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World J Gastroenterol. Dec 21, 2014; 20(47): 17709-17726
Published online Dec 21, 2014. doi: 10.3748/wjg.v20.i47.17709
Achieving the best bowel preparation for colonoscopy
Adolfo Parra-Blanco, Alex Ruiz, Manuel Alvarez-Lobos, Ana Amorós, Juan Cristóbal Gana, Patricio Ibáñez, Akiko Ono, Takahiro Fujii
Adolfo Parra-Blanco, Alex Ruiz, Manuel Alvarez-Lobos, Patricio Ibáñez, Department of Gastroenterology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 833-0024, Chile
Ana Amorós, Department of Gastroenterology, Hospital Universitario de la Candelaria, 38916 Santa Cruz de Tenerife, Spain
Juan Cristóbal Gana, Gastroenterology and Nutrition Unit, Division of Pediatrics, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago 833-0024, Chile
Akiko Ono, Department of Gastroenterology, Hospital Universitario Virgen de la Arrixaca, 30001 Murcia, Spain
Takahiro Fujii, TF Clinic, Tokyo 197-0804, Japan
Author contributions: Parra-Blanco A, Ruiz A, Alvarez-Lobos M, Amorós A, Gana JC, Ibáñez P, Ono A and Fujii T wrote the paper, all the authors approved the final version.
Correspondence to: Adolfo Parra-Blanco, MD, PhD, Faculty of Medicine, Department of Gastroenterology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 367, Avda. Libertador Bernardo OHiggins 340, Santiago 833-0024, Chile.
Telephone: +56-223-543820
Received: November 25, 2013
Revised: July 20, 2014
Accepted: November 8, 2014
Published online: December 21, 2014
Processing time: 390 Days and 1.7 Hours

Bowel preparation is a core issue in colonoscopy, as it is closely related to the quality of the procedure. Patients often find that bowel preparation is the most unpleasant part of the examination. It is widely accepted that the quality of cleansing must be excellent to facilitate detecting neoplastic lesions. In spite of its importance and potential implications, until recently, bowel preparation has not been the subject of much study. The most commonly used agents are high-volume polyethylene glycol (PEG) electrolyte solution and sodium phosphate. There has been some confusion, even in published meta-analyses, regarding which of the two agents provides better cleansing. It is clear now that both PEG and sodium phosphate are effective when administered with proper timing. Consequently, the timing of administration is recognized as one of the central factors to the quality of cleansing. The bowel preparation agent should be administered, at least in part, a few hours in advance of the colonoscopy. Several low volume agents are available, and either new or modified schedules with PEG that usually improve tolerance. Certain adjuvants can also be used to reduce the volume of PEG, or to improve the efficacy of other agents. Other factors apart from the choice of agent can improve the quality of bowel cleansing. For instance, the effect of diet before colonoscopy has not been completely clarified, but an exclusively liquid diet is probably not required, and a low-fiber diet may be preferable because it improves patient satisfaction and the quality of the procedure. Some patients, such as diabetics and persons with heart or kidney disease, require modified procedures and certain precautions. Bowel preparation for pediatric patients is also reviewed here. In such cases, PEG remains the most commonly used agent. As detecting neoplasia is not the main objective with these patients, less intensive preparation may suffice. Special considerations must be made for patients with inflammatory bowel disease, including safety and diagnostic issues, so that the most adequate agent is chosen. Identifying neoplasia is one of the main objectives of colonoscopy with these patients, and the target lesions are often almost invisible with white light endoscopy. Therefore excellent quality preparation is required to find these lesions and to apply advanced methods such as chromoendoscopy. Bowel preparation for patients with lower gastrointestinal bleeding represents a challenge, and the strategies available are also reviewed here.

Keywords: Colonoscopy, Optimal preparation, Polyethylene glycol, Sodium phosphate, Special patients, Timing

Core tip: Bowel preparation for colonoscopy is a central issue related to the quality of the procedure. There are different agents for bowel preparation that can be administered with different schedules. We review the most commonly used agents, as well as new agents and combinations. Moreover, certain considerations should be taken into account for special populations in order to improve safety, efficacy and tolerance. Regimens for bowel preparation in special situations are discussed, such as for pediatric patients, patients with diabetes or inflammatory bowel disease, and in cases of heart or kidney failure or lower gastrointestinal bleeding.