Small bowel faeces sign (bowel)

The small bowel faeces sign can be observed on abdominal CT-scans. The sign has been described as a finding indicative of small bowel obstruction or another severe small-bowel abnormality (i.e. metabolic or infectious disease). While the reported prevalence of the sign in SBO is low (7-8%)1, the combination of SBFS and moderate to severe bowel obstruction is fairly suggestive of obstruction, particularly when associated with distal bowel collapse 7.

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

The small bowel faeces sign is most often present in distal small intestine loops, seen at a length of 4-200 cm. 

The small-bowel faeces 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 faeces 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, 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 SBFS might urge you to:

  • look for possible bowel dilatation and/or distal collapse 6-7
  • distinguish it from phytobezoar (rare), using lung windows and length measures. features in favour of a phytobezoar include 4-5:
    • higher grade of obstruction
    • absence of hazy mesentery and interloop ascites
    • length below ~10 cm
    • mean attenuation below ~-12 HU
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Article information

rID: 12363
Section: Signs
Synonyms or Alternate Spellings:
  • small-bowel faeces sign
  • Small-bowel feces sign
  • SBFS

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    Case 6: in sigmoid colocolic intussusception
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