Colonoscopy Summary Colonoscopy and sigmoidoscopy are procedures that let your doctor look inside your large intestine. They use instruments called scopes. Scopes have a tiny camera attached to a long, thin tube. The procedures let your doctor see things such as inflamed tissue, abnormal growths, and ulcers. Colonoscopy checks your entire colon and rectum. Sigmoidoscopy checks the rectum and the lower colon only. Your doctor may recommend one of these procedures To look for early signs of cancer in the colon and rectum. It may be part of a routine screening, which usually starts at age 50. To look for causes of unexplained changes in bowel habits To evaluate symptoms like abdominal pain, rectal bleeding, and weight loss Your doctor can also remove polyps from your colon during these procedures. You will get written bowel prep instructions to follow at home before the procedure. The bowel prep cleans out the intestine so your doctor can see everything clearly. During a colonoscopy, you get medicines to keep you relaxed. You usually do not need them for a sigmoidoscopy. NIH: National Institute of Diabetes and Digestive and Kidney Diseases National Institute of Diabetes and Digestive and Kidney Diseases Find an Expert ASGE: Find a Doctor American Society for Gastrointestinal Endoscopy National Institute of Diabetes and Digestive and Kidney Diseases National Institute of Diabetes and Digestive and Kidney Diseases Statistics and Research CDC Vital Signs: Colorectal Cancer Centers for Disease Control and Prevention CDC Vital Signs: Colorectal Cancer Tests Save Lives Centers for Disease Control and Prevention Clinical Trials ClinicalTrials.gov: Colonoscopy National Institutes of Health ClinicalTrials.gov: Sigmoidoscopy National Institutes of Health Patient Handouts Colonoscopy National Institute of Diabetes and Digestive and Kidney Diseases Start Here Colonoscopy National Institute of Diabetes and Digestive and Kidney Diseases Colonoscopy American College of Surgeons Understanding Colonoscopy American Society for Gastrointestinal Endoscopy Videos and Tutorials Colonoscopy American Society for Gastrointestinal Endoscopy Colonoscopy National Cancer Institute What Is a Colonoscopy OR-Live What to Expect During a Colonoscopy American College of Gastroenterology Your Radiologist Explains CT Colonography Array Array Colonoscopy Colonoscopy discharge Sigmoidoscopy Virtual colonoscopy Related Issues Colonoscopy: When You Need It — and When You Don’t ABIM Foundation Your Doctor Has Ordered a Colonoscopy: What Questions Should You Ask? American College of Gastroenterology Specifics CT Colonography (Virtual Colonoscopy) Array Flexible Sigmoidoscopy National Institute of Diabetes and Digestive and Kidney Diseases Frequently Asked Questions about Colonoscopy and Sigmoidoscopy American Cancer Society Understanding Bowel Preparation American Society for Gastrointestinal Endoscopy Virtual Colonoscopy National Cancer Institute NIH MedlinePlus Magazine New Ways to Detect Colon Cancer Journal Articles Colonoscopy Latest News Small Study Supports New Stool-Based Colon Cancer Test HealthDay Time to Drop the ‘No-Eating Rule’ Before Colonoscopy? HealthDay Happy Marriage May Prompt Men to Get Colonoscopy HealthDay
