A sigmoidoscopy is a brief endoscopic procedure that allows a doctor to examine the lower section of the large intestine, specifically the rectum and the sigmoid colon. This examination uses a thin, flexible tube equipped with a camera to check for issues like polyps, inflammation, bleeding, or cancer. For the doctor to obtain a clear view of the colon lining, the bowel must be completely empty of residual stool. The success and reliability of the results depend entirely on the thoroughness of the preparation, which involves precise dietary changes and cleansing steps. Following instructions exactly is necessary to avoid having the procedure canceled or needing to repeat it due to poor visibility.
The Dietary Timeline
The process of stopping solid food consumption typically begins 24 hours before the scheduled appointment. For instance, if your procedure is set for 9:00 AM on a Tuesday, you must cease eating solid foods by 9:00 AM on Monday and transition immediately to a clear liquid diet. Some regimens recommend beginning a low-fiber diet two to three days before the exam to reduce the bulk of material passing through the digestive tract. Foods high in fiber, such as nuts, seeds, and raw vegetables, should be stopped earlier than other solids, sometimes up to seven days prior.
The strict fasting period, where all liquids are restricted, usually begins several hours before the procedure. Patients are typically instructed to stop drinking any fluids, including clear liquids and water, four hours before the scheduled arrival time. This final restriction ensures the stomach is empty, particularly if sedation is administered during the sigmoidoscopy. Consuming any food or unapproved liquids after the designated cutoff time can result in the cancellation of the procedure.
Understanding the Clear Liquid Diet
A clear liquid diet consists only of liquids you can see through, which are easily digested and leave minimal residue in the colon. The goal is to keep the body hydrated while ensuring the digestive tract is clean. Acceptable options include plain water, clear broth or bouillon, and pulp-free fruit juices like white grape or apple juice.
Patients can also consume plain gelatin (no fruit pieces), popsicles, and clear sports drinks, provided they do not contain red or purple dyes. Liquids with red, purple, or orange coloring must be avoided, as these can be mistaken for blood during the examination. Forbidden items include all dairy products, juices with pulp, alcohol, and solid foods.
Bowel Cleansing Steps
Dietary adjustments are combined with a mechanical cleansing process to flush the lower bowel completely. For a sigmoidoscopy, this often involves taking an over-the-counter laxative, such as Magnesium Citrate, the evening before the procedure. The oral laxative induces watery bowel movements, clearing the colon of residual matter.
The final step involves administering one or two enemas, typically Fleet enemas, immediately preceding the exam. These are small-volume liquid preparations inserted rectally to clean out the end of the colon. The first enema is usually administered about one hour before leaving home, with the second following 30 minutes later, or as specified in the instructions. Proper administration involves inserting the lubricated tip while lying on the left side and attempting to retain the solution for a few minutes before evacuation.
Medication Adjustments and Recovery Planning
Before beginning preparation, patients must discuss all medications, vitamins, and supplements with the prescribing healthcare provider. Certain medications, especially blood thinners like warfarin or clopidogrel, may need to be adjusted or temporarily discontinued up to a week before the procedure to reduce the risk of bleeding. Iron supplements must also be stopped, sometimes for five to seven days, as they can discolor the colon lining and obstruct the view.
Patients taking insulin or other diabetes medications will require dose adjustments due to the fasting and dietary restrictions. Most morning medications, such as those for blood pressure or seizures, can be taken with a small sip of water on the day of the procedure. After the sigmoidoscopy, patients can usually return to their normal diet and activities immediately. Mild cramping and gas are common due to the air introduced into the colon during the exam. If sedation was used, a responsible adult must drive the patient home, and the patient must avoid driving or operating machinery for the rest of the day.