Utility of gastrointestinal ultrasound in functional gastrointestinal disorders: A narrative review

Gastrointestinal(GI) ultrasound(GIUS) is valuable in the evaluation of GI diseases such as inflammatory bowel disease, but its use in functional GI disorders(FGIDs) is largely unknown although promising. In order to review the current knowledge on current and potential uses of GIUS in FGIDs, information was obtained via a structured literature search through Pub Med, EMBASE and Google Scholar databases with a combination of MESH and keyword search terms: "ultrasound", "functional GI disorders", "irritable bowel syndrome","functional dyspepsia", "intestinal ultrasound", "point of care ultrasonography","transabdominal sonography", "motility", "faecal loading", "constipation". GIUS is currently used for various settings involving upper and lower GI tracts,including excluding organic diseases, evaluating physiology, guiding treatment options and building rapport with patients. GIUS can be potentially used to correlate mechanisms with symptoms, evaluate mechanisms behind treatment efficacy, and investigate further the origin of symptoms in real-time. In conclusion, GIUS is unique in its real-time, interactive and non-invasive nature,with the ability of evaluating several physiological mechanisms with one test,thus making it attractive in the evaluation and management of FGIDs. However,there are still limitations and concerns of operator dependence and lack of validation data for widespread implementation of GIUS in FGIDs.