Endoscopy vs Colonoscopy: What Is the Difference?

What is an upper endoscopy (EGD)?

An esophagogastroduodenoscopy — usually just called an upper endoscopy or EGD — uses a thin, flexible tube with a camera that is passed through the mouth, down the esophagus, into the stomach, and into the first section of the small intestine (the duodenum).

Common reasons a gastroenterologist recommends an upper endoscopy:

• Persistent heartburn or acid reflux that is not responding to treatment
• Difficulty swallowing (dysphagia) or food getting stuck
• Unexplained upper abdominal pain, nausea, or vomiting
• Looking for the source of upper GI bleeding (blood in vomit, or very dark, tarry stools)
• Diagnosis or monitoring of conditions like Barrett's esophagus, gastric ulcers, celiac disease, and eosinophilic esophagitis
• Removing a swallowed object

The procedure typically takes five to fifteen minutes. You receive sedation through an IV, so you will not feel or remember most of it. Your throat may be mildly sore for a day after.

What is a colonoscopy?

A colonoscopy uses a longer flexible tube inserted through the rectum and guided through the entire large intestine (colon). It is the most thorough way to examine the colon.

Common reasons a gastroenterologist recommends a colonoscopy:

• Colorectal cancer screening — current guidelines recommend starting at age 45 for average-risk adults 1Ref 1Davidson KW, Barry MJ, Mangione CM, et al. (US Preventive Services Task Force) (2021).Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement.USPSTF recommendation to begin colorectal cancer screening at age 45 for average-risk adults2Ref 2Shaukat A, Kahi CJ, Burke CA, Rabeneck L, Sauer BG, Rex DK (2021).ACG Clinical Guidelines: Colorectal Cancer Screening 2021.ACG guidance on colorectal cancer screening indications and colonoscopy as a primary modality
• Investigating rectal bleeding, blood in the stool, or a significant change in bowel habits
• Removing polyps before they have a chance to become cancerous
• Evaluating or monitoring inflammatory bowel disease (Crohn's disease or ulcerative colitis)
• Unexplained iron-deficiency anemia

Colonoscopy requires a bowel prep the day before — a laxative solution that clears the colon so the camera can see clearly. The procedure itself takes 20–45 minutes under sedation. Most people feel normal the next day 3Ref 3National Institute of Diabetes and Digestive and Kidney Diseases (2023).Colonoscopy.Patient-facing description of colonoscopy procedure, preparation, and recovery.

What is a sigmoidoscopy, and how does it fit in?

A flexible sigmoidoscopy is a shorter version of a colonoscopy that only examines the lower third of the colon (the sigmoid colon and rectum). It does not require full sedation or a complete bowel prep. It can screen for polyps and cancer in the lower colon, but it misses the upper colon. Colonoscopy is more comprehensive and more commonly recommended in the United States today.

Which procedure is right for your symptoms?

The location of your symptoms is the biggest guide:

| Symptom or concern | More likely procedure | |---|---| | Heartburn, regurgitation, difficulty swallowing | Upper endoscopy (EGD) | | Dark, tarry stools; vomiting blood | Upper endoscopy (EGD) — urgent | | Rectal bleeding, bright red blood | Colonoscopy | | Change in bowel habits, cramping | Colonoscopy | | Colorectal cancer screening | Colonoscopy | | Abdominal pain with uncertain location | Depends — clinician will evaluate first |

Sometimes a gastroenterologist will perform both procedures in the same appointment if the source of a problem is unclear. This is not uncommon for unexplained iron-deficiency anemia or GI bleeding, where the source could be in the upper or lower tract.

Both procedures are performed by gastroenterologists — specialists in digestive diseases. Gale can help you find a gastroenterologist and prepare questions for your referral visit.

Are these procedures safe?

Both are considered safe, routine procedures when performed by trained gastroenterologists. Serious complications are uncommon. The main risks include:

• Bleeding — more likely if a polyp is removed during colonoscopy
• Perforation — a small tear in the intestinal wall; rare but serious
• Reaction to sedation — your team monitors you closely throughout

You will need someone to drive you home because of the sedation. Most people return to normal activity the following day.