What is the diagnosis for a 12-year-old with recurrent epigastric pain, occasional vomiting, and stool positive for blood and mucus, with a positive occult blood test?

Diagnosis: Inflammatory Bowel Disease (C)

The correct diagnosis is inflammatory bowel disease (IBD), as the presence of blood and mucus in stool with a positive fecal occult blood test is pathognomonic for inflammatory colonic pathology and definitively rules out functional disorders. 1, 2

Why IBD is the Correct Answer

Blood and Mucus Are Alarm Features That Exclude Functional Diagnoses

• Blood in stool is explicitly an alarm feature that rules out functional diagnoses like abdominal migraine and irritable bowel syndrome according to the British Society of Gastroenterology 1, 2
• IBS diagnosis requires the explicit absence of alarm symptoms, and blood in stool is definitively an alarm feature that precludes this diagnosis 1, 2
• Abdominal migraine is a functional disorder that never causes blood or mucus in stool 2
• The combination of mucus and blood specifically points to colonic inflammation, consistent with IBD presentation in pediatric patients 2

Why Not Peptic Ulcer Disease/Gastritis (Option D)

• Peptic ulcer disease causes epigastric pain and vomiting but does not typically produce blood and mucus in stool 1, 2
• The combination of mucus and blood points to colonic inflammation, not upper GI ulceration 1
• While PUD can cause melena (digested blood), it does not produce the characteristic combination of fresh blood with mucus seen in colonic inflammation 1

Clinical Reasoning Algorithm

Step 1: Identify Alarm Features

• Blood in stool: Present ✓
• Mucus in stool: Present ✓
• Positive fecal occult blood test: Present ✓
• These findings mandate investigation for organic disease, particularly IBD 1, 2

Step 2: Localize the Pathology

• Blood + mucus = colonic inflammation (not upper GI) 1, 2
• Epigastric pain in IBD can occur due to referred pain or concurrent upper GI involvement
• In children under 12 years, 4-23% of new onset IBD cases present with equivocal features 2

Step 3: Required Diagnostic Work-Up

Immediate laboratory tests:

• Complete blood count to assess for anemia (particularly important in younger patients) 1, 2
• Erythrocyte sedimentation rate as an inflammatory marker 1, 2
• Fecal calprotectin and lactoferrin (highly sensitive for detecting intestinal inflammation) 1, 2

Definitive diagnostic testing:

• Colonoscopy with biopsy is the definitive diagnostic test to confirm diagnosis and determine disease extent 1, 2
• Comprehensive work-up should include colonoscopy with ileal intubation, upper GI endoscopy, and small bowel imaging 2

Critical Clinical Pearls

• The presence of blood and mucus mandates investigation for organic disease and cannot be dismissed as functional 2
• Sixty percent of pediatric inflammatory bowel disease unclassified (IBDU) cases are ultimately reclassified as ulcerative colitis or Crohn's disease during follow-up 2
• The British Society of Gastroenterology emphasizes that IBS diagnosis requires absence of alarm symptoms, and blood in stool is a clear alarm feature 1
• Fecal markers like calprotectin and lactoferrin are highly sensitive for detecting intestinal inflammation and should be obtained before endoscopy 1