluid aspiration into the lungs
  • Tissue damage from the endoscope
  • Bleeding from biopsies and removal of polyps
  • Reactions to the sedatives and other medication
  • Irritation of the vein or sight of venous line insertion.

If the following signs are experienced, a doctor must be immediately consulted:

  • Severe abdominal pain
  • If the abdomen feels firm, distended abdomen
  • Vomiting
  • Fever
  • Difficulty swallowing or severe throat pain

References

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