To evaluate the efficacy and safety of different oral methods of Magnesium sulfate solution for bowel preparation before colonoscopy in elderly patients and its influence on blood electrolytes.

A total of 564 elderly patients undergoing colonoscopy in the second medical center of PLA General Hospital were randomly divided into two groups: magnesium sulfate solution in split dose group and in single douse group. The general information, bowel preparation, lesion detection rate, incidence of adverse reactions, satisfaction and abnormal changes of blood electrolyte were compared between the two groups.

There was no significant difference in age, gender, body mass index (BMI) between the two groups; The total score for Boston bowel preparation in the split dose group was (8.01 ± 0.67), which was better than that in the single dose group (7.35 ± 0.58), and the difference was statistically significant (P< 0.05); the detection rates of intestinal polyps and micro polyps (diameter < 0.5 cm) in the split dose group were 103/282 (36.5%) and 81/282 (28.7%), which were higher than 87/282 (30.9%) and 64/282 (22.7%) in the single dose group, the differences were statistically significant (both P< 0.05). There were 15 cases of abdominal distension, 3 cases of abdominal pain, 13 cases of nausea and 2 cases of vomiting in the split dose group, and 5 cases needed further enema due to inadequate bowel preparation. In the single dose group, 36 cases had abdominal distension, 5 cases had abdominal pain, 27 cases had nausea, 7 cases had vomiting, and 16 cases needed further enema due to inadequate bowel preparation. The satisfaction rate of bowel preparation in the split dose group was 97.9%, which was higher than that in the single group (90.4%), and the difference was statistically significant (P< 0.05). The incidence of electrolyte abnormality was lower in both groups, and there was no significant difference between the two groups (P> 0.05).

Compared with single oral administration, magnesium sulfate solution oral in split dose has better bowel preparation effect, lower incidence of adverse reactions and no significant effect on blood electrolytes, so it is suitable for elderly patient.