Comparison of two schedules (previous evening versus same morning) of bowel preparation for colonoscopy

Evening preparation for colonoscopy is often unsatisfactory and inconvenient. We performed this study to compare the efficacy of bowel preparation at two different timings: previous evening and same morning and to compare the loss of working hours and sleep between these groups.

In this prospective, investigator blinded, randomized trial, 201 patients were enrolled from February to June 2005. Patients aged between 18 to 80 years needing colonoscopy were included. Patients with prior bowel surgery, suspected bowel obstruction or contraindications to phosphate preparation were excluded. Patients received a phosphate based preparation on the previous evening or morning of the procedure. The endoscopist and an observer scored bowel preparation using the Ottawa and Aronchick scales. Using the Ottawa scale right, middle and left colon were separately assessed. Loss of sleep and working hours were noted.

One hundred and two patients received morning preparation and 99 patients received preparation on the previous evening. There was no significant difference in bowel preparation in both the groups using the Ottawa ( P = 0.87) or Aronchick ( P = 0.22) scales. Bowel preparation for right colon was significantly better in the morning group ( P = 0.008). More working hours were lost in the evening group (7.99 vs 10.17, P< 0.001). Sleep was disturbed in 15 patients in morning group and in 42 patients in evening group ( P< 0.001).

Both preparations had similar efficacy. Right side preparation was significantly better in the morning group. Evening preparation was associated with loss of more working hours and sleep.