A flexible sigmoidoscopy is a medical procedure used to examine the lower part of the large intestine, specifically the rectum and the sigmoid colon. It uses a sigmoidoscope, a slender, flexible tube equipped with a light and camera, to look for signs of inflammation, polyps, or cancer. Proper bowel preparation is necessary because the colon lining must be completely visible for the procedure to be successful. The preparatory steps focus on cleansing the lower bowel and are distinct from a full colonoscopy.
Dietary and Medication Adjustments Before Prep Day
Preparation for a sigmoidoscopy often begins several days before the main cleansing protocol with adjustments to diet and medication. Dietary preparation involves shifting to a low-residue, low-fiber diet, typically starting one to three days prior to the procedure. This limits the bulk of waste passing through the intestines, making the final cleansing more effective. High-fiber foods, such as whole grains, nuts, seeds, popcorn, and raw fruits and vegetables, should be temporarily avoided.
Medication review must happen in consultation with the prescribing physician. Blood-thinning medications (including NSAIDs like ibuprofen or naproxen) may need adjustment to reduce bleeding risk if tissue samples are taken. Patients managing diabetes with insulin or oral medications require specific instructions, as the change in diet can affect blood sugar levels.
Supplements containing iron or fiber may also need to be paused, as they can interfere with visual clarity inside the colon. Patients must receive individualized guidance before making any changes to prescription medications. Following these instructions helps ensure safety and contributes to a clear view during the examination.
The Required Bowel Cleansing Protocol
The day before the procedure, patients transition fully to a clear liquid diet. A clear liquid is defined as any liquid you can see through. Permitted options include:
- Water
- Clear broth
- Plain gelatin
- Clear sports drinks
- Strained fruit juices without pulp
Avoid liquids or gelatin colored with red or purple dyes, as they can be mistaken for blood during the examination.
Hydration is encouraged throughout the clear liquid phase, often by drinking eight ounces of liquid every hour while awake. This continuous fluid intake flushes the digestive system and prevents dehydration. The specific cleansing method for a sigmoidoscopy is typically less extensive than a full colonoscopy preparation, often focusing on the lower colon only.
Direct bowel cleansing usually involves one or two over-the-counter enemas (such as a saline laxative enema) administered shortly before the procedure. The first enema is inserted rectally and held for five to ten minutes before being expelled, stimulating the lower bowel to empty. A second enema is typically repeated to ensure the area is sufficiently clean for visualization. The goal is for the expelled fluid to be clear or only slightly yellow, indicating a successful preparation. Some protocols may also include an oral laxative taken the evening before, but the use of enemas immediately before the appointment is the defining feature of the sigmoidoscopy prep.
What Happens During the Sigmoidoscopy
Upon arrival, the patient changes into a gown and is positioned on their left side, often with knees drawn toward the chest. The provider performs a brief digital rectal exam to lubricate the area before inserting the scope. The sigmoidoscope, a long, flexible tube, is then gently guided through the rectum and into the sigmoid colon.
The scope transmits a video image to a monitor, allowing the doctor to examine the inner lining for abnormalities. To improve visualization, air or carbon dioxide is often insufflated into the colon, temporarily expanding the bowel walls. This insufflation may cause a feeling of pressure, bloating, or cramping during the procedure.
A sigmoidoscopy typically does not require deep sedation, and many patients have the procedure without relaxation medication. The examination is brief, often lasting only 10 to 20 minutes. If polyps or tissue samples (biopsies) are taken, specialized instruments are passed through the scope, and the patient usually does not feel this removal.
Recovery and Receiving Initial Results
Immediately following the sigmoidoscopy, patients move to a recovery area and can typically get dressed right away if no sedation was used. The most common side effects are gas, bloating, and mild abdominal cramping, resulting from the air introduced during the procedure. Walking around and passing gas can help to alleviate this discomfort quickly.
Since deep sedation is avoided, most patients can resume normal activities, including driving, immediately. They can also return to their regular diet right away, though some may prefer a light meal initially. If any biopsies were taken, there may be a small amount of light rectal bleeding, which should resolve within a day or two.
The healthcare provider often shares initial findings, such as polyps or inflammation, with the patient before they leave. If polyps or tissue samples were collected, specimens are sent to a laboratory for analysis; final results usually take several days or up to two weeks. A follow-up plan to discuss these pathology results is typically arranged at the time of discharge.