Endoscopy, gastroscopy and colonoscopy: the difference

The difference between endoscopy, gastroscopy and colonoscopy

Endoscopy, gastroscopy and colonoscopy are often confused, and that is understandable — all three are endoscopic examinations, and the terminology can sound technical. The easiest way to remember it is that endoscopy is the umbrella term for any examination where the doctor looks inside the body with a flexible camera, while gastroscopy and colonoscopy are two specific endoscopies of the upper and lower gastrointestinal tract.

The short answer

Examination	What is examined?	Where the scope enters
Endoscopy	Umbrella term for all scope examinations	Mouth, nose, anus, small skin incision
Gastroscopy	Oesophagus, stomach and duodenum	Mouth or nose
Colonoscopy	The entire colon and the junction with the small bowel	Anus
Sigmoidoscopy	Rectum and lower part of the colon	Anus

Endoscopy — the big umbrella

Endoscopy literally means "looking inside". It covers any examination where the doctor passes a flexible scope with a camera into the body. The term includes:

• Upper endoscopy (gastroscopy) of the oesophagus, stomach and duodenum
• Lower endoscopy (colonoscopy and sigmoidoscopy) of the colon
• Bronchoscopy of the airways
• Cystoscopy of the bladder
• ERCP of the bile and pancreatic ducts
• Laparoscopy (keyhole surgery) through small incisions in the abdominal wall

When a doctor says you need an endoscopy, they will usually specify which type. If a referral for the gastrointestinal tract just says "endoscopy", it usually refers to a gastroscopy or a colonoscopy.

Gastroscopy — the upper endoscopy

Gastroscopy is an endoscopic examination of the oesophagus, stomach and first part of the duodenum. It is most often done through the mouth (oral gastroscopy) with light sedation and takes 5–10 minutes. We also offer the gentler nasal version through the nose, where you can talk and breathe normally throughout the examination.

Typical reasons for gastroscopy:

• persistent heartburn or reflux
• swallowing difficulty or upper abdominal pain
• suspected peptic ulcer, Helicobacter pylori or coeliac disease
• anaemia without other explanation

Colonoscopy — the lower endoscopy

Colonoscopy is an endoscopic examination of the entire colon and the junction with the small bowel. It is done through the anus, usually with sedation and pain relief, and takes 20–30 minutes. Preparation is more involved than for gastroscopy: 3–4 days of a low-residue diet and a thorough bowel cleansing the day before.

Typical reasons for colonoscopy:

• blood in the stool or iron deficiency
• persistent change in bowel habit
• abdominal pain, bloating
• suspected inflammatory bowel disease
• screening or follow-up after polyps or bowel cancer

Sigmoidoscopy — the short colonoscopy

Sigmoidoscopy is a smaller version of colonoscopy where only the lowest 60 cm of the colon (sigmoid and rectum) is examined. It needs only an enema and no sedation, and you can drive yourself home afterwards. It is used when symptoms suggest the problem is low — for example fresh blood in the stool or suspected haemorrhoids and polyps in the lower bowel.

Which examination do I need?

The doctor decides based on your symptoms. As a rule of thumb:

• upper abdominal symptoms, heartburn, swallowing difficulty → gastroscopy
• lower abdominal symptoms, blood in the stool, change in bowel habit → colonoscopy or sigmoidoscopy
• red-flag symptoms or screening after earlier findings → often both

If you are referred for "endoscopy", call the clinic and ask which specific examination is planned, so you know how to prepare.

Read on

• Patient guide to colonoscopy
• Low-residue diet before colonoscopy, day-by-day plan
• Colonoscopy side effects and when to react
• How long a colonoscopy takes in total