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Comb sign

AbdomenCT

Engorged, dilated vasa recta stand out perpendicular to an inflamed bowel loop like the teeth of a comb.

What it means

Active mesenteric hyperaemia adjacent to actively inflamed bowel.

Mechanism

Transmural inflammation increases blood flow, engorging and separating the vasa recta so they line up like comb teeth.

Associated conditions

  • Crohn disease (active)
  • Other active inflammatory bowel disease
  • Mesenteric inflammation
  • Infectious enteritis

Pearls

  • The comb sign is a marker of disease activity in Crohn disease.
  • It is often accompanied by mural hyperenhancement and fibrofatty proliferation.

References

  • Radiopaedia: Comb sign (Crohn disease)

For educational use only. This dictionary is a study aid and reference, not a diagnostic tool, and must not be used to guide clinical decisions or patient care. Imaging appearances vary; always correlate with the full clinical picture and confirm with a qualified radiologist.