Digestive endoscopy: exploring the digestive system

A digestive endoscopy is the primary diagnostic test for the digestive system. In the procedure, an endoscope – a flexible tube with a camera located in the tip – is passed through the interior of the digestive tract with the images recorded on a television monitor. The tube is inserted via the mouth in a gastroscopy and through the anus in a colonoscopy. The endoscope also enables tweezers to collect biopsy samples of specific tissue, and also enables the removal of polyps and other excretory lesions, both of which are completely painless.

The gastroscope has a length of approximately one meter and the colonoscope is 1.5 to 1.8 meters. There are also shorter colonoscopes, of about 60cm, called sigmoidoscopes, but these are hardly used today.

When is an endoscopy performed?

An endoscopy is indicated for the diagnosis of anomalies or problems of the digestive tract, such as tumours, malformations, haemorrhages, polyps, gastroesophageal reflux, coeliac disease, and problems with food absorption, poor digestion of food, chronic diarrhoea or suspected gastric or duodenal ulcer, among others.

In addition, an endoscopy enables minor surgical procedures inside the digestive tract, such as biopsies of tissues, extracting foreign bodies or making sutures, thus reducing the possibility of complications and avoiding the need for hospitalisation.

Preparation for gastroscopy and colonoscopy

A gastroscopy, also known as an oral panendoscopy, is performed to examine the oesophagus, stomach and upper duodenum. To be effective, the patient must fast for 8 hours prior to undergoing a gastroscopy, so the relevant part of the digestive tract is clean of food and can be seen clearly.

Before starting the gastroscopy, the vomiting reflex can be reduced with a local anaesthetic, which is usually administered as a spray of lidocaine in the throat.

A colonoscopy requires more preparation: in addition to fasting, the patient needs to eat a low waste diet in the few days prior to the colonoscopy and if necessary, some form of colonic irrigation or enema is required if the area is not sufficiently clean.

Duration of gastroscopy and colonoscopy

A gastroscopy takes of about 5 to 15 minutes to perform, but may take about 30 minutes if a biopsy or some other procedure is performed. 

A total colonoscopy is a scan of the entire colon, from the anus to the cecum or appendicular area, and sometimes it is necessary to explore the lowest portion of the small intestine called the terminal ileum. In this case, a colonoscopy can last from 15 to 60 minutes depending on the characteristics of the colon and the experience of the specialist who performs the scan.

Are gastroscopy and colonoscopy painful?

A gastroscopy can be uncomfortable but generally does not cause the patient any pain. The local anaesthesia in the throat is usually enough to make it quite bearable. The biggest issue is the vomit reflex caused by the passage of the endoscope. As the path followed is the same as for food, the airway is free and the patient can breathe freely through the nose, mouth or both.

A total colonoscopy, unlike a gastroscopy, is an annoying and painful examination because of the insufflation of air and the friction of the endoscope. For this reason, in recent years most colonoscopies are performed under sedation or general anaesthesia.

Currently, endoscopies are generally performed when the patient is sedated unless specified by the doctor or requested by the patient. 

Risks of gastroscopy or colonoscopy

Both gastroscopy and colonoscopy are very safe examinations in the hands of good specialists, and there is only a risk of complications (usually perforations) in very exceptional cases with inexperienced professionals who are not used to performing endoscopies.

There are no curative actions to undertake after an examination except for those stipulated for when the patient was sedated or in the case of any therapeutic requirement for individual patients. 

After treatment, endoscopes follow an intense process of cleaning and sterilisation in order to avoid the transmission of diseases.