Objective: The aim of this study was to assess the optimum method of bowel preparation for flexible sigmoidoscopy.
Methods: A total of 164 adults undergoing flexible sigmoidoscopy at an ambulatory clinic were randomized to receive one of three preparations: a single hyperphosphate enema 1 h before the procedure; a hyperphosphate enema given 1 and 2 h before the procedure; or a hyperphosphate enema administered 1 and 2 h before the procedure, preceded by a 296 ml bottle of magnesium citrate taken p.o. the night before. Patients completed surveys on preparation and procedure comfort and satisfaction. The performing endoscopist assessed preparation quality, procedure duration, and depth of sigmoidoscope insertion.
Results: All three preparations were equally well tolerated with slightly more diarrhea reported among patients receiving magnesium citrate (p = 0.007). The addition of magnesium citrate resulted in more procedures rated by the endoscopist as excellent or good (RR 1.5, 95% CI: 1.3-1.9), deeper sigmoidoscope insertion (56 vs 51 cm, p = 0.0036), fewer procedures requiring repeat preparation (RR: 0.21, 95% CI: 0.04-0.98) and more procedures rated by patients as discomfort free (RR: 2.2, 95% CI: 1.39-3.60). Excellent and good preparations were associated with shorter procedure duration (19 vs 14 min, p = 0.008) and greater depth of insertion (56 vs 50 cm, p = 0.003). Fewer diverticuli were noted with a single enema than the two enema preparation (p = 0.006) with the remaining outcomes equal between these two groups.
Conclusion: The addition of bottle of magnesium citrate to a 2-hyperphosphate enema preparation is well tolerated and improves bowel preparation for flexible sigmoidoscopy.