How you prepare

Before a flexible sigmoidoscopy exam, you'll need to empty your colon. Any residue in your colon may obscure the view of your colon and rectum during the exam.

To empty your colon, follow your doctor's instructions carefully. You may be asked to:

• Follow a special diet the day before the exam. Your doctor may ask you not to eat the day before the exam. Drinks may be limited to clear liquids — plain water, broth, carbonated beverages, and tea and coffee without milk or cream. You may be asked not to eat or drink anything after midnight the night before the exam.
• Take a laxative the night before the exam. If your doctor asks you to take a laxative, it will be in either pill or liquid form.
• Use an enema kit. You will need to use an over-the-counter enema kit — typically a few hours before the exam — to empty your colon. You may be asked to take two enemas.
• Adjust your medications. Remind your doctor of your medications at least a week before the exam — especially if you have diabetes, if you take medications or supplements that contain iron, or if you take aspirin or other blood thinners. You may need to adjust your dosages or stop taking the medication temporarily.