What is the differential diagnosis and initial management for a patient presenting with one week of gastric pain?

Differential Diagnosis and Initial Management for One Week of Gastric Pain

For a patient presenting with one week of gastric pain, immediately exclude life-threatening causes (myocardial infarction, perforated peptic ulcer, acute pancreatitis) before proceeding to test-and-treat for H. pylori or empirical PPI therapy based on age and alarm features. 1, 2

Immediate Priority: Exclude Life-Threatening Conditions

Obtain an ECG within 10 minutes to exclude myocardial infarction, which presents atypically with epigastric pain in women, diabetics, and elderly patients, with mortality rates of 10-20% if missed 1, 2. Check vital signs immediately for:

• Tachycardia ≥110 bpm, fever ≥38°C, or hypotension (predict perforation or sepsis) 2
• Physical examination for peritoneal signs (rigidity, rebound tenderness, absent bowel sounds) suggesting perforated peptic ulcer with 30% mortality if treatment delayed 2

Order serum lipase or amylase (≥2x normal for lipase, ≥4x normal for amylase) to diagnose acute pancreatitis, which characteristically presents with epigastric pain radiating to the back with 80-90% sensitivity and specificity 2.

Differential Diagnosis by Clinical Features

Most Common Causes (80% of cases):

• Functional dyspepsia (80% of patients with dyspepsia after investigation) 3
• Peptic ulcer disease (8% prevalence in community dyspepsia studies) 3
• Gastroesophageal reflux disease/erosive esophagitis (13% prevalence) 3
• H. pylori gastritis (modest association with dyspepsia symptoms) 3

Less Common but Important Causes:

• Gastric cancer (<0.5% prevalence, but critical to exclude in high-risk patients) 3
• Gastroparesis (overlapping features with functional dyspepsia) 3
• Celiac artery compression syndrome (evaluate with mesenteric duplex if suspected) 3
• Medication-induced (NSAIDs, aspirin) 3

Symptom Patterns to Guide Diagnosis:

• Epigastric pain or burning (suggests epigastric pain syndrome subtype of functional dyspepsia or peptic ulcer) 3
• Postprandial fullness or early satiation (suggests postprandial distress syndrome subtype) 3
• Pain radiating to back (consider pancreatitis or posterior penetrating ulcer) 2
• Heartburn predominant (GERD, not dyspepsia by definition) 3
• Persistent vomiting (suggests another disorder, not functional dyspepsia) 3

Initial Laboratory and Imaging Workup

Baseline Laboratory Tests:

• Full blood count in patients aged ≥55 years (NICE recommendation for raised platelet count) 3
• Complete blood count, C-reactive protein, serum lactate, liver and renal function tests to exclude serious organic pathology 2
• Coeliac serology in patients with overlap IBS-type symptoms 3
• H. pylori breath or stool testing (not serology, which has lower specificity) 1, 2

Imaging Indications:

CT abdomen/pelvis with IV contrast is the gold standard when diagnosis is unclear, identifying pancreatitis (mortality <10% overall but 30-40% in necrotizing pancreatitis), perforation (showing extraluminal gas in 97%), and vascular emergencies 3, 2. However, CT is not the initial test if acid reflux, esophagitis, gastritis, or peptic ulcer is strongly suspected 3.

Age-Based and Risk-Stratified Endoscopy Criteria

Urgent 2-Week Wait Endoscopy Indications:

• Age ≥55 years with dyspepsia AND weight loss 3, 1
• Age ≥40 years from areas at increased risk of gastric cancer OR with family history of gastro-oesophageal malignancy 3, 1

Non-Urgent Endoscopy Indications:

• Treatment-resistant dyspepsia if age ≥55 years 3
• Raised platelet count 3

Patients Who Can Proceed Directly to Empirical Management:

Patients <55 years without alarm symptoms (weight loss, anemia, dysphagia, persistent vomiting, hematemesis) can proceed to test-and-treat or empirical PPI therapy, as 80% will have functional dyspepsia 3, 1.

First-Line Management Algorithm

Step 1: Test-and-Treat for H. pylori (Preferred in Populations with ≥10% Prevalence)

Use carbon-urea breath testing or fecal antigen testing (not serology) for H. pylori diagnosis 1, 2, 4.

If H. pylori positive, prescribe triple therapy 1, 5:

• Omeprazole 20 mg + Amoxicillin 1000 mg + Clarithromycin 500 mg, all twice daily for 10 days
• Network meta-analysis shows test-and-treat ranks first in reducing symptoms at 12 months (RR 0.89; 95% CI 0.78-1.0) 1
• Eradication eliminates risk of peptic ulcer mortality 1

Step 2: Empirical PPI Therapy (If H. pylori Negative or Symptoms Persist After Eradication)

Omeprazole 20 mg once daily before meals for 4-8 weeks as first-line for ulcer-like dyspepsia (epigastric pain/burning) 1, 5, 4:

• Healing rates are 80-90% for duodenal ulcers, 70-80% for gastric ulcers 1, 5
• Most patients heal within 4 weeks; some require additional 4 weeks 5
• If no response after 2-4 weeks, switch drug class or increase dosing 1, 4

Step 3: Symptom-Based Adjustments

For predominant fullness, bloating, or early satiety (postprandial distress syndrome), consider prokinetic agents after PPI trial, though options are limited due to cisapride cardiac toxicity 3, 1.

For nausea, use Ondansetron 8 mg sublingual every 4-6 hours (obtain baseline ECG due to QTc prolongation risk), promethazine 12.5-25 mg orally/rectally every 4-6 hours, or prochlorperazine 5-10 mg every 6-8 hours 2.

Critical Pitfalls to Avoid

• Never dismiss cardiac causes in patients with "atypical" epigastric pain regardless of age—obtain ECG and serial troponins at 0 and 6 hours 1, 2
• Do not attribute persistent vomiting to functional dyspepsia—Rome IV criteria state this suggests another disorder and mandates investigation for structural disease 3, 2
• Do not delay endoscopy in patients with alarm features (weight loss, anemia, dysphagia, persistent vomiting, age ≥55 years), as missing gastric cancer or perforated ulcer leads to poor outcomes 3, 1, 2
• Avoid NSAIDs, which worsen peptic ulcer disease and are associated with dyspepsia in multiple population-based studies 3, 1
• Do not use H. pylori serology for test-and-treat strategy—use breath or stool testing only 1, 2
• Organize systematic follow-up after initiating test-and-treat strategy to ensure symptom resolution and identify patients requiring escalation to endoscopy 1

When Initial Management Fails

If patient fails to respond or relapses rapidly on stopping antisecretory therapy, apply the test-and-treat strategy before consideration of referral for endoscopy 4. Repetitive testing is not recommended once a diagnosis of functional pain is established; refer for psychological support (cognitive therapy) associated with available pharmacological options 6.