Key Takeaways
- Gastroscopy examines the oesophagus, stomach and duodenum via an endoscope passed through the mouth.
- Colonoscopy examines the colon and rectum via an endoscope passed through the rectum.
- Gastroscopy investigates symptoms like heartburn or swallowing difficulty; colonoscopy investigates rectal bleeding, altered bowel habit or chronic constipation.
- Colonoscopy allows both detection and removal of polyps in one procedure, and is used for routine colorectal cancer screening from around age 50.
- Both are usually outpatient day cases performed under sedation.
Gastroscopy and colonoscopy are both common endoscopy procedures, and patients are often unsure which one they need — or why a doctor might recommend one over the other. Both use a thin, flexible camera to examine the inside of the digestive tract, but they look at completely different areas and are used to investigate different symptoms.
What Is a Gastroscopy?
A gastroscopy examines the upper gastrointestinal tract — the oesophagus, stomach and duodenum. A thin, flexible endoscope with a tiny camera is passed through the mouth and down towards the stomach, transmitting images to a monitor in real time. It's typically used to investigate symptoms such as recurring indigestion or heartburn, upper abdominal pain, difficulty swallowing, or repeated vomiting.
What Is a Colonoscopy?
A colonoscopy examines the opposite end of the digestive tract — the entire lining of the colon and rectum. A long, flexible colonoscope is inserted into the rectum and advanced through the colon, allowing the doctor to inspect the bowel lining, take biopsies, and remove polyps where needed. It's often described as the gold-standard test for colorectal conditions, since it allows both detection and treatment in a single procedure.
Key Differences Between the Two Procedures
- What's examined — gastroscopy looks at the oesophagus, stomach and duodenum; colonoscopy looks at the colon and rectum
- How the endoscope is introduced — gastroscopy via the mouth; colonoscopy via the rectum
- Preparation required — gastroscopy generally requires fasting beforehand; colonoscopy requires a more thorough bowel preparation in the day or two prior
- Typical duration — a gastroscopy is usually quicker, often around 10 minutes, while a colonoscopy typically takes under an hour
Common Reasons These Procedures Are Performed
Gastroscopy is commonly used to investigate persistent heartburn, suspected ulcers, or difficulty swallowing. Colonoscopy is commonly recommended for rectal bleeding, a change in bowel habit, a family history of colon or rectal cancer or polyps, unexplained anaemia, or chronic constipation that needs further investigation. Both procedures can also be used for routine screening in the absence of symptoms.
Preparing for Your Procedure
Before a gastroscopy, you'll generally be asked to avoid eating or drinking for several hours beforehand. Before a colonoscopy, a bowel preparation (a cleansing regimen taken over one to two days) is required so the bowel lining can be seen clearly. Exact instructions vary from patient to patient and will be explained in full ahead of your procedure.
What to Expect on the Day
Both procedures are typically performed as outpatient day cases under sedation, with a competent anaesthetist involved, so most patients feel little to no discomfort. Afterwards, you'll rest briefly before being discharged. Because sedation is used, you'll need someone to drive you home, and for a colonoscopy in particular, it's advisable to have someone with you for the following several hours.
When Might a Doctor Recommend One Over the Other?
The choice generally follows the symptoms. Upper abdominal symptoms — heartburn, reflux, or swallowing difficulty — point toward a gastroscopy, while lower gastrointestinal symptoms — rectal bleeding, altered bowel habit, or a family history of colorectal disease — point toward a colonoscopy. In some cases, particularly where the source of a symptom like anaemia isn't clear, both procedures may be recommended together.
Cancer Screening and Endoscopy
Beyond diagnosing symptoms, both procedures play an important role in cancer screening. Colonoscopy is recommended as part of routine colorectal cancer screening from around age 50, since removing precancerous polyps during the procedure can prevent colorectal cancer from developing. Gastroscopy can help identify early changes associated with stomach or oesophageal cancer in patients with relevant symptoms or risk factors.
Frequently Asked Questions
Both procedures are typically performed under sedation with a competent anaesthetist involved, so most patients feel little to no discomfort during either procedure.
In some cases, particularly where the cause of a symptom such as anaemia isn't clear, both procedures may be recommended together. Whether this is appropriate depends on your individual symptoms and will be discussed with you.
Colonoscopy is recommended as part of routine colorectal cancer screening from around age 50 for average-risk individuals, or earlier if there's a family history of colorectal cancer or polyps.
Before a gastroscopy, you'll generally be asked to avoid eating or drinking for several hours beforehand. Before a colonoscopy, a bowel preparation taken over one to two days is required so the bowel lining can be seen clearly. Exact instructions are explained in full ahead of your procedure.
Not Sure Which Procedure You Need?
Dr Chamisa offers gastroscopy and colonoscopy in Pretoria for both symptom investigation and screening. Book an appointment to discuss which procedure is right for you.
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