A small bowel follow through (SBFT) is an imaging test that uses X-rays and a contrast liquid to produce detailed pictures of your small intestine. You drink a chalky liquid, typically barium sulfate, and a radiologist takes a series of X-ray images as it travels through the roughly 20 feet of small bowel. The whole process usually takes between one and two hours, though it can range from 15 minutes to as long as five hours depending on how quickly the contrast moves through your system.
What the Test Is Used For
The small bowel follow through has long been used to detect obstructions, masses, anatomical abnormalities, and other problems in the small intestine. It shows the size and shape of your small bowel and reveals how material moves through it. When movement is blocked or abnormally slow, the images make that visible in real time.
One of its most common uses is evaluating inflammation in the terminal ileum, the last stretch of the small intestine where Crohn’s disease frequently appears. The images can reveal wall thickening, ulcerations, strictures (narrowed segments), and fistulas (abnormal connections between the intestine and other structures). These findings help doctors distinguish between Crohn’s disease, ulcerative colitis, and other forms of inflammatory bowel disease.
The test is also used to investigate small bowel obstructions. In these cases, doctors sometimes use a water-soluble contrast called Gastrografin instead of barium. Gastrografin has an osmotic effect, meaning it draws water into the intestine, which can actually help resolve partial blockages while simultaneously diagnosing them. Research published in Cureus found that using SBFT early in suspected small bowel obstructions reduced both hospital stays and costs.
How the Procedure Works
The test takes place in a fluoroscopy suite, which is essentially an X-ray room with a screen that lets the radiologist watch the contrast liquid move through you in real time. You’ll stand or lie on a tilting table, and the process follows a straightforward sequence.
First, you drink one or two cups of the contrast liquid. Barium sulfate is thick and chalky, and most people find the taste and texture unpleasant but manageable. Some facilities flavor it to make it more tolerable. After you drink it, the radiologist takes X-ray images at regular intervals, typically every 15 to 30 minutes, tracking the barium as it passes from your stomach through the three sections of the small intestine: the duodenum, jejunum, and ileum.
Between images, you’ll usually wait in a nearby area. The radiologist may ask you to change positions or press gently on your abdomen to spread the barium and get clearer views of specific loops of bowel. When the contrast reaches the end of the small intestine and enters the large intestine, the test is complete. The mean transit time across studies is about 84 minutes, and roughly 83% of patients finish in under two hours.
How to Prepare
You’ll typically need to fast for at least 8 to 12 hours before the test, which means nothing to eat or drink after midnight if your appointment is in the morning. An empty stomach and intestines give the barium a clean background to work against, producing much sharper images. Your doctor may also ask you to stop taking certain medications that slow gut motility, since these can artificially delay transit and extend the test.
Wear comfortable clothing without metal buttons, zippers, or belt buckles near your abdomen. You’ll likely be asked to change into a hospital gown. Leave jewelry at home.
What to Expect Afterward
There’s no recovery period. You can eat, drink, and return to normal activities immediately after the test. However, you should drink extra water for the rest of the day to help flush the barium through your system. Barium can cause constipation if it sits in the colon too long, and staying well hydrated is the simplest way to prevent that.
Your stools will appear white or light-colored for a day or two as the barium passes. This is completely normal and not a reason for concern. If you go more than two days without a bowel movement after the test, or if you develop significant abdominal pain or bloating, contact your doctor, as retained barium can occasionally cause a blockage in people who are already prone to constipation.
Radiation Exposure
Because the test involves repeated X-ray images over an extended period, it delivers more radiation than a single standard X-ray. The exact dose depends on how many images are needed and how long the contrast takes to transit. For context, fluoroscopic GI studies generally deliver effective doses in the range of a few millisieverts, comparable to about one to three years of natural background radiation. This is considered low risk for a diagnostic procedure, but it’s one reason doctors weigh the benefits against alternatives, especially for younger patients or those who need repeated imaging over time.
How It Compares to Other Tests
CT enterography and MR enterography have largely replaced the small bowel follow through at many medical centers, particularly for evaluating Crohn’s disease. These cross-sectional imaging techniques can visualize the bowel wall itself, not just the interior channel, which means they detect inflammation, abscesses, and complications outside the intestinal wall that an SBFT would miss entirely.
CT enterography is faster and provides more detailed images, but it involves higher radiation doses. MR enterography uses no radiation at all, making it the preferred option for younger patients and those requiring frequent monitoring. Capsule endoscopy, where you swallow a tiny camera that photographs the intestinal lining as it passes through, offers direct visualization but can’t be used when a blockage is suspected.
Despite these newer options, the SBFT remains useful in specific situations. It’s widely available, relatively inexpensive, and effective for evaluating how material moves through the small bowel over time. For suspected partial obstructions, particularly when paired with water-soluble contrast, it serves both a diagnostic and potentially therapeutic role that other imaging methods don’t offer.