Chapter 19 · IBD & Colorectal Symptoms

Inflammatory bowel disease (epidemiology, etiopathophysiology, Crohn's disease, ulcerative colitis) · Rectal bleeding · Chronic gastrointestinal symptoms · Recurrent abdominal pain · Infantile colic · Chronic constipation · Chronic nonspecific diarrhea · Investigation of the colon
📌 Core principles: IBD incidence rising in children; Crohn's = transmural, skip lesions, perianal involvement; UC = continuous mucosal inflammation from rectum. Rectal bleeding in children: juvenile polyp, fissure, IBD, HSP. Recurrent abdominal pain: organic vs functional (Rome IV). Infantile colic: unexplained crying >3h/day >3 days/week. Chronic constipation: most common functional disorder; treat with PEG. Chronic nonspecific diarrhea (toddler's diarrhea): benign, high-volume, occurs in well child. Colon investigations: colonoscopy (gold standard), faecal calprotectin, radiology (barium enema), CT colonography, capsule endoscopy.

📖 IBD, Colorectal & Functional GI Disorders – Key Concepts

🩺 Inflammatory bowel disease (IBD)
Epidemiology: peak 15-30y, increasing in children. Etiology: genetics (NOD2, IL23R), dysbiosis, immune dysregulation. Crohn's: transmural, skip lesions, granulomas, strictures/fistulas, perianal. Ulcerative colitis: continuous mucosal inflammation from rectum, crypt abscesses, bloody diarrhoea. Extraintestinal: arthritis, uveitis, PSC, erythema nodosum.
🩸 Rectal bleeding in children
Painless: juvenile polyp, Meckel diverticulum, polyposis syndromes. Painful: anal fissure, infectious colitis, IBD. Massive: Meckel, angiodysplasia, vascular malformation. Haemorrhoids rare. Initial investigation: digital exam, stool culture, faecal calprotectin, endoscopy.
😖 Chronic abdominal pain & colic
Recurrent abdominal pain (RAP): organic (IBD, coeliac, PUD) vs functional (FAP, IBS, functional dyspepsia). Rome IV criteria. Infantile colic: <5 months, paroxysmal crying >3h/day >3d/week for >3 weeks, well otherwise. Management: reassurance, simethicone not effective.
🚽 Chronic constipation & nonspecific diarrhoea
Constipation: functional (95%), Hirschsprung, hypothyroidism, anorectal malformation. Treatment: disimpaction (PEG), maintenance, toilet training. Chronic nonspecific diarrhea (toddler's diarrhea): well child, 6-36 months, high-volume, loose stools with undigested food, no FTT. Manage: reassurance, avoid excess juice, high-fiber diet.
🔬 Investigation of the colon
Faecal calprotectin (≥150 µg/g suggests IBD). Colonoscopy with biopsies – gold standard (histology, extent, severity). Radiology: barium enema (transition zone Hirschsprung). CT colonography, capsule endoscopy (patency capsule first).

🔎 Symptom-based approach: rectal bleeding, chronic abdominal pain

1️⃣
Painless bright red blood per rectum, child well, normal growth – Juvenile polyp (most common). Digital rectal exam, colonoscopy with polypectomy.
2️⃣
Bloody diarrhea + abdominal pain + weight loss + extraintestinal symptoms – IBD. Faecal calprotectin, ileocolonoscopy with biopsies, MR enterography.
3️⃣
Recurrent abdominal pain (periumbilical) with normal exam, no red flags – Functional abdominal pain (FAP). Rome IV criteria, reassurance, low FODMAP trial if IBS features.
4️⃣
Infant <5 months with paroxysmal crying, flexed legs, no FTT – Infantile colic. Reassure parents, no medication, rule out organic cause (fissure, hernia, intussusception).
5️⃣
Toddler with loose, frequent stools containing undigested food, normal growth, well between episodes – Chronic nonspecific diarrhea (toddler's diarrhea). Increase dietary fat, limit juice, reassure.
⚠️ Red flags in chronic abdominal pain: Nocturnal awakening, weight loss, perianal disease, bloody stools, family history of IBD/coeliac, arthritis, oral ulcers, fever.

📋 Management algorithms: IBD, Constipation, Chronic diarrhea

🩺
Crohn disease – induction and maintenance
▪️ Mild-mod: exclusive enteral nutrition (EEN) 6-8 weeks (preferred first-line, avoids steroids).
▪️ Moderate-severe: systemic corticosteroids (prednisolone), then immunomodulators (azathioprine, MTX).
▪️ Anti-TNF (infliximab, adalimumab) for refractory/fistulizing disease.
▪️ Monitor growth, bone health, biannual colonoscopy.
🩸
Ulcerative colitis – step-up therapy
▪️ Mild-mod distal: 5-ASA (mesalamine) oral/rectal.
▪️ Extensive or moderate: oral corticosteroids (budesonide or prednisolone).
▪️ Severe acute (PUCAI >65): IV steroids; if no response day 3-5 → infliximab or ciclosporin.
▪️ Maintenance: 5-ASA, azathioprine, anti-TNF, tofacitinib (adults).
🚽
Functional constipation (Rome IV) – management
▪️ Disimpaction: oral PEG 3350 1-1.5 g/kg/day for up to 6 days.
▪️ Maintenance: PEG 0.5 g/kg/day for ≥2 months after regular stools.
▪️ Behavioural: toilet routine, reward system, avoid punishment.
🧪
Chronic nonspecific diarrhea (toddler's diarrhea)
▪️ Reassurance (normal variant).
▪️ Increase dietary fat (full-fat dairy), reduce excess fruit juice/fructose.
▪️ No medication; monitor growth.
🔬
Colon investigation algorithm
▪️ Faecal calprotectin (≥150 → high probability IBD).
▪️ Colonoscopy with multiple biopsies (gold standard).
▪️ Capsule endoscopy for small bowel Crohn (patency capsule first).

💡 Reflex prompts – IBD, Colic, Constipation, Investigations

🩺 A 12-year-old with chronic diarrhoea, abdominal pain, perianal skin tags, and weight loss. Likely diagnosis?
Crohn disease – perianal disease, skip lesions, granulomas. Faecal calprotectin elevated.
📊 A 5-year-old with painless bright red blood on toilet paper, normal growth. Most likely?
Juvenile polyp. Colonoscopy and polypectomy.
😖 Rome IV criteria for infantile colic?
Paroxysmal crying >3h/day, >3 days/week, for >3 weeks, in an otherwise healthy infant <5 months.
💩 First-line laxative for childhood functional constipation (disimpaction).
Polyethylene glycol 3350 (PEG, Movicol).
🩸 A child with recurrent abdominal pain, arthritis, uveitis, and oral ulcers. Diagnosis?
Inflammatory bowel disease (extraintestinal manifestations).
🔬 Most accurate non-invasive test to differentiate IBD from functional abdominal pain.
Faecal calprotectin (cutoff >150 µg/g).
🌿 A toddler with 6 loose watery stools per day, undigested food particles, normal growth, no FTT. Management?
Reassurance (chronic nonspecific diarrhea), dietary fat increase, limit juice.
🧫 Gold standard for diagnosis of ulcerative colitis.
Ileocolonoscopy with multiple biopsies (continuous inflammation, crypt abscesses).
💊 First-line induction therapy for moderate-to-severe paediatric Crohn (non-fistulizing).
Exclusive enteral nutrition (EEN) – 6-8 weeks, equivalent to steroids, better growth.
⚠️ A child with bloody diarrhoea, fever, abdominal pain, and faecal calprotectin 1200. Next test?
Colonoscopy with biopsies to differentiate IBD from infection.