Functional Diagnosis

A simple technique for measuring gastrointestinal transit times using radioopaque pellets of barium-impregnated polythene has been developed and validated. A normal range has been established by studying 25 normal subjects; all passed the first marker within three days and most passed 80% of the markers within five days.

The function of the anal sphincters has been studied by obtaining continuous recordings of the pressure in the anal canal and the electromyographic activity in the striated sphincter muscles during expansion of the ampulla recti by means of an air balloon. Ten healthy subjects were examined before and after the striated muscles had been entirely paralysed by bilateral pudendal block, making it possible to record the activity from the internal sphincter alone. The results show that the internal sphincter contributes about 85% of the pressure in the anal canal at rest but only about 40% after a sudden substantial distension of the rectum. During constant substantial rectal distension, the internal sphincter accounts for about 65% of the anal pressure. It is concluded that the internal sphincter in the adult is chiefly responsible for anal continence at rest. In the event of sudden substantial distension of the rectum, continence is maintained by the striated sphincter muscles, whereas both sphincter systems probably have an important function during constant distension of the rectum.