Upper gastrointestinal (GI) symptoms include
Some upper GI symptoms represent disorders of gut-brain interaction (also called functional gastrointestinal illness; ie, no physiologic cause can be found after extensive evaluation).
Lower GI symptoms include
As with upper GI symptoms, lower GI symptoms result from physiologic illness or represent a functional disorder such as irritable bowel syndrome (ie, no radiologic, biochemical, or pathologic abnormalities are found even after extensive evaluation). The reasons for functional symptoms are not clear. Evidence suggests that patients with functional symptoms may have disturbances of motility, nociception, or both; ie, they perceive as uncomfortable certain sensations (eg, luminal distention, peristalsis) that other people do not find distressing.
