What is the likely diagnosis and management for a patient presenting with burning epigastric abdominal pain, one episode of emesis (vomiting), no diarrhea or constipation, and a normal Complete Blood Count (CBC), with symptoms suggestive of Gastroesophageal Reflux Disease (GERD) or Peptic Ulcer Disease (PUD)?

Likely Diagnosis and Immediate Management

The most likely diagnosis is peptic ulcer disease (PUD) or gastritis, and you should initiate empirical treatment with a proton pump inhibitor (omeprazole 20-40 mg once daily before meals) while arranging for H. pylori testing. 1, 2

Critical First Step: Exclude Life-Threatening Causes

Before proceeding with empirical treatment, you must immediately rule out cardiac causes, as myocardial infarction can present atypically with epigastric pain and carries 10-20% mortality if missed, particularly in women, diabetics, and elderly patients. 3, 4

• Obtain an ECG within 10 minutes of presentation and measure serial cardiac troponins at 0 and 6 hours—never rely on a single troponin measurement to exclude NSTEMI. 3, 4
• Check vital signs for tachycardia ≥110 bpm, fever ≥38°C, or hypotension, which predict perforation or sepsis. 3, 4
• Examine for peritoneal signs (rigidity, rebound tenderness, absent bowel sounds) indicating perforation, which carries 30% mortality if treatment is delayed. 5, 3

Most Likely Diagnosis: PUD or Gastritis

The clinical presentation of burning epigastric pain with one episode of emesis and normal CBC strongly suggests either peptic ulcer disease or gastritis. 5, 2

• Epigastric pain is the most common presenting symptom of PUD, often associated with nausea and vomiting. 2, 6
• PUD has an incidence of 0.1-0.3%, with complications occurring in 2-10% of cases, including bleeding (most common) and perforation (surgical emergency with up to 30% mortality). 5
• Approximately two-thirds of PUD cases are associated with H. pylori infection (42%) or NSAID use (36%). 7, 2
• The normal CBC makes significant bleeding less likely but does not exclude early or occult bleeding. 7

Differential Diagnosis to Consider

GERD is also highly plausible, affecting 42% of Americans monthly and 7% daily, presenting with heartburn, regurgitation, and epigastric pain. 5

• The burning quality of pain and single episode of emesis are consistent with both GERD and PUD, as symptoms overlap extensively between these conditions. 5
• A burning sensation starting in the epigastrium that radiates to the chest suggests GERD, while pain localized to the epigastrium without radiation favors PUD or gastritis. 5

Immediate Empirical Management

Start high-dose PPI therapy immediately (omeprazole 20-40 mg once daily before meals), which achieves healing rates of 80-90% for duodenal ulcers and 70-80% for gastric ulcers. 3, 1

• Omeprazole is FDA-approved for short-term treatment (4-8 weeks) of active duodenal ulcer, active benign gastric ulcer, and symptomatic GERD. 1
• Take omeprazole before a meal, typically once daily in the morning. 1
• Avoid NSAIDs, as they worsen PUD and increase bleeding risk. 3, 4

Essential Diagnostic Testing

Test for H. pylori infection using either breath testing or stool antigen testing, as eradication reduces the risk of duodenal ulcer recurrence. 1, 2

• If H. pylori is positive, initiate triple therapy: omeprazole with clarithromycin and amoxicillin for 10-14 days. 1
• The test-and-treat strategy is preferable in populations with moderate to high H. pylori prevalence (≥10%). 8

Indications for Upper Endoscopy

Endoscopy is not immediately necessary in this patient without alarm features, but consider it if symptoms persist after 4-8 weeks of PPI therapy. 5

• Alarm features requiring urgent endoscopy include: dysphagia, weight loss, persistent vomiting, hematemesis, anemia, or age >55 years with new-onset symptoms. 5, 3, 8
• Endoscopy is the gold standard for diagnosing PUD, gastritis, and esophagitis, allowing direct visualization, biopsy, and simultaneous H. pylori testing from tissue samples. 7
• If the patient fails to respond to twice-daily PPI therapy, endoscopy should be performed to evaluate for complications, Barrett's metaplasia, stricture, or alternative diagnoses. 5

Follow-Up Strategy

Reassess symptoms after 4 weeks of PPI therapy. 1, 8

• If symptoms resolve, stop treatment after 4-8 weeks; if symptoms recur, another course of the same treatment is justified. 8
• If symptoms persist despite adequate PPI therapy and negative H. pylori testing, consider upper endoscopy to exclude structural disease. 5, 8
• Most patients with duodenal ulcer heal within 4 weeks; some may require an additional 4 weeks of therapy. 1

Critical Pitfalls to Avoid

• Never dismiss cardiac causes based on age or "typical" GI presentation—always obtain ECG and serial troponins first. 3, 4
• Do not delay imaging if peritoneal signs develop, as perforated ulcer mortality increases significantly with delayed diagnosis. 5, 3
• Persistent vomiting excludes functional dyspepsia and mandates investigation for structural disease such as PUD or gastric outlet obstruction. 3, 4
• Do not assume GERD without excluding life-threatening causes first, even in patients with classic reflux symptoms. 3, 4

When to Consider CT Imaging

CT abdomen and pelvis with IV contrast is indicated if the diagnosis remains unclear after initial evaluation or if complications are suspected. 5

• CT findings suggestive of PUD include: gastric or duodenal wall thickening, mucosal hyperenhancement, fat stranding, focal wall defect/ulcer, or extraluminal gas (97% sensitive for perforation). 5
• However, CT is not the test of choice when PUD or gastritis is strongly suspected clinically—endoscopy remains the gold standard. 5