A colonoscopy is an endoscopic medical procedure that allows a physician to visually examine the inner lining of the large intestine (colon) and the rectum. This examination is performed using a long, thin, flexible tube called a colonoscope, which has a tiny camera and light source on its tip. The procedure serves two primary functions: screening average-risk individuals for colorectal cancer and investigating unexplained gastrointestinal symptoms. These symptoms can include chronic diarrhea, abdominal pain, or blood in the stool, which may indicate the presence of inflamed tissue, ulcers, or other abnormalities.
Patient Preparation Before the Day
The success of the colonoscopy relies heavily on adhering to a meticulous preparation regimen designed to completely clear the colon of all solid waste. Several days before the procedure, the patient begins a low-fiber diet, temporarily avoiding foods like whole grains, nuts, seeds, and raw fruits and vegetables. This reduces the amount of residue entering the colon.
The day before the examination, a strict clear liquid diet must be followed, as no solid food is permitted. Acceptable liquids include clear broth, apple juice, water, and sports drinks, but all liquids must exclude red or purple dyes. Ingesting solid food compromises visualization and may require rescheduling.
The most important step is the bowel preparation, which involves drinking a prescribed laxative solution, often split into two doses taken the evening before and the morning of the procedure. This solution induces powerful diarrhea, flushing the gastrointestinal tract and ensuring clean colon walls for inspection. Patients must disclose all current medications to their doctor, especially blood thinners like warfarin or aspirin, as these may need to be paused to reduce the risk of bleeding if a polyp is removed.
Step-by-Step During the Examination
Upon arrival at the facility, an intravenous (IV) line is placed, and sedation is administered to ensure comfort and minimize awareness during the examination. Sedation often ranges from conscious sedation to deeper anesthesia. The patient is typically positioned lying on their left side with their knees drawn toward their chest.
The physician gently inserts the lubricated colonoscope into the rectum and advances it through the large intestine to the cecum. To create a clear viewing space within the collapsed colon, air or carbon dioxide gas is introduced to inflate the bowel walls. This insufflation allows the physician to see the inner lining clearly on a video monitor connected to the scope’s camera.
The most thorough part of the examination occurs as the colonoscope is slowly withdrawn, allowing for a detailed inspection of the mucosal surface. If abnormal growths, called polyps, are identified, they are typically removed immediately in a procedure known as a polypectomy. Small instruments are passed through the scope to grasp, snare, or cauterize the base of the polyp, removing it entirely to prevent its potential progression into cancer. If suspicious tissue cannot be fully removed, a small sample (biopsy) is taken for laboratory analysis.
Immediate Recovery and Understanding Results
After the examination, the patient is moved to a recovery area where a nurse monitors them as the effects of the sedation wear off. The initial wake-up period may involve feeling groggy or disoriented, which is a normal consequence of the anesthetic medications. A common immediate side effect is bloating and the urge to pass gas, as the body eliminates the air or carbon dioxide introduced during the procedure.
Due to the lingering effects of sedation, a responsible adult must escort the patient home; driving, operating machinery, or making major decisions is prohibited for the remainder of the day. Discharge instructions advise the patient to rest and gradually reintroduce a normal diet, starting with light, easily digestible foods. Minor symptoms like mild abdominal cramping or a small amount of rectal bleeding after a polypectomy are expected and resolve quickly.
The physician usually communicates the immediate visual findings before the patient is discharged, noting if the colon was clear or if polyps were removed. Any tissue samples or polyps are sent to a pathology laboratory for detailed analysis. These formal results, which determine if the polyps were benign or precancerous, typically become available within a few days to two weeks. The results of this analysis will determine the recommended interval for the patient’s next screening, which may be ten years for a completely clear colon or sooner if certain types of polyps were found.