Update on preparation for colonoscopy.

Colonoscopy requires adequate bowel cleansing to be safe and effective. Current options for preparation include dietary restrictions plus cathartics and purgatives, large-volume gut lavage solutions, and sodium phosphate preparations. Gut lavage with or without a stimulant laxative is safe and effective, and traditionally is taken the evening before the procedure. Sodium phosphate formulations also provide effective cleansing, but fluid and electrolyte disturbances can occur. Recent advances include split administration of gut lavage solutions-ingesting only half of the solution the evening prior to, and the rest the morning of, the procedure. Split administration can yield adequate preparations in inpatients, traditionally a difficult group for proper cleansing. A new oral sulfate solution, when commercially available, should provide safe, effective cleaning with a lower ingested volume. This review discusses the current clinical experience of available preparation options and the efforts to make preparation for colonoscopy more tolerable.