What is the differential diagnosis and treatment approach for an adult patient with no significant past medical history presenting with symptoms of gastrointestinal distress, to distinguish between gastroenteritis and gastritis?

Distinguishing Gastroenteritis from Gastritis: Clinical Approach

Gastroenteritis and gastritis are fundamentally different conditions requiring distinct diagnostic and treatment approaches: gastroenteritis is an acute infectious inflammation of the stomach and intestines typically presenting with diarrhea, while gastritis is inflammation of the gastric mucosa alone, usually presenting with epigastric pain without diarrhea. 1, 2

Key Clinical Distinctions

Gastroenteritis Presentation

• Diarrhea is the hallmark symptom, often accompanied by vomiting, nausea, and abdominal cramping 1
• Acute onset (symptoms typically resolve within one week in mild cases) 1
• May present with fever, particularly in bacterial or parasitic infections 1
• Systemic symptoms including dehydration are common 1
• Viruses are the most common cause, followed by bacteria and parasites 1

Gastritis Presentation

• Epigastric pain is the predominant symptom, often described as burning or gnawing 3
• Diarrhea is typically absent (this is the critical distinguishing feature) 2
• May include nausea, vomiting, early satiety, and bloating 3
• Symptoms are often chronic or recurrent rather than acute 3, 2
• Most commonly caused by Helicobacter pylori infection or NSAID use 4

Diagnostic Algorithm

Initial Clinical Assessment

Look for these specific red flags that mandate immediate evaluation:

• Occult or visible blood in stool (suggests peptic ulcer disease complication or severe gastritis) 4
• Fever with tachycardia and severe epigastric pain (concern for perforation with mortality up to 30%) 4
• Sudden severe epigastric pain with abdominal rigidity (perforation requiring immediate surgical consultation) 4
• Retrosternal pain (suggests coexisting esophagitis) 4

Testing Strategy Based on Presentation

For suspected gastroenteritis (diarrhea predominant):

• Mild symptoms resolving within one week: no microbial studies needed 1
• Severe or prolonged symptoms (>1 week), bloody stool, or recent antibiotic use: multiplex antimicrobial testing is preferred over traditional stool cultures 1
• Recent antibiotic exposure: test specifically for Clostridioides difficile 1

For suspected gastritis (epigastric pain without diarrhea):

• Upper endoscopy with biopsy is the confirmatory diagnostic test when alarm features are present (age >50, weight loss, dysphagia, bleeding, family history of gastric cancer) 4
• Endoscopy allows direct visualization, histopathological confirmation, and simultaneous H. pylori testing from tissue samples 4
• Obtain at least two biopsy samples from both antrum and body to improve sensitivity for H. pylori detection 4
• CT abdomen may show gastric wall thickening (>5mm), mucosal hyperenhancement, or fat stranding, but is not first-line 3

Treatment Approach

Gastroenteritis Management

Hydration is the cornerstone of therapy:

• Mild to moderate symptoms: oral rehydration if tolerated 1
• Severe illness: nasogastric or intravenous hydration 1
• Symptom control: antiemetic, antimotility, and/or antisecretory drugs as needed 1

Antimicrobial therapy is indicated only for:

• C. difficile infections 1
• Travel-related diarrhea 1
• Bacterial infections with severe symptoms 1
• Parasitic infections 1

Gastritis Management

First-line therapy depends on etiology:

• Test and treat H. pylori infection if present using high-potency PPIs (esomeprazole 20-40mg or rabeprazole 20-40mg twice daily) combined with antibiotics 3, 4
• For H. pylori-negative gastritis: proton pump inhibitors remain first-line for acid suppression 3
• Avoid pantoprazole due to lower potency (40mg pantoprazole = 9mg omeprazole equivalent) 3
• Discontinue NSAIDs if they are the causative agent 4

For patients with severe atrophic gastritis:

• Screen for iron and vitamin B-12 deficiency (iron deficiency occurs in up to 50% of corpus-predominant cases) 3
• Consider endoscopic surveillance every 3-5 years for gastric cancer risk 3
• Screen for autoimmune thyroid disease in autoimmune gastritis 3

Critical Pitfalls to Avoid

Do not assume gastritis based on epigastric pain alone - symptoms overlap extensively between GERD, gastritis, esophagitis, and peptic ulcer disease, requiring careful history and often endoscopic evaluation 3, 4

Do not order imaging as first-line for suspected gastritis - endoscopy is superior for diagnosis and allows therapeutic intervention 4

Do not miss postinfectious complications - approximately 9% of patients with acute gastroenteritis develop postinfectious IBS, accounting for more than 50% of all IBS cases 1

Recognize eosinophilic gastritis as a rare but important differential - presents with recurrent vomiting, abdominal pain, and peripheral eosinophilia; requires tissue diagnosis and responds to corticosteroids 5, 6, 7