Key radiographic finding of bowel obstruction
The hallmark of obstruction, whether mechanical or functional, is dilatation of bowel. The rule of “3s” defines abnormal dilation of the intestine:
- • Small bowel 3 cm or larger
- • Transverse colon 6 cm or larger
- • Cecum 9 cm or larger
Differentiating bowel obstruction from paralytic ileus may be challenging, but several signs are suggestive: prominent abdominal distention, small bowel dilatation, and absence of large bowel dilatation all favor the diagnosis of small bowel obstruction. A “stepladder” configuration of dilated small bowel loops extending from the left upper to the right lower quadrants is highly suggestive. Although previously considered a reliable sign, air fluid levels in the same loop of small bowel at differing heights are not as dependable in diagnosing mechanical small bowel obstruction as initially thought.