The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall.
Bowel has 5 layers, comprised of alternating hyperechoic and hypoechoic layers. Anatomically these layers are as follows (innermost to outermost) 1,2:
- superficial mucosa: echogenic
- muscularis mucosa: hypoechoic
- submucosa: echogenic * this is the thickest layer 1
- muscularis propria: hypoechoic
- serosa: echogenic
The gut signature can be used to differentiate benign conditions, where gut signature is preserved and long segments of bowel are involved from malignant conditions where there is destruction of gut signature usually short segments of bowel2.
It can also be used to identify the appendix, enteric duplication cysts, or differentiate bowel from intra-abdominal fluid collections.
An intussusception can demonstrate prominent bowel walls on ultrasound, but the configuration is different than the normal five layers of bowel: