Comparative studies on the usefulness of phosphate versus glycerin enema in preparation for colon examinations

Fifty of 100 persons who had undergone health screening received phosphate enema while the other 50 received glycerin enema prior to proctoscopy and barium enema, and their usefulness for preparation for colon examination was compared by a double-blind test. There was no significant difference in the degree of colonic cleansing achieved by proctoscopy and barium enema. In the subjects who received phosphate enema, the incidence of abdominal pain was less than that in those who received glycerin enema, while the effect of phosphate enema on defecation appeared later than that of glycerin enema, indicating prolonged stool retention in the subjects given phosphate enema. To study the safety of the two enemas, either phosphate enema, glycerin enema or physiological saline solution as a control was administered at 0.35 ml/animal in the rectum by 4-h closure of the anus in 10 male 7-week-old Wistar rats, and the rectal mucosa was observed for irritation macroscopically and histopathologically. Glycerin enema produced less irritation than phosphate enema diffusely in the entire area of the rectum, while phosphate enema produced more local irritation at the end of the rectum than glycerin enema. The differences in the extent of irritation and injury between phosphate and glycerin enemas were considered to be derived from differences in the pharmacologic actions of these drugs. If the extent of injury were included in the extent of irritation, the difference in irritation between phosphate and glycerin enemas would not be significant. As described above, no specific difference seem to exist in the usefulness of phosphate and glycerin enemas as preparation for colon examination.