A small bowel follow through is a specialized imaging test that uses real-time X-rays, known as fluoroscopy, to visualize the entire length of the small intestine. This examination is designed to assess the movement, structure, and condition of the approximately twenty feet of bowel located between the stomach and the large intestine. To make the internal lining of the small bowel visible on the X-ray images, a patient swallows a liquid contrast medium, most commonly a chalky white substance called barium sulfate. The barium coats the intestinal walls, allowing the radiologist to track its path and identify areas that may be causing digestive symptoms. This non-invasive procedure is a valuable diagnostic tool for evaluating unexplained abdominal pain, chronic diarrhea, or significant weight loss.
Preparing for the Examination
Specific preparation steps are required to empty the digestive tract and ensure clear images. The most common requirement is strict fasting, typically eight to twelve hours before the appointment, meaning no food or drinks, including water, after midnight the night before. Patients may also be asked to follow a low-residue diet the day before, limiting fiber and foods that leave residue. While most routine oral medications can be taken with a small sip of water, any medications that affect bowel motility, such as certain pain relievers or laxatives, should be discussed with the ordering physician beforehand. Following these instructions is important because remaining food particles can obscure the view, potentially leading to an incomplete study.
The Steps of the Procedure
The examination begins with the patient lying on an X-ray table, drinking two or more cups of liquid barium sulfate contrast agent. Although usually flavored, the solution is often thick or milkshake-like. Using a fluoroscope, which projects a continuous X-ray image, the radiologist watches the barium pass from the stomach into the duodenum, the first section of the small intestine.
After initial X-ray images are taken, the patient waits, sometimes lying on their right side to help gravity move the barium into the small intestine. Since transit time varies significantly, the procedure can take one to five hours. During this waiting period, interval X-ray images are taken every 15 to 30 minutes to document the barium’s progression.
Throughout the process, the radiologist periodically uses a compression paddle or their hand to gently press on the abdomen. This pressure separates overlapping loops of the small intestine, ensuring the barium thinly coats the mucosal lining for better detail. The procedure is complete once the barium reaches the terminal ileum, the final segment of the small intestine, and begins entering the large intestine.
What the Radiologist Looks For
The goal of the small bowel follow through is to visualize the internal architecture of the intestinal tract, made visible by the barium coating the mucosa. The radiologist examines the images for abnormal changes in the size, shape, and pattern of the small intestine’s loops. They also observe peristalsis (movement) to assess if the muscles are effectively propelling the contrast forward.
The radiologist looks for specific findings, including:
- Areas of narrowing, known as strictures, which can be caused by scar tissue from inflammation or past surgery.
- Evidence of inflammation, such as a thickened bowel wall or a cobblestone appearance of the lining, characteristic of conditions like Crohn’s disease.
- Obstructions or blockages that prevent the normal flow of the contrast.
- Masses, polyps, or ulcers that appear as filling defects or irregularities in the barium column.
Post-Procedure Expectations
Once the final X-rays are taken, the patient can usually resume their normal diet and activities immediately. The most important action is to significantly increase fluid intake for the next 24 to 48 hours. Since the barium is not absorbed and must pass through the digestive system, high fluid consumption helps flush it out and prevent constipation.
Patients should anticipate a temporary change in stool color; the barium will turn the feces white or light gray until it has completely left the body, typically within a few days. If discomfort or inability to pass stool persists after a couple of days, the patient should contact their doctor for advice on safe laxatives. The radiologist analyzes the images and sends a report to the ordering physician, who reviews the findings and discusses the results with the patient, generally within one to ten business days.