What could be the cause of intermittent excessive crying and refusal to feed in a 5-month-old infant with a history of a minor fall from a surface less than 60cm, who otherwise feeds normally and had no signs of external injury after the fall?

Evaluation of Increased Crying in a 5-Month-Old Infant with Recent Fall

Given the history of a fall 2 days ago followed by new-onset intermittent crying episodes with feeding refusal, you must immediately evaluate for occult fractures or other trauma, as fractures are a recognized cause of crying in infants and this timing is highly suspicious. 1, 2

Immediate Diagnostic Priorities

Rule Out Trauma-Related Causes First

• Obtain skeletal survey or targeted imaging based on physical examination findings, as the temporal relationship between the fall and symptom onset (2 days) strongly suggests injury-related pain 1, 2
• Examine carefully for:
  • Clavicle fractures (most common in falls, may have minimal external signs) 2
  • Rib fractures (can cause pain with feeding/handling) 2
  • Long bone fractures (check for swelling, decreased movement, pain with passive range of motion) 2
  • Skull fractures (palpate entire skull for step-offs or boggy areas) 2

Exclude Other Serious Organic Causes

• Check serum glucose, calcium, and magnesium immediately, as these metabolic derangements commonly cause excessive crying and require urgent reversal 2
• Assess for concerning features that mandate workup: bilious vomiting, gastrointestinal bleeding, fever, lethargy, hepatosplenomegaly, or abdominal tenderness/distension 1, 2

Clinical Context and Differential Diagnosis

Why Trauma is Most Likely

• The timing is critical: Normal developmental crying peaks at 2-4 months and would be improving by 5 months, not suddenly worsening 1, 2
• The intermittent nature (1-2 episodes daily with normal feeding between) suggests pain triggered by specific movements or positions, not typical colic which presents with prolonged daily crying episodes 1, 3
• Feeding refusal combined with crying suggests pain exacerbated by being held or positioned for feeding 1

Alternative Considerations if Trauma Excluded

• At 5 months, this infant is past the typical colic age (peaks at 2-4 months, resolves by 3-4 months), making new-onset excessive crying atypical for benign developmental causes 1, 2, 4
• Consider cow's milk protein allergy if breastfed and mother recently changed diet, or if formula was recently switched, though this typically presents with more consistent symptoms 1
• Gastroesophageal reflux is unlikely unless accompanied by frequent vomiting (approximately 5 times daily) 4

Management Algorithm

If Fracture or Trauma Identified

• Provide appropriate analgesia (acetaminophen or ibuprofen at weight-based dosing) 2
• Immobilize/treat the specific injury as indicated 2
• Mandatory: Assess for non-accidental trauma given that falls <60cm rarely cause significant injury—inconsistency between history and findings requires child protective services involvement 2

If No Trauma Found

• Trial maternal dietary elimination (remove milk and eggs for 2-4 weeks) if breastfed 1
• Switch to extensively hydrolyzed formula if formula-fed and cow's milk protein intolerance suspected 1
• Implement soothing techniques: gentle motion, rhythmic movement, white noise, and avoid overstimulation 1, 2

Critical Safety Counseling

This is the peak age for abusive head trauma risk, with crying being the most common trigger and nearly 6% of parents of 6-month-old infants admitting to smothering, slapping, or shaking their infant at least once 1, 2

• Explicitly counsel parents that it's safe to put the baby down in a safe place and take a break if overwhelmed 1, 2
• Implement Period of PURPLE Crying education to improve parental knowledge and behavioral responses 2

Common Pitfalls to Avoid

• Do not dismiss the fall as insignificant simply because there were no immediate external injuries—internal injuries and fractures can present with delayed symptoms 1, 2
• Never prescribe proton pump inhibitors—they are ineffective for crying and carry risks including pneumonia and gastroenteritis 1, 2
• Do not assume this is normal developmental crying given the infant's age (5 months is past typical colic resolution) and acute onset after trauma 1, 2, 4