Gastritis

Overview

•Epigastric pain - burning/gnawing, often postprandial

•Nausea and vomiting, bloating, early satiety, belching

•Haematemesis or melaena - indicates mucosal bleeding

•Many patients (especially H. pylori) are entirely asymptomatic

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ALARM symptoms requiring urgent OGD: Anaemia (iron deficiency), Loss of weight, Anorexia, Recent/rapid onset symptoms, Melaena or haematemesis, Swallowing difficulty (dysphagia). Also urgent OGD: age ≥55 with new dyspepsia + weight loss/upper abdominal pain/reflux, or new dysphagia at any age.

Investigations

•First-line (non-invasive H. pylori testing): carbon-13 urea breath test - stop PPIs 2 weeks and antibiotics 4 weeks before to avoid false negatives

•Alternative non-invasive: stool H. pylori antigen test - also used to confirm eradication

•H. pylori serology (IgG) - cannot distinguish active from past infection; not recommended to confirm eradication

•FBC - iron deficiency anaemia (chronic bleeding) or macrocytic anaemia (B12 deficiency in autoimmune gastritis)

•Gold standard - OGD with biopsy - direct visualisation; CLO (rapid urease) test on biopsy confirms H. pylori; histology assesses severity, metaplasia, dysplasia, malignancy. Indicated for ALARM symptoms, age ≥55 with new dyspepsia, or failed empirical treatment

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Serology cannot confirm eradication - antibodies persist after successful treatment. Only the urea breath test or stool antigen test are recommended for post-treatment confirmation, at least 4 weeks after antibiotics and 2 weeks after stopping the PPI.

Management

•Lifestyle (all patients): reduce/stop alcohol, stop smoking, avoid NSAIDs/aspirin, smaller and more frequent meals

•First-line (H. pylori positive) - triple therapy for 7 days: omeprazole 20 mg twice daily + clarithromycin 500 mg twice daily + amoxicillin 1 g twice daily

•If penicillin-allergic: replace amoxicillin with metronidazole 400 mg twice daily - patient must abstain from alcohol (disulfiram-like reaction)

•First-line (H. pylori negative or NSAID-induced): PPI (e.g. lansoprazole or omeprazole) - acid suppression for mucosal healing

•NSAID-induced: stop the NSAID if clinically safe; if NSAID cannot be stopped, prescribe a PPI for gastroprotection

•Second-line (eradication failure) - quadruple therapy 10-14 days: PPI + bismuth subcitrate + tetracycline + metronidazole

•Confirm eradication: urea breath test or stool antigen test at least 4 weeks after antibiotics and 2 weeks after stopping PPI

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Long-term PPI risks: hyponatraemia, vitamin B12 deficiency, hypomagnesaemia, increased susceptibility to C. difficile, and acute interstitial nephritis - review ongoing need at every appointment.

Complications

•Upper GI bleeding - erosive gastritis → haematemesis/melaena; risk amplified by NSAIDs, aspirin, anticoagulants, SSRIs

•Peptic ulcer disease - untreated H. pylori → ulceration; perforation is a surgical emergency (pneumoperitoneum on erect CXR)

•Iron deficiency anaemia - chronic low-grade mucosal bleeding

•Pernicious anaemia - autoimmune atrophic gastritis → parietal cell destruction → intrinsic factor deficiency → B12 malabsorption → macrocytic megaloblastic anaemia + neurological sequelae

•Gastric adenocarcinoma - chronic H. pylori → intestinal metaplasia → dysplasia → adenocarcinoma (Correa cascade); H. pylori is a WHO Group 1 carcinogen

•Gastric MALT lymphoma - H. pylori-driven lymphoid proliferation; eradication of H. pylori induces remission in majority of low-grade MALT lymphomas