Purpose:

1. Screening : Detect colon cancer, polyps, and other abnormalities in asymptomatic individuals.

2. Diagnosis : Investigate symptoms like abdominal pain, bleeding, or changes in bowel habits.

3. Surveillance : Monitor patients with a history of colon cancer, polyps, or inflammatory bowel disease.

Procedure:

1. Preparation : Patient undergoes bowel preparation (laxatives, diet changes) to cleanse the colon.

2. Insertion : The colonoscope is inserted through the rectum and guided through the colon.

3. Examination : The doctor visually examines the inner lining of the colon, removing polyps or taking biopsies as needed.

4. Removal : The colonoscope is slowly withdrawn.

Risks and Complications:

1. Bleeding : From polyp removal or biopsy.

2. Perforation : Hole in the colon.

3. Infection : Rarely, bacteria can enter the bloodstream.

4. Reaction to sedation : Rarely, patients may experience adverse reactions.

Preparation and Aftercare:

1. Bowel preparation : Patient must follow a specific diet and take laxatives to cleanse the colon.

2. Sedation : Patient may receive sedation to relax during the procedure.

3. Monitoring : Patient's vital signs are monitored during and after the procedure.

4. Recovery : Patient can usually go home after the procedure, but may experience some discomfort or bloating.

Screening Guidelines:

1. Average-risk individuals : Start screening at age 45 (American Cancer Society) or 50 (US Preventive Services Task Force).

2. High-risk individuals : Start screening earlier, based on family history, genetic predisposition, or personal history of colon cancer or polyps.