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Gastroenterology Research and Practice
Volume 2017, Article ID 3914942, 9 pages
Review Article

Systematic Review: Outcomes by Duration of NPO Status prior to Colonoscopy

1Division of Gastroenterology, Veterans Affairs Medical Center, Minneapolis, MN, USA
2Department of Medicine, University of Minnesota, Minneapolis, MN, USA
3Center for Chronic Disease Outcomes Research, Veterans Affairs Medical Center, Minneapolis, MN, USA
4Division of Anesthesiology, Veterans Affairs Medical Center, Minneapolis, MN, USA

Correspondence should be addressed to Aasma Shaukat; ude.nmu@takuahs

Received 17 November 2016; Revised 19 May 2017; Accepted 5 June 2017; Published 16 July 2017

Academic Editor: Michel Kahaleh

Copyright © 2017 Aasma Shaukat et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background/Aims. Variation exists among anesthesia providers as to acceptable timing of NPO (“nothing by mouth”) for elective colonoscopy procedures. There is a need to balance optimal colonic preparation, patient convenience, and scheduling efficiency with anesthesia safety concerns. We reviewed the evidence for the relationship between NPO timing and aspiration incidence and colonoscopy rescheduling. Methods. We searched MEDLINE (1990–April 2015) for English language studies of any design and included them if at least one bowel preparation regimen was completed within 8 hours of colonoscopy. Study characteristics, patient characteristics, and outcomes were abstracted and verified by investigators. We determined risk of bias for each study and overall strength of evidence for primary and secondary outcomes. Results. We included 28 randomized controlled trials (RCTs), 2 controlled clinical trials, and 10 observational reports. Six studies reported on aspiration; none found that shorter NPO status prior to colonoscopy increased aspiration risk, though studies were not designed to assess this outcome (low strength of evidence). One RCT found fewer rescheduled procedures following split-dose preparation but NPO status was not well-documented (insufficient evidence). Conclusions. Aspiration incidence requiring hospitalization during colonoscopy with moderate or deep sedation is very low. No study found that shorter NPO status prior to colonoscopy increased aspiration risk. We did not find direct evidence of the effect of NPO status on colonoscopy rescheduling.