A Randomized Prospective Trial Comparing Split Dose Polyethylene Glycol-Based Lavage With Clear Fluids Versus Split Dose Polyethylene Glycol-Based Lavage With a Low-Residue Diet in Preparation of Patients for Colonoscopy.

All patients between the ages 18-74 years referred to the Forzani MacPhail Colon Cancer Screening Centre (CCSC) in Calgary, Alberta, Canada for colonoscopy will be considered for inclusion. During pre-assessments at the clinic, patients are asked to consider a general research consent. If they agree to that, then they will be approached for consideration of participating in this study and presented with an "Invitation to Participate in a Research Study" form ; the study assistant will obtain final consent if they agree. Those not interested in participating will simply receive their physician's standard bowel preparation protocol. There will be no coercion of any sort. Enrollment of participants will be performed with block randomizations of 2, 4, 6 and 8 by using a computer-generated table, with allocation concealment maintained through the use of consecutively numbered sealed envelopes. Colonoscopists and investigators will be blinded to allocation groups. Patients will be allocated to one of two groups: (1) Split dose Polyethylene Glycol Based Lavage (2L + 2L) with Standard dietary instructions- a low fibre diet for 4 days prior to colonoscopy and clear fluids after a low-fibre breakfast on the day before procedure; (2) Split dose Polyethylene Glycol Based Lavage (2L + 2L) with Low Fibre Lunch dietary instructions- a low fibre diet for 4 days prior to colonoscopy and clear fluids after a low-fibre breakfast and low-fibre lunch on the day before procedure

A study assistant will assign patients to their group based on the Randomization and instruct them on the proper use of their assigned bowel preparation method. Patients will be given a tolerability questionnaire, which has been modified from a previously used questionnaire, to be completed once their bowel preparation is finished and before coming to the CCSC for the colonoscopy (included in the appendix). Patient concerns or questions regarding the preparation will be directed toward the study assistant or clinic nurses as opposed to their endoscopist, so as to avoid un-blinding the Colonoscopist. The physician performing the procedure will then complete an Ottawa Bowel Preparation Scale, a validated Simplified Bowel Preparation scale and a New Bowel Prep Scale to assess colon cleanliness.