Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 28, 2016; 22(4): 1639-1649
Published online Jan 28, 2016. doi: 10.3748/wjg.v22.i4.1639
Diagnosing gastrointestinal illnesses using fecal headspace volatile organic compounds
Daniel K Chan, Cadman L Leggett, Kenneth K Wang
Daniel K Chan, Cadman L Leggett, Kenneth K Wang, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States
Author contributions: All authors contributed equally to this paper with the conception and design of the study, literature review, analysis, drafting, critical revision, and approval of the final version.
Supported by National Institute of Health Grants, No. P30 CA015083, No. U01 CA182940, No. U54 CA163004; and Kathy and Russ Van Cleve Endowment for Gastroenterology Research (all to Wang KK).
Conflict-of-interest statement: The eNose Company (Zutphen, NL) provided Aeonose and Aetholab equipment for research use not directly related to this study. No commercial financial support was provided. Daniel Chan and Cadman Leggett have no disclosures.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Correspondence to: Kenneth K Wang, MD, Division of Gastroenterology and Hepatology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, United States.
Telephone: +1-507-2842174 Fax: +1-507-2557612
Received: August 8, 2015
Peer-review started: August 10, 2015
First decision: September 29, 2015
Revised: October 11, 2015
Accepted: November 13, 2015
Article in press: November 13, 2015
Published online: January 28, 2016

Volatile organic compounds (VOCs) emitted from stool are the components of the smell of stool representing the end products of microbial activity and metabolism that can be used to diagnose disease. Despite the abundance of hydrogen, carbon dioxide, and methane that have already been identified in human flatus, the small portion of trace gases making up the VOCs emitted from stool include organic acids, alcohols, esters, heterocyclic compounds, aldehydes, ketones, and alkanes, among others. These are the gases that vary among individuals in sickness and in health, in dietary changes, and in gut microbial activity. Electronic nose devices are analytical and pattern recognition platforms that can utilize mass spectrometry or electrochemical sensors to detect these VOCs in gas samples. When paired with machine-learning and pattern recognition algorithms, this can identify patterns of VOCs, and thus patterns of smell, that can be used to identify disease states. In this review, we provide a clinical background of VOC identification, electronic nose development, and review gastroenterology applications toward diagnosing disease by the volatile headspace analysis of stool.

Keywords: Electronic nose, Volatile organic compounds, Feces, Mass spectrometry, Odors

Core tip: Electronic noses, which include analytical spectrometric platforms and pattern recognition devices, can be used to diagnose disease by analysis of volatile organic compounds generated by the microbiome and the end products of metabolism in the fecal headspace gas.