SCINTIGRAPHIC ASSESSMENT OF COLONIC FUNCTION DURING DEFECATION

The aim of this study was to develop a method by which rectal and colo nic activity could be examined during defaecation under physiological conditions, in order to evaluate whether the colon plays a role in def aecation. Subjects presented to the Nuclear Medicine department on the day following ingestion of oral In-111 labelled DTPA, when they devel oped the normal urge to defaecate. Defaecation took place in a private room while dynamic scintigraphy of the rectum and colon was recorded. Fourteen subjects were studied (8 normal subjects, 4 with constipatio n, 2 with irritable bowel syndrome). In 13 subjects the left colon was visualized during defaecation and emptying was clearly observed in 12 . The right colon was visualised in 11 subjects and emptying was seen in 7. Mean percentage segmental evacuation was right colon 20%, left c olon 32% and rectum 66%. Colonic emptying occurs during defaecation, w hich is not a process of rectal evacuation only. This has implications for the understanding of the pathophysiology of obstructed defaecatio n.