A colonoscopy is a medical procedure used to examine the lining of the large intestine, or colon, using a colonoscope. This thin, flexible tube has a small camera and light at its tip, allowing a physician to view the entire colon on a video screen. The primary purpose of this examination is screening, which involves looking for and removing precancerous growths called polyps. It is also used to investigate symptoms like unexplained bleeding or chronic diarrhea.
Preparing for the Procedure
The most intensive part of the entire colonoscopy process is the bowel preparation, which is necessary to ensure the colon is completely clean. A clean colon allows the physician to clearly see the mucosal lining and detect small polyps. Preparation typically begins several days before the procedure with dietary changes to reduce the amount of residue in the gut.
Approximately three to five days before the procedure, patients are usually instructed to follow a low-fiber diet. This means avoiding foods like nuts, seeds, whole grains, and raw fruits and vegetables, which helps prevent these items from remaining in the colon and obstructing the view. The day before the colonoscopy, the diet must change to exclusively clear liquids, such as water, broth, clear juices without pulp, and gelatin. Patients must avoid any liquids with red, blue, or purple dyes.
The laxative regimen, often referred to as “the prep,” is usually a prescription solution taken in two doses. The first dose is typically consumed the evening before the procedure, and the second dose is taken early on the morning of the colonoscopy. Completing the entire prescribed volume is critical for achieving a successful clean colon, which is indicated by the passing of clear or light yellow liquid. Failing to complete the prep may result in an inadequate view, potentially leading to missed polyps or the need to reschedule the procedure.
Patients must also receive specific instructions from their physician regarding medication adjustments in the days leading up to the procedure. Blood-thinning medications, such as aspirin or warfarin, may need to be temporarily discontinued to reduce the risk of bleeding if polyps are removed. Individuals with diabetes may need to adjust their insulin or oral medication dosages due to the fasting and dietary restrictions. Patients must consult with the prescribing physician before making any changes to these medications.
What Happens During the Colonoscopy
Upon arrival at the facility, the patient checks in and a nurse reviews their medical history, confirms the procedure, and monitors baseline vital signs. An intravenous (IV) line will be started to administer fluids and the sedative medication. The use of sedation is standard practice to ensure patient comfort and tolerance during the examination.
Most colonoscopies use either moderate sedation or deep sedation, which often involves the drug propofol. Propofol is a short-acting anesthetic that provides deep sedation, meaning the patient is typically asleep and unaware of the procedure. An anesthesia professional or a trained nurse usually administers and monitors the sedation throughout the procedure.
Once the patient is sedated, the physician inserts the colonoscope through the rectum and advances it through the large intestine to the cecum, the beginning of the colon. The colon is gently inflated with air or carbon dioxide (CO2) to open the walls and allow for a clear view of the lining. As the scope is slowly withdrawn, the physician carefully examines the colon lining for any abnormalities. If polyps are identified, they are usually removed immediately using a technique called polypectomy, which involves a wire loop or snare passed through the scope. The polyps are then retrieved and sent to a lab for biopsy.
Immediate Recovery and Discharge
After the procedure is complete, the patient is moved to a recovery area where the effects of the sedation begin to wear off. The recovery period typically lasts between 30 and 60 minutes as the patient wakes up fully. Patients commonly experience feelings of bloating, gas, or mild cramping. This discomfort is caused by the air or CO2 that was used to inflate the colon during the examination, which the body will expel naturally.
Before discharge, a nurse will review post-procedure instructions, which include the strict requirement of having a responsible adult present to drive the patient home. The effects of the sedation prevent the patient from legally driving or operating machinery for the remainder of the day. Patients are also advised to refrain from making any important decisions or signing legal documents for 24 hours.
Most patients can resume their normal diet immediately after returning home, unless the physician provides specific, personalized instructions. Normal activities, such as work or exercise, can typically be resumed the following day. The patient will receive preliminary results from the physician before leaving the facility, usually covering whether the colon was clear or if any polyps were removed.
Understanding Your Results and Follow-up Screening
The physician will provide a preliminary assessment immediately after the procedure, indicating if the colon was clear or if polyps were discovered and removed. The more detailed, definitive results come from the biopsy of any removed polyps, which a pathologist examines under a microscope. These final results, which determine if the polyps were benign (non-cancerous) or contained cancerous cells, are usually available within a few days to a week.
The findings of the colonoscopy directly determine the recommended interval for the next screening. If the colon is completely clear, the standard follow-up is generally a repeat screening in ten years. If polyps were found, the surveillance interval shortens to monitor for new growth.
For example, finding one or two small, low-risk adenomas may lead to a recommendation for the next colonoscopy in seven to ten years. However, the presence of larger polyps, multiple polyps, or polyps with high-risk features usually warrants a shorter follow-up, often three to five years. This ensures the colon remains clear.