😭 Chapter 26: Irritable Infant

Nelson's Pediatric Symptom-Based Diagnosis | Colic · GERD · Milk Protein Allergy · Abusive Head Trauma · Inconsolable Crying · Red Flags

🔍 Irritable Infant: Key Concepts

📊 Definition & Epidemiology
Irritable infant: excessive crying or fussiness in infant <1 year. <5-10% have serious underlying etiology. Crying peaks at 6 weeks, decreases by 3-4 months (normal crying curve).
🔄 Red Flags (Organic Causes)
Inconsolability, bilious vomiting, fever, lethargy, poor weight gain, focal neurologic signs, retinal hemorrhages, bruising (non-accidental trauma), abdominal distention, scrotal swelling (testicular torsion).
⚠️ Infantile Colic (Wessel Criteria)
Rule of 3s: crying >3 hours/day, >3 days/week, for >3 weeks. Otherwise healthy, thriving infant. Crying often in evening, legs pulled up, pained look. Resolves by 3-4 months.
💧 Gastrointestinal Causes
GERD (arching, postprandial), cow's milk protein allergy (bloody stools, vomiting, eczema), constipation, intussusception (currant jelly stool), volvulus (bilious vomiting).
🧬 Other Medical Causes
UTI (most common serious infection), corneal abrasion, otitis media, incarcerated hernia, hair tourniquet, fractures (occult), intracranial hemorrhage (abusive head trauma), sepsis, meningitis.
🚩 Child Abuse & Caregiver Education
Crying is a common trigger for abusive head trauma. Educate: Never shake a baby. If frustrated, place in safe crib and walk away. Provide resources for parental stress.

💡 Key Takeaway: Most irritable infants are normal (colic) but always rule out red flags (UTI, trauma, surgical abdomen). Crying is a trigger for abuse; educate all caregivers on safe responses. Trial of hypoallergenic formula if suspected milk protein allergy.

🩺 Clinical Approach to Irritable Infant: Step-by-Step Algorithm

🔹 Step 1: Triage for life-threatening causes
• ABCs: respiratory distress, shock, altered mental status.
• Signs of increased ICP (bulging fontanel, vomiting, sunset sign).
• Surgical abdomen: bilious vomiting, abdominal distention, absent bowel sounds, irreducible hernia.
🔹 Step 2: Identify red flags for serious illness
• Fever → consider UTI (most common serious bacterial infection in febrile infant), meningitis, sepsis, pneumonia.
• Poor feeding, lethargy, dehydration.
• Trauma: bruising in non-mobile infant, retinal hemorrhages, unexplained fractures.
• Scrotal swelling (testicular torsion), inguinal mass (incarcerated hernia).
🔹 Step 3: Evaluate for common non-emergent causes
• Colic: infant well otherwise, normal growth, crying predictable (Wessel criteria).
• GERD: arching, postprandial, poor weight gain, respiratory symptoms.
• Cow's milk protein allergy: vomiting, diarrhea, blood in stool, eczema, poor weight gain.
• Constipation: hard stools, abdominal distention.
• Otitis media: ear tugging, fever.
• Hair tourniquet: inspect digits, penis, clitoris.
🔹 Step 4: Diagnostic testing (if red flags)
• Febrile infant <3 months: CBC, blood culture, UA/UC, LP (if indicated).
• Suspected intussusception: abdominal ultrasound.
• Suspected abusive head trauma: CT head, skeletal survey, retinal exam.
• Suspected UTI: urinalysis and culture (catheter specimen).
🔹 Step 5: Management of colic and caregiver support
• Reassurance: normal crying curve, resolves by 3-4 months.
• Soothing techniques: swaddling, white noise, rocking, pacifier.
• If suspected milk protein allergy: trial of extensively hydrolyzed or amino acid formula (2 weeks).
• Avoid medications: simethicone, anticholinergics, sedatives not effective/harmful.
• Educate: Never shake a baby. Safe place (crib) and walk away if frustrated.