Overview
A colonoscopy is a procedure used to examine the inside of the colon and rectum. A trained healthcare professional passes a flexible tube with a light and camera through the anus to look for changes such as polyps, inflammation, ulcers, bleeding, or cancer. It may be done as a screening test, to investigate symptoms, or to follow up on an abnormal result from another test.
Key Symptoms
A colonoscopy may be recommended if a person has symptoms such as blood in the stool, ongoing diarrhea or constipation, unexplained abdominal pain, unexplained weight loss, or iron-deficiency anemia. It may also be used after a positive stool-based screening test. Some people have a colonoscopy even when they feel well, as part of routine screening based on age or personal risk.
Causes and Risk Factors
Reasons for colonoscopy include checking for colorectal cancer, looking for colon polyps, evaluating inflammatory bowel disease, or finding the cause of bleeding or changes in bowel habits. A person may be more likely to need this test if they are older, have a personal or family history of colorectal cancer or polyps, have certain inherited conditions, or have long-term bowel inflammation. Local screening recommendations vary by country and health system.
Who Is Affected
People of many ages may need a colonoscopy, but it is more commonly used in middle-aged and older adults for screening. Younger people may need it if they have symptoms, inflammatory bowel disease, a strong family history, or another higher-risk condition. Access, preparation instructions, and sedation practices can differ between countries and healthcare settings.
Prevention
Colonoscopy can help prevent colorectal cancer by finding and removing some polyps before they become cancerous. Not every polyp turns into cancer, but finding them can lower future risk. Screening schedules depend on a person's age, test findings, family history, and local guidance.
Diagnosis and Tests
Before the procedure, the bowel must be emptied using a special preparation plan, and patients are usually asked to follow diet and medication instructions carefully. During the test, air or carbon dioxide is used to open the colon so the lining can be seen. If needed, the clinician may take biopsies or remove polyps for laboratory testing. Afterward, a person may have bloating or gas and may need someone to accompany them home if sedating medicines were used.
Living With It
Many people feel worried or embarrassed before a colonoscopy, but it is a routine medical procedure in many healthcare systems. Understanding the steps ahead of time and following the preparation instructions closely can make the test more useful and reduce the chance of needing it repeated. Results may be available right away for visual findings, while biopsy results often take longer.
Diet and Lifestyle
The most important lifestyle step for a colonoscopy is to follow the bowel preparation and diet instructions exactly as given by the healthcare team. This often includes temporary changes to what you eat and drink before the test. Usual medicines may also need review in advance, especially blood thinners, diabetes medicines, or iron supplements, so it is important to ask the care team for individualized instructions.
When to Seek Medical Care
Contact a healthcare professional if you have symptoms that led to the test, questions about how to prepare, or problems completing the bowel preparation. After the procedure, seek medical advice if you have persistent vomiting, fever, increasing abdominal pain, ongoing dizziness, or significant rectal bleeding. Also seek advice if you do not understand your results or follow-up plan.
When It May Be an Emergency
Emergency care may be needed after a colonoscopy if there is severe abdominal pain, heavy rectal bleeding, fainting, trouble breathing, chest pain, or a swollen, hard abdomen. These symptoms can suggest a serious complication and should not be ignored. Follow local emergency guidance or go to the nearest emergency department.
Questions to Ask a Healthcare Professional
You may want to ask why the colonoscopy is being recommended, how to prepare, whether any of your usual medicines need adjustment, and what to expect on the day of the test. It can also help to ask about possible risks, when results will be ready, and whether you will need someone to take you home. If screening is the reason for the test, ask how often follow-up testing may be needed.