📊 Epidemiology
• 5% of irritable infants have serious medical disorder
• Most are normal or have minor issues (colic, teething)
• Thorough H&P yields diagnosis in majority
🩺 Colic – Most Common Cause
• Onset ~3 weeks, resolves by 3-4 months
• Crying >3 hours/day, >3 days/week, >3 weeks
• Usually evenings, infant otherwise well, normal growth
• Parental reassurance, support, avoid overstimulation
⚠️ Red Flags – Serious Causes
• Occult infection: UTI, meningitis, sepsis, otitis media
• Intussusception: paroxysmal pain, currant jelly stool, lethargy between episodes
• Corneal abrasion: fluorescein uptake, photophobia
• Hair tourniquet: swollen, discolored digit with hair wrapped
• Child abuse: inflicted injury, retinal hemorrhages, fractures
• Dactylitis (sickle cell): painful hand-foot swelling
📋 Other Causes
• Cow milk protein allergy (CMPA): bloody stools, fussiness, rash, improve with hydrolyzed formula
• Gastroesophageal reflux: arching, posturing (Sandifer), poor weight gain
• Teething: age-appropriate (~6 months), drooling, gum erythema
• Constipation: palpable stool, painful defecation
• Incarcerated hernia: irreducible inguinal mass
📌 Decision strategy: H&P guides evaluation. Consolable infant with normal exam is unlikely to have serious illness. Colic is diagnosis of exclusion. Always examine digits, test urine, check for occult blood in stool.