If your doctor has recommended a gastroscopy or colonoscopy, it’s normal to feel anxious — especially if you’ve never had an endoscopy before. The good news is these procedures are very common, usually straightforward, and can provide vital information (and sometimes treatment) without surgery.
What’s the difference?
Gastroscopy (also called an upper endoscopy) uses a thin flexible camera to examine the oesophagus, stomach and first part of the small intestine.
Colonoscopy examines the large bowel (colon) and the end of the small bowel.
Both procedures help doctors investigate symptoms, rule out serious conditions, and guide the best treatment.
Why might I need a gastroscopy?
A gastroscopy is often recommended if you have:
- Trouble swallowing or food feeling “stuck”
- Ongoing reflux/heartburn despite treatment
- Upper abdominal pain or persistent nausea
- Unexplained iron deficiency (low iron)
- Vomiting blood or black stools (urgent)
- A need to check for conditions such as ulcers, inflammation, coeliac disease, or Barrett’s oesophagus
Importantly, many stomach and oesophageal problems can look similar based on symptoms alone — a gastroscopy can provide clarity.
Why might I need a colonoscopy?
A colonoscopy is commonly recommended for:
- Blood in the stool or positive bowel screening tests
- Change in bowel habit (especially persistent diarrhoea or new constipation)
- Unexplained weight loss or anaemia
- Persistent abdominal pain
- Assessment and monitoring of inflammatory bowel disease
- Family history that increases bowel cancer risk
A key advantage is that polyps can often be removed during the procedure, which can reduce the risk of bowel cancer developing later.
What actually happens on the day?
These procedures are performed under sedation, meaning you won't feel any pain or discomfort, and you won't remember much (usually, you won't be aware at all). You’ll be monitored closely throughout. A gastroscopy typically takes 5–15 minutes, and a colonoscopy often takes 20–40 minutes, depending on what needs to be done.
Afterwards, you’ll rest in recovery until you’re ready to go home — generally, you’ll need someone to take you home.
What about the risks?
Serious complications are uncommon, but can include bleeding (especially if a polyp is removed) or, very rarely, a tear in the bowel wall. Your specialist will discuss your individual risks and benefits beforehand. For most people, the benefit of accurate diagnosis and early detection outweighs the risks.
The hardest part is often the preparation
For colonoscopy, the bowel prep is often the most challenging step — but it’s also crucial. A clean bowel means a safer procedure and a more accurate result. Your team will give clear instructions, and we can tailor prep options where appropriate.
When should I seek urgent help?
If you have vomiting blood, black stools, significant bleeding, severe abdominal pain, fainting, or rapid weight loss, seek urgent medical care.
Reassurance
Most endoscopies are done to rule out serious disease and help you feel better with the right plan. If you’re unsure whether you need the test, ask your doctor or specialist to explain the specific reason in your case — understanding the “why” can make the process much less stressful.