A colonoscopy is often feared, and sometimes joked about, but it is an important procedure in maintaining good health when we experience digestive symptoms that concern us and as we get older. Understanding what to expect may ease your concerns.
What is a colonoscopy?
A colonoscopy is a procedure used to see inside the colon and rectum. Colonoscopy can detect inflamed tissue, ulcers and abnormal growths. The procedure is used to look for early signs of colorectal cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus and weight loss.
What are the colon and rectum?
The colon and rectum are the two main parts of the large intestine.
The colon and rectum are the two main parts of the large intestine. Although the colon is only one part of the large intestine, because most of the large intestine consists of colon, the two terms are often used interchangeably. The large intestine is also sometimes called the large bowel.
Digestive waste enters the colon from the small intestine as a semisolid. As waste moves toward the anus, the colon removes moisture and forms stool. The rectum is about six inches long and connects the colon to the anus. Stool leaves the body through the anus. Muscles and nerves in the rectum and anus control bowel movements.
When to start having a routine colonoscopy
A routine colonoscopy, to look for early signs of cancer, should begin at age 50 for most people—earlier if there is a family history of colorectal cancer, a personal history of inflammatory bowel disease or other risk factors. Based on your family history and your symptoms, the doctor can advise you about how often to get a colonoscopy.
Preparing for a colonoscopy
The doctor usually provides written instructions about how to prepare for colonoscopy. Generally, all solids must be emptied from the gastrointestinal tract by following a clear liquid diet for one to three days before the procedure. Patients should not drink beverages containing red or purple dye. Acceptable liquids include:
A laxative or an enema may be required the night before a colonoscopy. A laxative is medicine that loosens stool and increases bowel movements, usually swallowed in pill form or as a powder dissolved in water. An enema is performed by flushing water, or sometimes a mild soap solution, into the anus using a special wash bottle.
You should inform the doctor of all medical conditions and any medications, vitamins, or supplements taken regularly, including:
Driving is not permitted for 24 hours after a colonoscopy to allow the sedative time to wear off. Before the appointment, you should make plans for someone to drive you home.
During a colonoscopy
Examination of the large intestine
During a colonoscopy, patients lie on their left side on an examination table. In most cases, a light sedative, and possibly pain medication, helps keep patients relaxed. Deeper sedation may be required in some cases. The doctor and medical staff monitor vital signs and attempt to make patients as comfortable as possible.
During a colonoscopy, patients lie on their left side on an examination table.
The doctor inserts a long, flexible, lighted tube called a colonoscope, or scope, into the anus and slowly guides it through the rectum and into the colon. The scope inflates the large intestine with carbon dioxide gas to give the doctor a better view. A small camera mounted on the scope transmits a video image from inside the large intestine to a computer screen, allowing the doctor to carefully examine the intestinal lining. The doctor may ask you to move periodically so the scope can be adjusted for better viewing.
Once the scope has reached the opening to the small intestine, it is slowly withdrawn and the lining of the large intestine is carefully examined again. Bleeding and puncture of the large intestine are possible but uncommon complications of colonoscopy.
Removal of polyps and biopsy
A doctor can remove growths, called polyps, during colonoscopy and later test them in a laboratory for signs of cancer. Polyps are common in adults and are usually harmless. However, most colorectal cancer begins as a polyp, so removing polyps early is an effective way to prevent cancer.
The doctor can also take samples from abnormal-looking tissues during colonoscopy. The procedure, called a biopsy, allows the doctor to later look at the tissue with a microscope for signs of disease.
The doctor removes polyps and takes biopsy tissue using tiny tools passed through the scope. If bleeding occurs, the doctor can usually stop it with an electrical probe or special medications passed through the scope. Tissue removal and the treatments to stop bleeding are usually painless.
A colonoscopy usually takes 30 to 60 minutes. Cramping or bloating may occur during the first hour after the procedure. The sedative takes time to completely wear off. You may need to remain at the hospital for one to two hours after the procedure. Full recovery is expected by the next day. Discharge instructions should be carefully read and followed. If you develop any of these rare side effects, contact your doctor immediately:
Points to Remember
Source: National Digestive Diseases Information Clearinghouse, National Institutes of Health
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