DEFECATION MECHANISM IN MAN

Abstract

The present study was made to investigate the details of defecation mechanism .The subjects studied were 14 normal adults who did not suffer from intestinal diseases and 13 patients with colonic diseases who have undergone resection of the rectosigmoid.For this purpose 16 mm X-ray cinematogram was taken on every patient using barium enema in supine posture. A photo-optical measurement was performed on these cinefilms with a film motion analyzer.
The results obtained are as follows:
1. The subjects felt the urge to defecate by giving barium into the rectal ampulla .At this time enema volume of the barium averaged 196 ml.
2. The distension of the wall of the rectal ampulla by increasing the internal pressure seems to be one of the factors giving the awareness of the need to evacuate the rectum.
3. In the left side colon and rectum, obvious movement was not observed before defecation took place. The colon and rectum went down as a whole toward the pelvic space at the time when defecation started.
When distension at the ampulla by intraabdominal pressure exceeded the tension of the anal sphincter, defecation started. At the same time obvious movement was not able to be observed on the left side colon and the rectum .
4. The transportation of feces in the left side colon was observed during defecation.At the end of defecation the rectum and left side colon returned to the resting condition similar to that before defecation started . The main function of the left side colon seems to be storage of feces.
5. Good fecal continence was noticed in the cases resected the rectum at the height more than 7 cm above the anal ring.