A barium enema is a specialized X-ray examination of the large intestine, or colon, which uses a liquid contrast agent containing the metallic element barium. This contrast material is administered rectally, coating the inner lining of the colon to create a clear silhouette on the X-ray images, helping to reveal any changes or abnormalities. For the radiologist to accurately visualize the colon’s structure and detect issues like polyps or inflammation, the bowel must be completely free of fecal residue. Following the specific preparation instructions is necessary for the procedure to be successful and for the results to be diagnostically reliable.
Multi-Day Dietary Adjustments
The preparation process begins with a dietary modification, typically starting two to three days before the scheduled exam. Patients are instructed to transition to a low-residue or low-fiber diet, which is designed to reduce the volume and frequency of stool production. This initial step aims to minimize the amount of undigested material entering the colon before the active cleansing phase begins.
Acceptable foods during this period include refined carbohydrates, such as white bread, plain pasta, and white rice, along with cooked or canned fruits and vegetables that have been peeled and seeded. Protein sources like eggs and plain, baked, or broiled chicken, fish, or beef are also generally permitted. Conversely, patients must eliminate high-fiber items, including all nuts, seeds, popcorn, whole-grain products, and raw vegetables, as these can leave behind microscopic particles that obscure the X-ray view.
The Bowel Cleansing Regimen
The most intensive part of the preparation occurs on the day immediately preceding the barium enema, centered around a strict clear liquid diet and powerful purgatives. Starting with breakfast, all solid foods are replaced with transparent liquids that leave virtually no residue in the digestive tract. Permitted liquids include clear broth, apple or white grape juice, plain gelatin, popsicles, and water, but patients must avoid any liquids with red, blue, or purple coloring, as these can be mistaken for blood on the X-ray images.
Later in the day, the active bowel cleansing solution is introduced, which often involves a combination of osmotic and stimulant laxatives. A common regimen includes a large volume of polyethylene glycol (PEG) solution or magnesium citrate mixed with a clear sports drink to improve palatability and maintain electrolyte balance. This mixture is consumed over several hours, typically starting in the late afternoon or early evening, prompting a series of watery bowel movements. A stimulant laxative like a bisacodyl tablet is also taken to encourage peristalsis, the muscular contractions that move waste through the colon.
It is advised to remain close to a restroom throughout the evening once the bowel preparation begins, as the effects are rapid and dramatic. Consistent hydration is important during this phase to counteract the fluid loss caused by the laxatives. Patients should continue drinking clear liquids frequently until the rectal discharge is clear and yellowish, indicating a thoroughly cleansed colon.
Final Steps on the Morning of the Exam
The final preparations take place in the hours leading up to the appointment to ensure the colon remains empty. Starting after midnight on the day of the exam, a mandatory nothing-by-mouth (NPO) period begins, meaning no further food or liquid should be consumed. This fasting period is necessary to keep the upper digestive tract empty and reduce the risk of aspiration during the examination.
Patients should review their regular medication schedule with their doctor beforehand, as some drugs, particularly blood thinners or diabetic medications, may need to be temporarily adjusted or skipped. Any necessary morning medications can generally be taken with only a very small sip of water. Upon waking, some protocols require the use of a final cleansing agent, such as a bisacodyl suppository, to evacuate any residual matter from the lower rectum just before leaving for the facility.
For comfort and ease of movement during the procedure, patients should wear comfortable, loose-fitting clothes, preferably a two-piece outfit. Patients should remember to bring their photo identification, insurance information, and any required doctor’s orders or paperwork to the imaging center. These final steps help ensure a smooth check-in process and a successful start to the examination.