People often come to the clinic with a referral note that just says "scopy", and an understandable question: which one do I need? Endoscopy and colonoscopy sound similar and are both done by a gastroenterologist with a flexible camera. The difference is simple once you see it: they look at opposite ends of the digestive tract.
This article explains what each test examines, the symptoms that point to one or the other, how the preparation differs, and when it makes sense to do both on the same day.
The short answer
An endoscopy (upper GI endoscopy, also called gastroscopy or OGD) goes in through the mouth. It looks at the food pipe, the stomach and the first part of the small intestine, called the duodenum.
A colonoscopy goes in through the back passage. It looks at the whole large intestine (the colon and rectum) and often the very end of the small intestine.
So the question is really: are your symptoms coming from the top half of the gut or the bottom half?
Side by side
- Route: endoscopy through the mouth; colonoscopy through the back passage.
- What it sees: endoscopy, the oesophagus, stomach and duodenum; colonoscopy, the colon, rectum and end of the small bowel.
- Preparation: endoscopy needs 6 to 8 hours of fasting; colonoscopy needs a low-fibre diet, clear liquids and bowel-cleansing medicine.
- Time: endoscopy usually 5 to 15 minutes; colonoscopy 20 to 45 minutes.
- Sedation: optional for both. Endoscopy is often done with just a throat spray.
- Back to normal: without sedation, almost straight away; with sedation, the rest of the day off driving and work.
Symptoms that point to an endoscopy
An endoscopy test is usually advised when the problem seems to be in the upper gut. Common reasons include acidity or heartburn that keeps returning despite medicines, pain in the upper tummy, difficulty or pain while swallowing, food getting stuck, repeated vomiting, vomiting blood, black tarry stools, iron-deficiency anaemia, and weight loss without a reason. It is also used to test for H. pylori, to confirm coeliac disease with small biopsies, and to check for swollen veins (varices) in people with liver disease.
Symptoms that point to a colonoscopy
A colonoscopy test is advised when the problem seems to be lower down: fresh blood in the stool, a change in bowel habit that has lasted more than a few weeks, long-standing diarrhoea, pain in the lower tummy with warning signs, unexplained anaemia, or a family history of bowel cancer or polyps. It is also the standard test for screening and for follow-up after polyps have been removed.
When both tests are needed
Sometimes the symptoms don't point clearly in one direction. The classic example is iron-deficiency anaemia with no obvious cause: the blood could be lost anywhere along the gut. Other examples are dark stools with no clear source, or weight loss with vague abdominal symptoms. In these situations the doctor may advise both tests.
The good news is that they can usually be done on the same day, in one session, under the same sedation. The endoscopy is done first because it takes only a few minutes, and then the colonoscopy. You prepare as you would for a colonoscopy. It saves you a second visit, a second fasting day and a second dose of sedation.
Which one is more uncomfortable?
With sedation, most people feel little during either test. Without sedation, an endoscopy can cause a brief gagging feeling as the scope passes the throat, which settles quickly. A colonoscopy can cause some cramping at the bends of the colon. For many people, the least pleasant part of a colonoscopy is actually the bowel preparation the day before. You can read more in is endoscopy painful? and is colonoscopy painful?
Is either of them surgery?
No. Neither test involves a cut. Both are done through natural openings, and most people go home the same day. Biopsies and small polyp removals during the test are painless. Larger treatments done through a scope, such as removing a big polyp or an early cancer, are called advanced endoscopy and are planned separately.
How soon can I get back to normal?
After an endoscopy without sedation, most people eat and return to work within an hour or two. After either test with sedation, plan to rest for the remainder of the day and resume normal routine the next morning. A mild sore throat after an endoscopy, or bloating after a colonoscopy, usually settles within a day.
Other tests you might hear about
Sigmoidoscopy is a shorter version of colonoscopy that looks only at the last part of the colon, often for bleeding in younger people. Capsule endoscopy uses a swallowable camera pill for the small intestine, which neither endoscopy nor colonoscopy reaches fully. Endoscopic ultrasound (EUS) uses a scope with an ultrasound probe to examine the pancreas and bile ducts.
What about cost and insurance?
The cost of each test depends mainly on whether sedation is used, whether biopsies are taken and what is done to the samples. Doing both tests on the same day is usually cheaper than two separate visits. The clinic will tell you the full cost before the test. Insurance cover depends on your policy.
Do I need one even without symptoms?
For the upper gut, an endoscopy is generally not done as a routine check-up without symptoms, except in specific situations such as long-standing reflux, known Barrett's oesophagus or cirrhosis.
Colonoscopy is different. Bowel cancer often starts as a polyp that causes no symptoms for years, and removing it prevents the cancer. Many doctors therefore advise a screening colonoscopy from around 45 to 50 years of age, and earlier if a parent, brother or sister has had bowel cancer or polyps. India does not yet have a national screening programme, so this is a decision to make with your doctor based on your age and family history.
So which one do you need?
That depends on your symptoms, your age and your history, and it is exactly what a consultation is for. Dr. Shrihari Anikhindi advises only the tests you actually need, and explains why before anything is booked. Book a consultation or consult online if you would like to talk it through first.
Medically reviewed by Dr. Shrihari Anikhindi, MBBS, MD, DNB (Gastroenterology), MRCP (SCE), gastroenterologist and advanced endoscopist at Medigest Gastro, Liver & Endoscopy Clinic, Delhi. This article is general information. Please talk to your own doctor about your health.