A study of the genesis of colic.

To investigate local events in the gut as well as the location and duration of discomfort associated with colic, mild phasic pain was induced by balloon distension and bolus injection of normal saline at various sites in the gut of 1 normal volunteer and 12 patients with gut disorders. Intraluminal pressures were recorded. Pain was experienced only when a rise in baseline pressure occurred in a segment of gut at least 6 cm and up to 32 cm long. Painful segmental pressure rises were often low compared with non-painful localised pressure rises. Induced phasic pain had all the characteristics of colic, usually lasted less than a minute in both small and large intestine, and while frequently beginning paracentrally, tended to spread across the midline with increasing severity.