A colonoscopy is a medical examination used to view the inside of the large intestine, which includes the colon and rectum. The procedure uses a colonoscope, a long, thin, flexible tube with a light and a small video camera at its tip. The instrument is inserted into the rectum and guided through the colon.
For a clear view, the bowel must be empty, requiring preparation that involves a liquid diet and laxatives. During the 30 to 60-minute examination, air or carbon dioxide is pumped into the colon to inflate it. This inflation provides the physician with a better view of the colon’s lining on an external monitor.
Early Cancer Detection
A primary function of a colonoscopy is the early detection of colorectal cancer. The procedure allows a physician to directly visualize the colon’s lining, identifying abnormal tissues that other screening methods might miss. This direct visual inspection makes it a benchmark for colorectal cancer screening.
If suspicious tissue is found, the colonoscope has a channel for specialized instruments. This allows the physician to perform a biopsy by taking a small tissue sample for laboratory analysis. Finding cancer in its initial stages, before it can grow or spread, significantly improves treatment effectiveness.
This ability to both see and sample tissue in one procedure is a distinct advantage. While a virtual colonoscopy can create images of the colon, it does not permit immediate tissue collection. Any abnormalities found with other methods would require a follow-up colonoscopy for investigation.
Preventing Cancer Development
A colonoscopy also plays a role in preventing cancer from developing. This is achieved through the detection and removal of polyps, which are small growths on the inner lining of the colon or rectum. While most polyps are benign, certain types can transform into cancer over time.
The development of cancer from a polyp is a slow process, often taking several years. A colonoscopy interrupts this by allowing for the immediate removal of these precancerous growths. During the examination, a physician can remove polyps in a procedure known as a polypectomy.
This proactive removal of polyps is a benefit of the screening. Once removed, the polyps are sent to a laboratory for analysis to determine if they are noncancerous, precancerous, or contain cancerous cells. This information helps guide any necessary follow-up care and can effectively stop cancer before it starts.
Investigating and Diagnosing Other Bowel Conditions
A colonoscopy is a valuable diagnostic tool for many bowel conditions unrelated to cancer. The direct view of the colon can help pinpoint the cause of unexplained symptoms, such as:
- Chronic abdominal pain
- Changes in bowel habits like persistent diarrhea or constipation
- Rectal bleeding
- Unexplained weight loss
The procedure is highly effective in diagnosing inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis. These chronic conditions are characterized by inflammation of the digestive tract. A colonoscopy reveals the extent and pattern of inflammation, helping to distinguish between the two conditions.
The examination can also identify other structural issues, such as diverticulosis. This is a condition where small pouches, or diverticula, bulge outward through weak spots in the colon wall. By providing a comprehensive view of the large intestine, a colonoscopy offers a thorough assessment of bowel health.