# Gastritis

Manage suspected gastritis by separating histologically confirmed inflammation from reactive gastropathy, identifying Helicobacter pylori, medication or alcohol injury, and recognizing atrophic or autoimmune patterns that require systematic biopsy staging and cancer-risk surveillance planning.

**Clinical question:** How should clinicians evaluate gastritis, identify its cause, and recognize atrophic disease requiring biopsy-based risk stratification?

Updated: 2026-09-16T00:59:47.526613+00:00

## What matters in practice
- Reserve the diagnosis of gastritis for histologic gastric mucosal inflammation; lesions with minimal or absent inflammation are gastropathy and should redirect the etiologic assessment. [1][2]
- Test for active H. pylori infection with urea breath or stool antigen testing when endoscopy is not otherwise required; both can be falsely negative with acid suppression or recent antibiotic exposure. [8][9]
- In suspected atrophic gastritis or intestinal metaplasia, obtain at least five systematic biopsies from antrum/incisura and corpus in separately labeled containers, plus targeted biopsies of visible abnormalities. [11]
- H. pylori-associated gastritis is an infectious cause of chronic active gastritis; eradication heals inflammation and is essential in atrophic gastritis management. [4][11]
- Autoimmune gastritis is a corpus-predominant oxyntic process; assess for concomitant autoimmune thyroid disease and use endoscopic and histologic staging to determine surveillance needs. [10][11]

## Separate true gastritis from reactive mucosal injury

The diagnostic endpoint is cause-specific histology, not a symptom label.

Use “gastritis” when gastric biopsy shows mucosal inflammation. Apply “gastropathy” to erosive or hemorrhagic-appearing injury with minimal or no inflammation; this distinction matters because reactive injury shifts attention toward NSAIDs, alcohol, bile reflux, ischemic stress, and other chemical or hemodynamic exposures rather than infection or autoimmunity. [1][2][10]

In an acute-care presentation, identify patients in whom mucosal injury may reflect stress-related ischemia rather than uncomplicated dyspepsia. Stress is a recognized cause of gastritis secondary to mucosal ischemia; pursue the underlying hemodynamic or critical-illness driver while arranging upper endoscopy when diagnostic or therapeutic evaluation is otherwise indicated. [1][2]

At the first evaluation, document current and recent NSAID exposure, alcohol use, prior H. pylori testing or treatment, antibiotics, proton-pump inhibitor use, and autoimmune history. H. pylori, NSAIDs, and alcohol are common causes; autoimmune gastritis and stress-associated mucosal ischemia are important alternative branches. [1][2]
- Do not use endoscopic appearance alone to exclude atrophic gastritis: microscopic evaluation of gastric biopsies is required. [10]
- Consider rare bacterial phlegmonous gastritis when the presentation suggests an invasive gastric infection rather than routine chronic gastritis. [2]

*Etiologic branches that change the diagnostic next step. [1][2][4][10][11]*

| Pattern or exposure | Most useful discriminator | Next action |
| --- | --- | --- |
| H. pylori-associated gastritis | Active-infection testing or organism detection on endoscopic sampling; infection causes chronic active gastritis. [4][9] | Treat confirmed infection and document eradication with an active-infection test. [4][9] |
| NSAID-, alcohol-, bile-, or other reactive injury | Exposure history plus biopsy showing minimal inflammation supports gastropathy rather than true gastritis. [1][2][10] | Remove or modify the offending exposure and reassess the need for endoscopy or biopsy if symptoms or lesions persist. [1][2] |
| Atrophic gastritis or intestinal metaplasia | Systematic biopsies establish histologic diagnosis, distribution, and stage. [10][11] | Test for H. pylori, eradicate if present, and use endoscopic and histologic staging for surveillance decisions. [11] |
| Autoimmune gastritis | Diffuse fundic/corpus atrophy from immune-mediated oxyntic epithelial destruction. [10] | Stage endoscopically and histologically; assess for associated autoimmune thyroid disease. [11] |

## Test for active Helicobacter pylori infection correctly

Choose a test that answers whether active infection is present.

When endoscopy is not otherwise necessary, use a urea breath test or stool antigen test to diagnose active H. pylori infection. Stool antigen detection represents active infection and can be used both for initial diagnosis and confirmation of successful eradication; urea breath testing likewise documents active infection. [9]

Before a negative urea breath or stool antigen result is accepted, review medication timing. Both tests have reduced sensitivity during acid-reduction therapy and after recent antibiotics; proton-pump inhibitor use within 2 weeks can interfere with urea breath testing. Bismuth can also complicate stool antigen testing. [8][9]

Do not use IgG serology to establish cure because it cannot distinguish current infection from prior exposure. Serology may retain sensitivity despite proton-pump inhibitor or antibiotic use, but assay performance varies by kit and patient factors, so a positive result requires clinical context and does not itself establish active infection. [8]

If upper endoscopy is being performed for another indication, obtain gastric biopsies for histologic assessment and H. pylori evaluation. Histology is described as the diagnostic reference standard, but organism distribution can be patchy and noninvasive testing can be discordant with biopsy findings. [8][9]
- Use stool antigen or urea breath testing to confirm eradication because each identifies active infection. [9]
- Interpret a negative breath or stool test cautiously after proton-pump inhibitor therapy, antibiotics, bismuth exposure, or during peptic-ulcer bleeding. [8][9]
- In adults with immune thrombocytopenia, consider H. pylori screening if eradication would be offered after a positive test; platelet responses have been reported, particularly in higher-prevalence settings. [4]

*H. pylori test selection and major interpretation pitfalls. [8][9]*

| Test | What a positive result supports | Key limitation |
| --- | --- | --- |
| 13C or 14C urea breath test | Active urease-producing H. pylori infection. [9] | Proton-pump inhibitor use within 2 weeks may interfere; recent antibiotics reduce sensitivity. [8][9] |
| Monoclonal stool antigen test | Active H. pylori infection and, after treatment, eradication. [9] | Results can be complicated by proton-pump inhibitors, bismuth, antibiotics, and peptic-ulcer bleeding. [9] |
| H. pylori IgG serology | Exposure to H. pylori; it may be sensitive despite acid suppression or antibiotics. [8] | Cannot distinguish active infection from past exposure; kit performance requires local validation. [8] |
| Endoscopic biopsy histology | Gastritis phenotype and possible organism detection. [9][10] | Sampling is necessary because endoscopy without biopsy cannot diagnose or exclude atrophic gastritis. [10] |

## Use systematic biopsies when atrophy or metaplasia is suspected

Map disease distribution rather than relying on a single targeted specimen.

Perform high-quality upper endoscopy when clinical evaluation requires mucosal diagnosis, when atrophy or intestinal metaplasia is suspected, or when visible lesions need characterization. For premalignant and malignant lesion detection, use high-definition white-light endoscopy with image enhancement, mucosal cleansing, adequate insufflation, deliberate visual inspection, and photodocumentation. [11]

For suspected gastric atrophy with or without intestinal metaplasia, obtain biopsies according to a systematic protocol such as the updated Sydney System. Obtain at least five samples, place antrum/incisura and corpus specimens in separately labeled jars, and separately biopsy every suspicious focal area. This permits histologic confirmation and staging rather than simply reporting nonspecific chronic gastritis. [11]

Use anatomic distribution to direct the differential. Diffuse fundic atrophy favors autoimmune gastritis due to immune-mediated destruction of oxyntic epithelium, whereas multifocal atrophic disease is a distinct entity and H. pylori is a major cause of chronic atrophic gastritis and intestinal metaplasia. [10][18]
- Record whether atrophy and intestinal metaplasia are confined to the antrum/incisura, involve the corpus, or are multifocal; distribution is integral to etiologic classification and risk stratification. [10][11]
- Do not substitute serum pepsinogen or gastrin for biopsy-based diagnosis in an individual patient when atrophic gastritis is suspected; these markers may assist population screening, but microscopic biopsy evaluation establishes the diagnosis. [10]

### What pathology changes immediately

Chronic active gastritis with H. pylori directs eradication therapy and subsequent confirmation of active-infection clearance. Cure heals H. pylori-associated gastric inflammation. [4]

Atrophic gastritis or intestinal metaplasia requires H. pylori assessment and eradication when infection is identified. Endoscopic and histologic staging then determine whether ongoing surveillance is indicated and inform its interval. [11]
- Biopsy a visible abnormality separately from mapping biopsies so focal pathology is not obscured by background staging specimens. [11]

## Stage atrophic gastritis and identify autoimmune disease

Atrophy changes the objective from symptom attribution to cancer-risk and deficiency-risk management.

Treat atrophic gastritis as a histologic diagnosis requiring endoscopic and pathologic staging. Atrophic gastritis is a precursor state in the pathway to gastric cancer, and H. pylori-associated chronic inflammation may progress through atrophy and intestinal metaplasia. [10][18][20]

Test all patients with atrophic gastritis for H. pylori and eradicate documented infection. Eradication is an essential component of management and an adjunct to endoscopic screening and surveillance for gastric-cancer prevention; eradication has also been associated with modification of the natural course of atrophic gastritis and intestinal metaplasia. [6][11]

When biopsies show corpus/fundus-predominant atrophy suggesting autoimmune gastritis, actively evaluate the patient for concomitant autoimmune thyroid disease because this association is common. Maintain H. pylori assessment as a separate branch rather than assuming autoimmune histology excludes infection. [10][11]

Use surveillance selectively after staging rather than applying one interval to every patient with gastritis. The appropriate decision and interval depend on endoscopic and histologic risk stratification, including the extent and severity of atrophy or intestinal metaplasia and any focal lesions identified at high-quality endoscopy. [11]
- Consider opportunistic H. pylori screening in persons at increased gastric-cancer risk and consider testing adult household members of an individual with H. pylori infection. [11]
- Do not label persistent dyspepsia as true functional dyspepsia until H. pylori gastritis has been excluded or successful eradication has been confirmed. [4]

## Match treatment and follow-up to the etiologic branch

Management is exposure removal, infection cure, or surveillance-directed care—not empiric labeling alone.

For confirmed H. pylori gastritis, prescribe an eradication regimen consistent with the current H. pylori treatment guideline, then document cure using a stool antigen or urea breath test rather than serology. The cited evidence establishes active-infection testing and the need for eradication, but regimen selection should account for current guideline recommendations, prior antibiotic exposure, and local resistance patterns. [1][4][9]

For NSAID- or alcohol-associated injury, the immediate intervention is removal or modification of the causative exposure. If biopsies show little inflammation, classify the lesion as gastropathy rather than H. pylori or autoimmune gastritis and avoid treating a histologic inflammatory diagnosis that is not present. [1][2][10]

For H. pylori-negative atrophic disease, complete the systematic biopsy assessment before assigning autoimmune gastritis or another atrophic subtype. Corpus-predominant oxyntic atrophy supports autoimmune disease; multifocal atrophy requires risk stratification and surveillance planning based on endoscopic and histologic stage. [10][11]

Escalate from noninvasive testing to endoscopy when mucosal staging, lesion-directed biopsy, or evaluation for premalignant or malignant pathology is needed. Once atrophy or metaplasia is found, high-quality endoscopy with mapping biopsies is the decision-enabling procedure. [11]
- After H. pylori treatment: use stool antigen or urea breath testing to verify active-infection clearance. [9]
- After identification of atrophy or intestinal metaplasia: use endoscopic and histologic staging to determine whether surveillance is warranted and at what interval. [11]
- After autoimmune gastritis is suspected: assess for autoimmune thyroid disease. [11]

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.