What is the endoscopic definition of BO and how is it described?
Barrett’s Oesophagus (BO) is a premalignant condition of the oesophagus defined as the presence of metaplastic columnar epithelium,which endoscopically appears as salmon pink mucosa, extending above the gastro-oesophageal junction (GOJ) and into the tubular oesophagus, thereby replacing the stratified squamous epithelium that normally lines the distal oesophagus.
The columnar type mucosa can be one of three types: gastric-fundic type, cardiac type and intestinal-type. It is the intestinal type that has been clearly shown to predispose to cancer development and therefore most experts agree that an oesophageal biopsy of columnar epithelium above the GOJ showing intestinal type is required to confirm and establish a diagnosis of BO, rather than relying on endoscopy alone. This is discussed in more detail in the section titled What is the histological definition of BO?
Intestinal metaplasia at the cardia
There has been debate in the literature as to whether or not cardiac-type epithelium should be included in the definition of BO. Hence according to the 2011 American Gastroenterological Association (AGA) Technical Review on the Management of Barrett’s Oesophagus “’Barrett’s esophagus’ presently should be used only for patients who have intestinal metaplasia in the esophagus”. This differs from the definition in previous British Society of Gastroenterology in which BO was defined as “an endoscopically apparent area above the oesophagogastric junction that is suggestive of Barrett’s, which is supported by the finding of columnar lined oesophagus on histology.” This was based on the premise that the diagnosis of IM can be limited by sampling error in mucosal biopsies, especially were less than 8 biopsies were taken. More recently the BSG guidelines have been updated, and although admitting that 'barrett's mucosa' without IM has a lower risk of progression to cancer based on the population-based study from the Northen Ireland register, they still recommend that "the presence of IM is not a prerequisite for the definition of Barrett’s oesophagus", and if cardiac type epithelium were present in two subsequent endoscopies in segments <=3cm, these patients can be discharged from further surveillance.
This issue of length of columnar segment with IM and surveillance is discussed in later chapters on recommended surveillance for patients with BO (see also How frequently should patients with BO undergo endoscopy?), however for the purposes of these guidelines, given the population-based study from the Northen Ireland register showning a significantly lower risk of progression to cancer in those patients without intestinal-type epithelium we advocate utilisation of the AGA definition provided that appropriate sampling of the columnnar segment has been performed.
Endoscopic landmarks for a diagnosis of BO
A reliable endoscopic diagnosis of BO depends on the accurate endoscopic recognition of the anatomic landmarks at the GOJ and squamocolumnar junction (SCJ). To standardise the objective diagnosis of endoscopic BO, the Prague C & M Criteria were proposed by a subgroup of the International Working Group for the Classification of Oesophagitis (IWGCO). In this system, the landmark for the GOJ is the proximal end of the gastric folds. Whilst the exact definition of what constitutes the GOJ remains unresolved with no universally accepted definition, the vast majority of published papers on BO have used the proximal extent of the gastric folds, which was first described in 1987 by McClave et.al., and indeed the Prague C & M Criteria have been widely adopted. In the original paper, criteria were externally validated by 29 expert endoscopists and the interobserver agreement, for recognising different lengths of BO and the GOJ location position were very good. This has recently been further externally validated by another group where 16 gastroenterology trainees had similary high interobserver agreement confirming the utility of these criteria by both trainees and experts after adequate training. However recognition of ≤ 1 cm of BO using the Prague C & M Criteria was less reliable, which is the basis for the recommendation of recent BSG guidelines to "suggest that 1 cm (M of Prague criteria) should be the minimum length for an endoscopic diagnosis of Barrett’s (Evidence grade IV)".
In addition, a recent study in Japan has also highlighted the importance of training on Prague criteria. Before adequate training interobserver agreement amongst a group of 25 experienced endoscopists for identification of the GOJ was poor but this improved markedly after training. It should also be noted that a criticism of the Prague criteria are that they may fail to identify short segment BO, a lesion found frequently in most Asian countries. Hence, many Japanese authors believe endoscopic BO is better defined as the most distal extent of the palisade vessels. Given the absence of evidence to advocate the use of one over the other, and the widespread use of Praque C & M Criteria by western endoscopists, we advocate the use of the proximal extent of the gastric folds in defining BO.
The proximal margin of BO in the Prague Criteria are based on measurement of both the circumferential (C) and maximal (M) extent of metaplasia (shown in figures 1 & 2 below). There is less debate regarding this margin and it is defined as maximum extent of columnar epithelium above the GOJ.
Figure 1. Diagrammatic representation of endoscopic Barrett’s Oesophagus showing an area classified as C2M5. C: extent of circumferential metaplasia; M: maximal extent of the metaplasia (C plus a distal “tongue” of 3 cm); GEJ: gastroesophageal junction.
Figure 2. Video still of endoscopic Barrett’s Oesophagus showing an area classified as C2M5. C: extent of circumferential metaplasia; M: maximal extent of the metaplasia (C plus a distal “tongue” of 3 cm).
Source: Images used from Publication Gastroenterology, 131(5), Prateek Sharma, John Dent, David Armstrong et. al, The Development and Validation of an Endoscopic Grading System for Barrett’s Esophagus: The Prague C & M Criteria, p1395-1396, Copyright (2006), with permission from Elsevier
Biopsies assessing for intestinal metaplasia (columnar epithelium with goblet cells) should be performed when any length of salmon pink mucosa is seen extending above the gastro-oesophageal junction into the tubular oesophagus for a confirmed diagnosis of Barrett’s Oesophagus.
The presence of Barrett’s Oesophagus should be described using the Prague C & M Criteria.
- Vakil N, van Zanten SV, Kahrilas P, Dent J, Jones R, Global Consensus Group. The Montreal definition and classification of gastroesophageal reflux disease: a global evidence-based consensus. Am J Gastroenterol 2006 Aug;101(8):1900-20; quiz 1943 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/16928254.
- Shaheen NJ, Richter JE. Barrett's oesophagus. Lancet 2009 Mar 7;373(9666):850-61 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/19269522.
- Paull A, Trier JS, Dalton MD, Camp RC, Loeb P, Goyal RK. The histologic spectrum of Barrett's esophagus. N Engl J Med 1976 Aug 26;295(9):476-80 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/940579.
- Shaheen NJ, Crosby MA, Bozymski EM, Sandler RS. Is there publication bias in the reporting of cancer risk in Barrett's esophagus? Gastroenterology 2000 Aug;119(2):333-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/10930368.
- Spechler SJ, Sharma P, Souza RF, Inadomi JM, Shaheen NJ, American Gastroenterological Association. American Gastroenterological Association medical position statement on the management of Barrett's esophagus. Gastroenterology 2011 Mar;140(3):1084-91 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/21376940.
- Watson A, Heading RC, Shepherd NA. Guidelines for the diagnosis and management of Barrett’s columnar-lined oesophagus. BSO 2005 [cited 2013 Jan 11] Abstract available at http://www.bsg.org.uk/pdf_word_docs/Barretts_Oes.pdf.
- Fitzgerald RC, di Pietro M, Ragunath K, Ang Y, Kang JY, Watson P, et al. British Society of Gastroenterology guidelines on the diagnosis and management of Barrett's oesophagus. Gut 2014 Jan;63(1):7-42 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/24165758.
- Bhat S, Coleman HG, Yousef F, Johnston BT, McManus DT, Gavin AT, et al. Risk of malignant progression in Barrett's esophagus patients: results from a large population-based study. J Natl Cancer Inst 2011 Jul 6;103(13):1049-57 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/21680910.
- Ishimura N, Amano Y, Appelman HD, Penagini R, Tenca A, Falk GW, et al. Barrett's esophagus: endoscopic diagnosis. Ann N Y Acad Sci 2011 Sep;1232:53-75 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/21950807.
- Sharma P, Dent J, Armstrong D, Bergman JJ, Gossner L, Hoshihara Y, et al. The development and validation of an endoscopic grading system for Barrett's esophagus: the Prague C & M criteria. Gastroenterology 2006 Nov;131(5):1392-9 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17101315.
- McClave SA, Boyce HW Jr, Gottfried MR. Early diagnosis of columnar-lined esophagus: a new endoscopic diagnostic criterion. Gastrointest Endosc 1987 Dec;33(6):413-6 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/3443258.
- Vahabzadeh B, Seetharam AB, Cook MB, Wani S, Rastogi A, Bansal A, et al. Validation of the Prague C & M criteria for the endoscopic grading of Barrett's esophagus by gastroenterology trainees: a multicenter study. Gastrointest Endosc 2012 Feb;75(2):236-41 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/22248595.
- Amano Y, Ishimura N, Furuta K, Takahashi Y, Chinuki D, Mishima Y, et al. Which landmark results in a more consistent diagnosis of Barrett's esophagus, the gastric folds or the palisade vessels? Gastrointest Endosc 2006 Aug;64(2):206-11 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/16860070.
- Choi DW, Oh SN, Baek SJ, Ahn SH, Chang YJ, Jeong WS, et al. Endoscopically observed lower esophageal capillary patterns. Korean J Intern Med 2002 Dec;17(4):245-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/12647639.
- Vianna A, Hayes PC, Moscoso G, Driver M, Portmann B, Westaby D, et al. Normal venous circulation of the gastroesophageal junction. A route to understanding varices. Gastroenterology 1987 Oct;93(4):876-89 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/3623028.