Evaluation of gastric acid secretion at endoscopy with a modified Congo red test

Prevalence of achlorhydria in an Asian population detected using Congo red staining during routine gastroscopy: 22 years' experience from a single centre

OBJECTIVE

We aimed to study the prevalence of achlorhydria (AC) in a large Asian population.

DESIGN

Medical records of patients who underwent oesophagogastroduodenoscopy (OGD) with Congo red staining method at the Vichaiyut Hospital from January 2010 to December 2019 were retrospectively reviewed.

RESULTS

A total of 3597 patients was recruited; 223 were excluded due to concurrent use of proton pump inhibitors. Eighteen from 3374 patients (0.53%) had AC. Seven patients were presented with permanent AC (5F, 2M) (median age=69 years; range 58-92). Among 11 patients with temporary AC (5M, 6F: mean age 73.4 years; SD 13.2 years), all had gastrointestinal Helicobacter pylori bacterial infection and were over 45 years old. After successful treatment for H. pylori, AC was absent among patients with temporary AC. If counting only patients over 45 years of age, the prevalence of AC was 0.68% (18/2614). No adverse events arising from Congo red occurred.

CONCLUSION

AC is relatively rare. Permanent and temporary AC were found only when they were over 55 and 45 years old, respectively. Staining Congo red on gastric mucosa can be safely and routinely incorporated into the OGD procedure for early detection of AC. We recommended a low-cost screening test such as serum vitamin B levels for screening only in patients aged 50 and over.

Gastric acid secretion: changes during a century

The advances in knowledge of gastric physiology within the past century have been the most exciting and important in this area of interest for many decades. The aim of this presentation consists of a comprehensive review of the extensive recent literature on this topic in order to highlight milestones in the field of gastric physiology, in particular in gastric acid secretion, gastric pathophysiology, acid-related diseases and use of acid regulatory drugs. Moreover, in the 21st century there have been many epidemiologic changes as well as a decrease of Helicobacter pylori infection and gastric cancer together with an increase of gastroesophageal reflux disease and the related increase of pomp proton inhibitor wide use.

Autofluorescence imaging videoendoscopy in the diagnosis of chronic atrophic fundal gastritis

PURPOSE

Diagnosis of chronic atrophic fundal gastritis (CAFG) is important to understand the pathogenesis of gastric diseases and assess the risk of gastric cancer. Autofluorescence imaging videoendoscopy (AFI) may enable the detection of mucosal features not apparent by conventional white-light endoscopy. The purpose of this study was to estimate the diagnostic ability of AFI in CAFG.

METHODS

A total of 77 patients were enrolled. Images of the gastric body in AFI and white-light mode were taken to assess the extent of gastritis, and biopsies were taken from green (n = 119) and purple (n = 146) mucosa in AFI images. The diagnostic accuracy of green mucosa for CAFG was investigated according to the Sydney system.

RESULTS

In per-patient analysis, the accuracy of green mucosa in patients with activity, inflammation, atrophy and intestinal metaplasia was 64, 93, 88 and 81%, respectively. In per-biopsy analysis, the accuracy for activity, inflammation, atrophy and intestinal metaplasia was 55, 62, 76 and 76%, respectively. Green areas in the gastric body exhibited more inflammation (p < 0.001), atrophy (p < 0.001) and intestinal metaplasia (p < 0.001), whereas purple areas rarely contained atrophy or intestinal metaplasia. The kappa statistics for inter- and intra-observer agreement of AFI on assessing the extent of CAFG were 0.66 and 0.47, while those for white-light endoscopy were 0.56 and 0.39.

CONCLUSIONS

AFI could diagnose the extent of CAFG as a green area in the gastric body, with higher reproducibility compared with white-light endoscopy. Therefore, AFI may be a useful adjunct to endoscopy to identify patients at high risk of developing gastric cancer.

Chromoendoscopy

Chromoendoscopy involves the use of stains or dyes during endoscopy to improve the visualization and characterization of the gastrointestinal mucosa. Its main clinical application is the detection of dysplasia or early cancer of the gastrointestinal tract in individuals with pre-malignant conditions or hereditary and environmental factors that predispose them to cancer. The utility of chromoendoscopy has been mostly studied in squamous cell carcinoma of the esophagus, Barrett's esophagus, gastric cancer, colorectal polyps, and chronic ulcerative colitis. Although chromoendoscopy has been shown to be feasible and safe, several limitations have prevented its widespread use in endoscopy. Despite this, chromoendoscopy remains a useful adjunct to standard white light endoscopy in the visualization of mucosal lesions, which may potentially improve tissue diagnosis and impact patient care.

Sustained epithelial proliferation in a functionally irreversible fundic mucosa after Helicobacter pylori eradication

BACKGROUND

We recently reported the expansion of the acid-secreting mucosa following Helicobacter pylori eradication with Congo red chromoendoscopy for a short-term follow-up of up to 7 months. We aimed to extend the observation period and to clarify the characteristic features of acid-secreting and non-acid-secreting mucosa.

METHODS

In 24 H. pylori-positive patients with fundic atrophy, Congo red chromoendoscopy was performed prior to, 1 month, 7 months, and finally more than 2 years after the eradication. The areas of the acid-secreting mucosa were evaluated semiquantitatively. Two gastric biopsy specimens were taken from the acid-secreting and non-acid-secreting areas at the final chromoendoscopy and were subjected to histologic evaluation and immunohistochemistry for Ki-67 as a proliferation index.

RESULTS

After a gradual increase in acid-secreting areas for up to 7 months after eradication, they further increased in 79% subjects between 7 months and the final observation at a mean follow-up of 62 months. However, there still existed non-acid-secreting mucosa in the fundic area in all subjects, indicating that the expansion of acid-secreting mucosa remained partial. Compared with the neighboring acid-secreting area, the non-acid-secreting area was characterized histologically by higher degrees of residual inflammation, mucosal atrophy, and intestinal metaplasia, and by sustained hyperproliferation as well.

CONCLUSIONS

Functionally irreversible (non-acid-secreting) gastric mucosa after eradication was associated with extensive intestinal metaplasia and sustained hyperproliferation, suggesting that such mucosa still possesses malignant potential. Congo red chromoendoscopy may be useful for estimating the risk of subsequent development of gastric cancer following successful H. pylori eradication by determining the distribution of functionally irreversible mucosa.

Novel chromoendoscopic method using an acetic acid-indigocarmine mixture for diagnostic accuracy in delineating the margin of early gastric cancers

BACKGROUND AND AIM

Recent endoscopic imaging techniques for recognition of unclear lesions in the stomach (e.g. narrow band imaging, magnifying endoscopy) require special equipment and therefore are not commonly used. The aim of the present study was to estimate the accuracy of a new chromoendoscopic method using an acetic acid-indigo carmine mixture (AIM) in diagnosing early gastric cancers (EGC).

METHODS

Studied were 108 EGC lesions in 104 patients. EGC were initially observed by white light (WL) after which indigo carmine (IC) solution was sprinkled onto the gastric mucosa. Images by WL and IC observation were recorded by a digital filing system. After washing away IC solution with water, AIM solution was sprinkled onto the gastric mucosa and images were recorded. Margin lines of EGC determined by each observation were drawn on recorded images by graphic software for comparison with resected specimens. After lines were similarly drawn on images of resected specimens, the extent of the lesions was compared with that determined by endoscopic images.

RESULTS

Diagnostic accuracy of WL, IC, and AIM observations were 50.0%, 75.9% and 90.7%, respectively. No adverse events occurred with the AIM method.

CONCLUSIONS

This chromoendoscopic method can be used to delineate the margin of EGC accurately, easily, safely and inexpensively.

Regional differences in the recovery of gastric acid secretion after Helicobacter pylori eradication: evaluations with Congo red chromoendoscopy

BACKGROUND

Gastric-acid secretion is reduced in Helicobacter pylori-positive fundic atrophic gastritis, but it is restored by the eradication. However, changes in the distribution of acid-secreting mucosa after the eradication remain unknown. Congo red chromoendoscopy is capable of visualizing the acid-secreting fundic mucosa.

OBJECTIVE

To evaluate the effect of H pylori eradication on the distribution of acid-secreting mucosa in the fundus by using Congo red chromoendoscopy.

DESIGN

An assessment of the distribution of acid-secreting mucosa by the visualized images of Congo red chromoendoscopy and a histologic evaluation of biopsy specimens were performed before and 1 and 7 months after the eradication. The areas of the acid-secreting mucosa in the lesser and greater curvatures of the fundus were evaluated semiquantitatively.

PATIENTS

Thirty-seven patients positive for H pylori and with fundic atrophic gastritis.

RESULTS

The area of the acid-secreting mucosa increased in 27 cases (73%) by 1 month after eradication, and in 32 cases (86%) by 7 months. This expansion of the acid-secreting mucosa coincided with the improvement of inflammatory changes rather than with that of the mucosal atrophy and was more prominent on the greater curvature than on the lesser curvature.

CONCLUSIONS

The acid-secreting mucosa in the fundus expanded in most cases with fundic atrophic gastritis after H pylori eradication, which could be responsible for the increase in acid secretion after the treatment. Regional differences in the recovery of local acid secretion may be associated with site-specific susceptibility to the development of gastric cancer after successful eradication.

Gastric secretion

PURPOSE OF REVIEW

Gastric acid facilitates the digestion of protein and the absorption of iron, calcium, and vitamin B12. It also protects against bacterial overgrowth and enteric infection, including prion disease. When homeostatic mechanisms malfunction, the volume and concentration of acid may overwhelm mucosal defense mechanisms, leading to duodenal ulcer, gastric ulcer, and gastroesophageal reflux disease. This article reviews recent knowledge contributing to understanding of the regulation of gastric acid secretion at the central, peripheral, and intracellular levels.

RECENT FINDINGS

The vagus nerve contains afferent fibers that transmit sensory information from the stomach to the nucleus of the solitary tract. Input from the nucleus of the solitary tract is relayed to vagal efferent neurons that originate from two brain stem nuclei: the nucleus ambiguus and the dorsal motor nucleus of the vagus. The latter is also influenced by thyrotropin-releasing hormone neurons that act centrally to stimulate acid secretion. The main peripheral stimulants of acid secretion are the hormone gastrin and the paracrine amine histamine. Gastrin stimulates acid secretion directly and, more importantly, indirectly by releasing histamine from fundic enterochromaffin-like cells. Gastrin also exerts trophic effects on various tissues, including the gastric and intestinal mucosa. The main inhibitor of acid secretion is somatostatin. Somatostatin, acting via ssTR2 receptors, exerts a tonic paracrine inhibitory influence on the secretion of gastrin, histamine, and acid secretion. Calcitonin gene-related peptide, adrenomedullin, amylin, atrial natriuretic peptide, and pituitary adenylate cyclase-activating polypeptide all stimulate somatostatin secretion and thus inhibit acid secretion. HK-ATPase, the proton pump of the parietal cell, is stored within cytoplasmic tubulovesicles during the resting state, but during stimulation, it is shuttled to the canalicular membrane by a poorly understood mechanism that probably involves soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins. The proton pump inhibitor, pantoprazole, is unique in that it binds cysteine 822, located deep within the membrane domain of the alpha-subunit. The difficulty that reducing agents, such as glutathione, have in reaching cysteine 822 may be responsible for the longer half-time for acid recovery observed with pantoprazole. Hypergastrinemia, induced by proton pump inhibitors, enhances expression of cyclooxygenase-2 and hence prostaglandins within parietal cells, a feedback pathway that may protect the stomach against acid-induced damage.

SUMMARY

In the past year, significant advances have been made in understanding of the regulation of gastric acid secretion. Ultimately, these advances should lead to improved therapies to prevent and treat acid-related disorders. Gastric acid secretion must be precisely controlled at a variety of levels to prevent disease caused by hyperchlorhydria and hypochlorhydria. The mechanisms include neural (central and peripheral), hormonal, paracrine, and intracellular pathways that operate in concert to switch acid secretion on during ingestion of a meal and off during the interdigestive period. A better understanding of the physiology of acid secretion in health and disease should eventually lead to improved therapies to prevent and treat acid-related disorders.