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

Diagnosis: Inflammatory Bowel Disease (IBD)

The correct diagnosis is C - Inflammatory Bowel Disease, based on the presence of blood and mucus in stool with a positive fecal occult blood test, which are alarm features that exclude functional disorders and indicate organic inflammatory pathology requiring endoscopic evaluation. 1

Why IBD is the Correct Diagnosis

The clinical presentation contains critical alarm features that definitively point toward organic disease rather than functional disorders:

• Blood and mucus in stool with positive fecal occult blood test are pathognomonic for inflammatory colonic pathology, not functional disorders 1
• The British Society of Gastroenterology explicitly states that blood in stool is a clear alarm feature that rules out functional diagnoses like IBS or abdominal migraine 1
• The combination of mucus and blood specifically points to colonic inflammation, consistent with IBD presentation in pediatric patients 1
• This presentation is particularly common in children under 12 years, where IBD-unclassified (IBDU) occurs twice as frequently as in adults 2

Why Other Options Are Incorrect

Abdominal Migraine (Option A)

• Abdominal migraine is a functional disorder that never causes blood or mucus in stool 1
• The presence of positive fecal occult blood test completely excludes this diagnosis 1

Irritable Bowel Syndrome (Option B)

• IBS diagnosis requires the explicit absence of alarm symptoms, and blood in stool is definitively an alarm feature 1, 3
• While IBS can present with mucus passage, it does not cause blood in stool or positive fecal occult blood tests 1
• IBS is a functional bowel disorder that presumes the absence of structural or biochemical explanation for symptoms 1

Gastritis with Peptic Ulcer Disease (Option D)

• Peptic ulcer disease causes epigastric pain and vomiting but does not typically produce blood and mucus in stool 1
• Upper GI ulceration would cause melena (black tarry stools) or hematemesis, not the combination of blood and mucus characteristic of colonic inflammation 1
• The mucus component specifically indicates lower GI tract pathology, not upper GI disease 1

Diagnostic Approach for This Patient

Immediate investigations required:

• Complete blood count to assess for anemia, particularly important in younger patients with suspected IBD 1
• Erythrocyte sedimentation rate as inflammatory marker 1
• Fecal calprotectin and lactoferrin, which are highly sensitive for detecting intestinal inflammation 1
• Colonoscopy with biopsy to confirm diagnosis and determine disease extent - this is the definitive diagnostic test 1

Critical Clinical Pearls

• In children under 12 years, 4-23% of new onset IBD cases present with equivocal features and may initially be classified as IBDU 4
• Diagnosis requires comprehensive work-up including colonoscopy with ileal intubation, upper GI endoscopy, and small bowel imaging 4, 2
• The presence of blood and mucus mandates investigation for organic disease, particularly IBD, and cannot be dismissed as functional 1
• Sixty percent of pediatric IBDU cases are ultimately reclassified as UC or CD during follow-up 4