Do I need an endoscopy, colonoscopy or gastroscopy? Dr Ganesh weighs in

Many of you may have heard of the terms “endoscopy”, “colonoscopy” or “gastroscopy”, especially when we go to the doctor for a tummy ache or vomiting. But what are all these scopes and what exactly do they do for us? The terms that doctors throw around can be confusing to the layman audience, so let me help you understand them in the simplest way possible, no sweat! 

What is the difference between endoscopy, colonoscopy and gastroscopy


 An endoscopy is a procedure where your doctor uses a specialised set of tools such as an endoscope to view the inside of your body. 

An endoscope is a thin, flexible tube with an attached camera that is inserted into your body through your mouth, allowing your doctor to view the internal structure of your body. 

During an endoscopy, your doctor can then use forceps and scissors on the endoscope to operate or remove tissues for biopsies. 

In cases where I need to see your small intestine, I may order for a capsule endoscopy instead, as that area is not easily reached with a traditional endoscopy. 


A colonoscopy is a specific type of endoscopy used to detect abnormalities in the large intestine (colon) and rectum. The endoscope is inserted through the rectum to view the inside of the colon and rectum. 


A gastroscopy is another specific type of endoscopy, often referred to as the upper gastrointestinal endoscopy, where the endoscope is placed down the throat into the upper part of the gastrointestinal tract to view the oesophagus, stomach and upper part of the small intestine (duodenum). 

To avoid confusion, endoscopy is an all encompassing term used to describe the different types of scopes – the same way cryptocurrency is an umbrella term for different cryptocurrencies, such as Bitcoin, Ethereum etc. 

The type of endoscopy your doctor orders will depend on your condition and tissue samples he requires.

What is endoscopy used for? 

An endoscopy is typically used to: 

  • Help your doctor with their diagnosis, usually related to problems with the GI tract
  • Remove tissues for biopsies, known as an endoscopic biopsy.
  • Help your doctor see the inside of your body during a surgical procedure

Your doctor may order an endoscopy to help diagnose the symptoms of the following conditions: 

  • Inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease 
  • Stomach ulcers 
  • Chronic constipation 
  • Pancreatitis 
  • Gallstones 
  • Unexplained bleeding in the gastrointestinal tract 
  • Tumours 
  • Infections 
  • Blockage of the oesophagus 
  • Gastroesophageal reflux disease (GERD) 
  • Hiatal hernia 
  • Unusual vaginal bleeding 
  • Blood in urine 
  • Gastrointestinal issues 

It is likely for the doctor to obtain a medical history of your symptoms, perform a physical examination, and order some blood tests prior to an endoscopy. These tests will complement the endoscopy and help your doctor come to an accurate diagnosis of your problem. These tests may also help to determine whether an endoscopy or surgery is really needed to treat these conditions. 

What is colonoscopy used for?

A colonoscopy is typically used to: 

What is gastroscopy used for?

A gastroscopy is typically used to: 

  • Investigate intestinal signs and symptoms such as: 
Illustration of gastroscopy
  • Diagnose conditions such as 
    • Stomach ulcers 
    • Stomach cancer 
    • Oesophageal cancer 
    • Barrett’s oesophagus 
    • Coeliac disease (adverse reaction to gluten in food) 
    • Gastroesophageal reflux disease (GERD)
  • Remove tissues for biopsies
  • Treat conditions such as: 
    • Bleeding ulcers 
    • Blockages in the oesophagus 
    • Non-cancerous growths (polyps) 
    • Small cancerous tumours 

A gastroscopy used to check symptoms or confirm a diagnosis is known as a diagnostic gastroscopy. A gastroscopy used to treat a condition is known as a therapeutic gastroscopy. 

Are these scopes uncomfortable?

An endoscopy is not supposed to be painful. However, most patients may be sensitive to the camera going down the throat, so an anaesthetic throat spray and a light sedative injection will make the procedure much more comfortable. You will still be awake but drowsy so that you feel less conscious about the discomfort of the scope.


So, regardless of whether you need an “endoscopy”, “colonoscopy” or “gastroscopy”, you now know exactly what your doctor is doing, and why they are doing it. That puts you at greater ease knowing what examinations or treatments you are getting. If you want more tips on gastrointestinal know-how, head over to G & L Surgical to find out more. 


  1. Teh, J. L., Shabbir, A., Yuen, S., & So, J. B. (2020). Recent advances in diagnostic upper endoscopy. World journal of gastroenterology, 26(4), 433–447.
  2. Rastogi, A., & Wani, S. (2017). Colonoscopy. Gastrointestinal endoscopy, 85(1), 59-66.
  3. [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG) (2006) What happens during a gastroscopy? [Updated 2015 Jun 30]. Available from: 

This article was written and medically reviewed by Dr. Ganesh Ramalingam, M.D.