What Endoscopy Is
Endoscopy is the direct visual examination of the gastrointestinal tract using a flexible tube equipped with a camera, light source, and working channels for biopsies and therapeutic interventions. Upper GI endoscopy (OGD — oesophagogastroduodenoscopy) examines the oesophagus, stomach, and duodenum. Lower GI endoscopy (colonoscopy) examines the colon and terminal ileum.
When Endoscopy Is Needed
Endoscopy is not a first-line investigation for every gut symptom. It is indicated when alarm features are present (rectal bleeding, unexplained weight loss, iron-deficiency anaemia, dysphagia, new onset after 50), when fecal calprotectin is elevated and IBD is suspected, for colorectal cancer screening and surveillance, for investigation of persistent symptoms unresponsive to empirical treatment, and for therapeutic procedures (polyp removal, stricture dilation, variceal banding).
Preparation
For OGD: fasting for 6 to 8 hours before the procedure. No special bowel preparation. For colonoscopy: bowel preparation is required — typically a split-dose polyethylene glycol (PEG) solution or sodium picosulfate taken the evening before and morning of the procedure. Complete bowel cleansing is essential for adequate mucosal visualisation — poor preparation reduces polyp detection rates and may necessitate repeat procedures. A low-residue diet for 1 to 3 days before preparation improves cleansing quality.
Sedation Options
Conscious sedation (midazolam with or without fentanyl) is the most common approach — you are drowsy but can respond to commands. Deep sedation with propofol (administered by an anaesthetist) is used in some centres for complex or prolonged procedures. Unsedated colonoscopy is an option for motivated patients and is standard practice in some countries — it uses gas insufflation (CO₂ is preferred over air, as it is absorbed faster and causes less post-procedure discomfort) and careful technique.
During the Procedure
OGD takes approximately 5 to 10 minutes. The endoscope is passed through the mouth, down the oesophagus, into the stomach, and through to the duodenum. Biopsies (tiny tissue samples taken with forceps through the working channel) are painless. Colonoscopy takes approximately 20 to 45 minutes. The scope is inserted through the rectum and advanced to the caecum (or terminal ileum). Loops in the colon and gas insufflation can cause transient cramping. Polyps can be removed during the procedure (polypectomy), and biopsies are taken from areas of concern or randomly (to detect microscopic colitis or surveillance dysplasia).
Understanding Your Results
Endoscopy reports describe macroscopic findings (normal mucosa, ulceration, polyps, strictures, inflammation pattern). Biopsy results (histopathology) take 1 to 3 weeks and provide microscopic detail — confirming or refuting the visual impression. A macroscopically normal colonoscopy with active symptoms should prompt biopsy review — microscopic colitis, for example, can only be diagnosed histologically.
After the Procedure
Mild bloating and gas are normal as retained CO₂ is absorbed. If biopsies were taken, avoid blood-thinning medications as advised. If polyps were removed, specific aftercare instructions regarding diet, activity, and when to seek emergency care (for bleeding) will be provided. Follow-up intervals for repeat endoscopy depend on findings and are defined by evidence-based surveillance guidelines.