Initial imaging modality in a pt with suspected bowel obstruction. Signs of small-bowel obstruction on plain radiographs include multiple air-fluid levels, absence of colonic distention, and a “stepladder” appearance of small-bowel loops.
Should not be performed with barium enhancement when perforated bowel, portal venous gas, or toxic megacolon is suspected.
Used to evaluate the size of bowel:
Normal small bowel is <3 cm in diameter.
Normal caliber of the cecum is up to 9 cm, with the rest of the large bowel up to 6 cm in diameter.