Small bowel feces sign

Last revised by Daniel J Bell on 6 Feb 2024

The small bowel feces sign can be observed on abdominal CT. The sign has been described as a finding specific for small bowel obstruction or another severe small bowel abnormality (e.g. metabolic or infectious disease).

While the reported prevalence of the sign in small bowel obstruction is low (7-8%) 1, the combination of small bowel feces sign and moderate to severe bowel dilatation is fairly suggestive of obstruction, particularly when associated with distal bowel collapse 7. Interestingly, the small bowel feces sign has been demonstrated to be more frequent on CT in patients without small bowel obstruction than in those patients with small bowel obstruction 7. In patients presenting with acute abdominal pain, the most common location for this sign was in the distal small bowel, in both patients with and without associated obstruction 7.

Defined by the presence of particulate feculent material mingled with gas bubbles in the lumen of the small intestine (resembling colonic content on CT), it is believed to be the result of delayed intestinal transit caused by incompletely digested food, bacterial overgrowth, or increased water absorption of the distal small bowel contents due to obstruction 1.

The small bowel feces sign is most often present in distal small intestine loops, for a length of between 4 and 200 cm.

The small bowel feces sign has shown a high specificity for subacute or low-grade small bowel obstruction because, in a progressively developing obstruction with slowed intestinal transit, there is enough time for increased water absorption to subsequently form the feces-like intestinal content. Recognition is important to prevent a delay in medical intervention. Since the sign is usually seen immediately proximal to the level of obstruction (i.e. transition point), it may be helpful in recognition of the exact site and cause 6.

  • non-obstructive causes of abdominal pain 7

  • small bowel obstruction caused by a phytobezoar, usually necessitating surgery 4,5

Detection of the small bowel feces sign should prompt you to:

  • look for possible bowel dilatation and/or distal collapse 6,7

  • distinguish it from phytobezoar (rare), using lung windows and length measurements. Features favoring a phytobezoar include 4,5:

    • higher grade of obstruction

    • absence of hazy mesentery and interloop ascites

    • length <~10 cm

    • mean attenuation less than ~-12 HU

The CT small bowel feces sign was first described in 22 adult patients in 1995 by William W Mayo Smith and colleagues at Massachusetts General Hospital 2.

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