What causes String-of-Beads sign in small bowel on abdominal radiography?
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Answer:
Dilated small bowel loops with trapped air bubbles between the valvulae conniventes (circular folds) in small bowel obstruction (SBO), indicating mechanical obstruction often due to adhesions, hernias, or tumors; may suggest complications like strangulation if associated with mesenteric edema or vascular engorgement. This appearance on abdominal radiography is described as the String-of-Beads sign.
Why is it called so?
Named for the appearance of multiple small, round air bubbles aligned in a linear or oblique row, resembling a string of beads or pearls, seen on upright or decubitus radiographs due to gas trapped in a stepladder configuration along the non-dependent bowel wall. The term String-of-Beads sign reflects this visual analogy.
Pathophysiology
In small bowel obstruction, proximal bowel dilates with fluid and gas; as valvulae conniventes widen and separate, small air bubbles become trapped between the edematous folds on the ventral/non-dependent side, creating the characteristic row of lucencies amidst dilated loops. The finding is related to the anatomy of the small bowel mucosal folds and the distribution of intraluminal gas and fluid during obstruction.
Alternative names: String of pearls sign
Other associated named signs: Small bowel feces sign
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