Colonoscopy or Endoscopy: Differences and When Each Is Performed
Decision Guide · Silo Endoscopy · Colombia 2026
Colonoscopy or endoscopy: differences, when each is performed and how to choose
Did your doctor order a colonoscopy or an endoscopy, and you don't know which is which? This guide explains the exact difference, what each procedure examines, when one or the other is indicated, and how to prepare
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GSMED Imaging technical team — endoscopy equipment in Colombia
Based on: ASGE Practice Guidelines (colonoscopy and upper endoscopy 2025), ESGE Guidelines 2023, Colombian Society of Gastroenterology, MSD Manual Professional 2025, and HIC Colombia endoscopy protocols.
During the consultation with the gastroenterologist, two words come up that cause confusion: "endoscopy" and "colonoscopy". Are they the same? Which is more uncomfortable? What is each one used for? The quick answer: endoscopy (upper) looks at the upper digestive tract — from the mouth to the duodenum; colonoscopy looks at the large intestine — from the anus to the terminal ileum. They are different procedures, with different preparations, and they address different clinical questions.
1. The fundamental difference in one image
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Upper endoscopy (gastroscopy)
The endoscope enters through the mouth. It evaluates: esophagus, stomach, and duodenum (the first 30 cm of the small intestine). Endoscope length: ~1 meter. Duration: 10–20 minutes. Performed with light or conscious sedation. No bowel preparation — only a 6–8 hour fast. Also called upper gastrointestinal endoscopy (UGIE) or gastroscopy.
→ Enters through the mouth · Looks up · Fasting only
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Colonoscopy
The colonoscope enters through the anus. It evaluates: rectum, sigmoid colon, descending colon, transverse colon, ascending colon, and terminal ileum (the last segment of the small intestine). Colonoscope length: ~1.6 meters. Duration: 20–60 minutes. Requires bowel preparation the day before (laxative) to completely clean the colon.
→ Enters through the anus · Looks down · Requires bowel preparation
2. When each is ordered — decision guide
| Symptom / Indication | Upper endoscopy? | Colonoscopy? |
|---|---|---|
| Pain in the pit of the stomach (epigastrium) | Yes — first choice | No — the stomach is not seen with colonoscopy |
| Chronic gastroesophageal reflux (GERD) | Yes — evaluates Barrett's esophagus | No |
| Vomiting blood (hematemesis) | Yes — emergency | No |
| Rectal bleeding (blood in the stool) | Not necessarily | Yes — first choice |
| Colorectal cancer screening (>45 years) | No | Yes — every 10 years if normal |
| Difficulty swallowing (dysphagia) | Yes — evaluates esophagus | No |
| Chronic change in bowel habits | Sometimes — if there are upper symptoms | Yes — rules out colon pathology |
| Iron deficiency anemia with no known cause | Yes — there may be occult upper bleeding | Yes — occult colon bleeding |
| Family history of colorectal cancer | No | Yes — screening starting at 40 years |
| Follow-up of colon polyps | No | Yes — interval depends on polyp type |
| Confirmed H. pylori infection | Yes — gastric biopsy for histology | No |
3. Preparation — the major practical difference
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Preparation for upper endoscopy
Fast for 6–8 hours before the procedure — no food, no drinks (except small sips of water for essential medications). No laxative or bowel preparation required. You can eat normally the day before. On the day of the procedure: arrive fasting, bring someone to take you home if you receive sedation.
→ Fasting only · No laxative · Easy
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Preparation for colonoscopy
Liquid diet the day before (only clear liquids: water, broths, clear gelatin, pulp-free juices). Osmotic laxative (polyethylene glycol or similar) the evening before — produces multiple bowel movements that completely clean the colon. It is essential — a dirty colon forces the examination to be repeated. On the day of the procedure: fasting from midnight.
→ Previous liquid diet · Mandatory laxative · 12–24 h process
Why colonoscopy preparation is so important Colonoscopy is the only screening procedure that can prevent colorectal cancer — not just detect it. But for the gastroenterologist to clearly see the colon mucosa and detect small polyps (which can become cancer in 5–10 years), the colon must be completely clean. A poorly prepared colon prevents the doctor from seeing 25–50% of polyps — negating the procedure's preventive benefit. The uncomfortable preparation is the price of a colonoscopy that actually works.
4. Can both be done on the same day?
Yes. When the doctor needs to evaluate both the upper and lower digestive tract — for example, in iron deficiency anemia with no known cause — they can schedule both procedures in the same session, under the same sedation. The usual order is: first upper endoscopy (which is faster), then colonoscopy. The bowel preparation covers both procedures. This combination saves the patient time, reduces the cumulative risk of sedation, and optimizes the endoscopy department's resources.
5. Frequently asked questions
How much does colonoscopy and endoscopy cost in Colombia?
In the EPS system, both procedures are covered by the PBS when ordered by the gastroenterologist with a justified indication. In the private sector: upper endoscopy (gastroscopy) ranges from $250,000 to $500,000 COP. Diagnostic colonoscopy between $350,000 and $700,000 COP. Colonoscopy with polypectomy can cost between $500,000 and $1,200,000 COP depending on the number and size of the polyps removed. Biopsy has an additional pathology cost of $80,000–$200,000 COP per sample.
Is colonoscopy very uncomfortable?
With proper sedation, colonoscopy is surprisingly well tolerated — most patients do not remember the procedure. The most uncomfortable part for many is the bowel preparation the day before — taking the laxative produces multiple bowel movements for several hours. The procedure itself under sedation does not cause significant pain. Without sedation (less common in Colombia), there may be discomfort from air distension during the advancement of the colonoscope.
At what age should I have my first screening colonoscopy?
The ASGE 2025 guidelines and the Colombian Society of Gastroenterology recommend starting colorectal cancer screening at 45 years in people with no additional risk factors (it used to be at 50 years — it was moved up due to the increase in colorectal cancer in young adults). If you have a family history of colorectal cancer in a first-degree relative, screening should start 10 years before the earliest diagnosis in the family. If the colonoscopy is normal, the next check-up is in 10 years.
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