What is the confirmatory test for a 9-year-old child with a 2-month history of epigastric pain, particularly when suspecting peptic ulcer disease (PUD) potentially related to Helicobacter pylori (H. pylori) infection?

Upper GI Endoscopy with Biopsy is the Confirmatory Test

For a 9-year-old child with 2 months of nocturnal epigastric pain and family history of peptic ulcer disease, upper GI endoscopy with biopsy is the confirmatory diagnostic test (Answer C). This allows direct visualization of ulcers, histopathological confirmation, and simultaneous H. pylori testing from tissue samples 1, 2.

Why Endoscopy is Confirmatory in This Clinical Context

This child has alarm features that mandate invasive testing:

• Chronic symptoms (2 months duration) in a pediatric patient with nocturnal pain pattern—a classic presentation for peptic ulcer disease 2
• Family history of PUD increases pretest probability and suggests possible H. pylori transmission within the household 3
• Age consideration: In children ≥10 years, primary peptic ulcer disease becomes more common with high recurrence rates 2

The combination of these factors moves this beyond a "test-and-treat" scenario into one requiring definitive diagnosis 1.

What Endoscopy with Biopsy Provides

Endoscopy is the only test that simultaneously:

• Directly visualizes ulcers and confirms their presence, location, and characteristics 1, 2
• Obtains tissue for histopathology to diagnose gastritis, assess for intestinal metaplasia, and detect other pathology that could explain symptoms 4
• Performs multiple H. pylori tests from biopsies: rapid urease test (sensitivity 80-95%, specificity 95-100%), histology, and culture for antimicrobial susceptibility if needed 5, 4
• Rules out other serious conditions including eosinophilic esophagitis, Crohn's disease, and malignancy 1, 2

At least two biopsy samples from both antrum and body should be obtained to improve sensitivity, as H. pylori colonization density varies 1, 5.

Why Other Options Are Insufficient as Confirmatory Tests

H. pylori Stool Antigen Alone (Option D)

While stool antigen testing has good accuracy (sensitivity/specificity ~93%) 5, 6, it only detects H. pylori infection—it does NOT confirm peptic ulcer disease 7, 4.

Critical limitation: A child can have H. pylori-positive gastritis without ulcers, or conversely, have peptic ulcers from other causes (NSAIDs, stress) without H. pylori 3. In one pediatric study, only 4 of 14 children with confirmed peptic ulcers were H. pylori-positive 3.

CBC (Option A)

CBC only detects complications like anemia from chronic bleeding—it cannot diagnose or confirm PUD 8.

Abdominal Ultrasound (Option B)

Ultrasound cannot visualize mucosal ulcers or gastritis 1. While CT can sometimes show gastric wall thickening or complications like perforation, imaging is not the test of choice when PUD is strongly suspected 1.

Clinical Algorithm for This Patient

Step 1: Proceed directly to upper endoscopy with biopsy given alarm features and chronic symptoms 1, 2

Step 2: During endoscopy, obtain:

• Multiple biopsies (≥2 from antrum, ≥2 from body) for histology 1, 5
• Tissue for rapid urease test 5, 4
• Consider culture if treatment failure is anticipated or in areas with high antibiotic resistance 5

Step 3: Ensure patient has discontinued:

• Proton pump inhibitors for ≥2 weeks before endoscopy 5
• Antibiotics for ≥4 weeks before testing 5

These medications cause false-negative results on tissue-based H. pylori tests.

Important Caveats

Watch for perforation: If this child develops sudden severe pain, fever, and abdominal rigidity, this represents perforation with mortality up to 30%—requiring immediate surgical consultation 2.

Post-treatment confirmation: After H. pylori eradication therapy, use non-invasive testing (urea breath test or stool antigen) ≥4 weeks after treatment completion—never use serology for confirmation 5.