Imaging of the Small Intestine

Barium Contrast Studies

Approximately 16 oz of liquid with very fine, pulverized barium is given to the patient, with serial x-ray films taken before and immediately after the drink, then followed until the terminal ileum is visualized. The test usually is completed in 1 to 2 hours, but some patients have slow transit, and it may take several hours to visualize the terminal ileum. Under fluoroscopy, the radiologist can obtain the many views of the terminal ileal area. The jejunum has characteristic folds, and the ileum is flatter. The jejunum lies primarily in the left side and the ileum in the right side of the abdominal cavity. The terminal ileum has a normal appearance, at times likened to a bird's beak. The jejunum should measure no more than 3 to 3.5 cm in width and the ileum no more than 2.5 to 3 cm in its maximum width. Obstructive lesions, filling defects, irregular mucosa, and the so-called malabsorption pattern (scattered, dilated loops of bowel) can be diagnosed with barium studies. These are described under disease topics in this section.

Enteroclysis, or a small bowel enema, is performed at some centers by inserting a tube into the duodenum and then flooding it with barium contrast solution. This enables the radiologist to better control the timing of images and fluoroscopy so as to identify difficult lesions.