Small bowel may be recognised by its characteristic mural stratification, with alternating concentric circles of contrasting echogenicity. The thin, echogenic serosa (variably visualised) surrounds the prominent, hypoechoic muscularis, which in turn encircles an echogenic submucosal layer 2.
In health, the small bowel wall thickness is less than 3 mm, total diameter under 2.5 cm, with regular waves of peristalsis resulting in anteropulsion of the contents within.
Wall thickening, effacement of the characteristic mural pattern, and derangement of productive peristaltic waves are features common to many small bowel pathologies that may be recognised at the point of care 1.