Electromyography and manometry of the pelvic colon--a contribution to the understanding of its function.

OBJECTIVE

To study the adaptation of the rectum to pressure waves in the sigmoid and the motility response to the administration of a bile salt microenema.

DESIGN

Electrical and motor activity was studied in 20 men and 20 women during a 2-h fast and for 2 h after a 1000-kcal meal, and also after a bile salt microenema.

METHODS

An intraluminal probe with three sets of two electrodes and one miniballoon was used for simultaneous EMG and manometry recording.

RESULTS

Four types of spike bursts were observed: (1) migrating long spike bursts that initiated propagating pressure waves on 99% of occasions; (2) non-migrating long spike bursts that did not originate pressure waves; (3) rhythmic short spike bursts that were also not related to pressure waves; and (4) rhythmic long spike bursts that originated rhythmic segmental pressure waves frequently brought up by a migrating long spike burst. The meal significantly increased the duration of activity of the migrating long spike bursts in the sigmoid colon (from 16.8% before the meal to 21.8% after it, P < 0.05) and the motility index, P < 0.05, both of them in two peaks. A rectosigmoidal pressure gradient was shown. The bile salt microenema produced a desire to defecate and increased motility in only half of the cases.

CONCLUSION

The rectosigmoidal pressure gradient was due to: (1) higher-amplitude pressure waves in the sigmoid colon than in the other two sites, and (2) propagating relaxation waves in the rectum and in the rectosigmoid junction.