What causes recurrent vomiting every 2 weeks in an 11-month-old infant?

Recurrent Vomiting Every 2 Weeks in an 11-Month-Old Infant

The most likely diagnosis in an 11-month-old with recurrent vomiting every 2 weeks is cyclic vomiting syndrome, though you must first urgently exclude surgical emergencies like intussusception and malrotation, particularly if the vomiting is bilious, forceful, or associated with abdominal pain, bloody stools, or lethargy. 1, 2, 3

Immediate Red Flags Requiring Urgent Evaluation

Before considering benign causes, you must rule out life-threatening conditions:

• Bilious (green) vomiting indicates obstruction distal to the ampulla of Vater and requires immediate surgical evaluation 1, 2, 4
• Bloody stools ("currant jelly" appearance) suggest intussusception, which is uncommon but possible at 11 months 1, 2
• Crampy, intermittent abdominal pain manifesting as inconsolable crying or leg drawing suggests intussusception 1, 2
• Forceful, projectile vomiting may indicate pyloric stenosis (though typically presents earlier, around 3-6 weeks) or increased intracranial pressure 1
• Altered mental status, bulging fontanelle, or enlarging head circumference suggests increased intracranial pressure from hydrocephalus, tumor, or trauma 1, 5
• Toxic appearance, fever, or lethargy raises concern for sepsis, meningitis, or metabolic disorders 1, 5

Most Likely Diagnosis: Cyclic Vomiting Syndrome

If red flags are absent and the vomiting follows a stereotypical pattern (same time of onset, similar duration, symptom-free intervals), cyclic vomiting syndrome (CVS) is the leading diagnosis 3:

• CVS typically presents between ages 3-7 years but can occur in infancy, with episodes of intense vomiting separated by weeks to months 3
• Episodes are stereotypical: same time of day onset, similar duration (hours to days), complete wellness between episodes 3
• Strong association with migraine headaches in the patient or mother suggests underlying mitochondriopathy 3
• Known triggers include infections, stress, certain foods, or sleep deprivation—identifying and avoiding these can prevent episodes 3

Other Common Differential Diagnoses

Gastroesophageal Reflux (GER)

• Most common cause of vomiting in infants, but typically presents as frequent regurgitation rather than episodic vomiting every 2 weeks 1
• Usually resolves with age and is associated with normal weight gain 1
• The 2-week interval pattern makes simple GER less likely 1

Recurrent Viral Gastroenteritis

• Appears in epidemics with sudden onset, mild fever, diarrhea, and short duration 1
• Less likely to follow a precise 2-week pattern 1, 5

Food Intolerance/Allergy

• Formula intolerance can cause recurrent vomiting but typically presents with additional symptoms like diarrhea, rash, or poor weight gain 1

Partial Intestinal Obstruction

• Malrotation can present at any age, not just in newborns, with decreasing frequency over time 1, 4
• Intermittent volvulus could theoretically cause episodic symptoms, though this would be unusual 1, 4

Metabolic or Neurologic Disorders

• Rare causes include inborn errors of metabolism, which may present with episodic vomiting triggered by illness or fasting 1, 5

Diagnostic Approach

Start with detailed history focusing on:

• Exact timing and pattern of episodes (onset time, duration, frequency) 3
• Character of vomitus (bilious, bloody, or non-bilious) 1, 2
• Associated symptoms (fever, diarrhea, abdominal pain, headache, lethargy) 1, 3
• Triggers (foods, stress, infections, sleep changes) 3
• Weight gain pattern and feeding tolerance between episodes 1
• Family history of migraines or similar vomiting patterns 3

Physical examination must include:

• Vital signs and hydration status 5, 6
• Abdominal examination for masses, distension, or tenderness 1, 6
• Head circumference and fontanelle assessment 1, 5
• Neurologic examination including fundoscopy if available 1, 6

Imaging and laboratory testing:

• If bilious vomiting or concern for obstruction: immediate abdominal X-ray and surgical consultation 1, 4, 5
• If intussusception suspected: ultrasound is the imaging modality of choice 1, 2
• If dehydration or red flags present: serum electrolytes, blood gases, renal and liver function tests 5
• If CVS suspected and diagnosis uncertain: consider metabolic screening, though most cases are diagnosed clinically 3

Management Strategy

For Acute Episodes (Abortive Treatment)

• Dark, quiet environment to minimize sensory stimulation 3
• Intravenous hydration if unable to tolerate oral fluids 5, 3
• Ondansetron (0.15-0.2 mg/kg, maximum 4 mg) for persistent vomiting preventing oral intake 5, 3, 7
• Consider sumatriptan, clonidine, or benzodiazepines for severe CVS episodes 3

Prophylactic Treatment for CVS

If episodes are frequent and disabling:

• Cyproheptadine (first-line in young children) 3
• Propranolol or amitriptyline as alternatives 3
• Trigger avoidance is crucial—identify and eliminate precipitating factors 3

For Other Diagnoses

• GER: dietary modifications, smaller frequent feeds, consider acid suppression if symptomatic 1
• Surgical causes: immediate surgical consultation and intervention 1, 2, 4

Critical Pitfalls to Avoid

• Never dismiss bilious vomiting as benign—it is a surgical emergency until proven otherwise 1, 2, 4
• Don't assume all recurrent vomiting is viral gastroenteritis—the stereotypical 2-week pattern demands consideration of CVS or other systemic causes 3
• Intussusception is unusual but not impossible at 11 months—maintain high suspicion if crampy pain or bloody stools develop 1, 2
• Avoid routine antiemetic use without identifying the underlying cause, as this may mask serious pathology 6
• Consider tube feeding if repeated episodes cause dehydration or failure to thrive, particularly in conditions like nephrogenic diabetes insipidus (though this typically presents with polyuria, not isolated vomiting) 1

Prognosis

• CVS has no reported mortality and many children outgrow it over time, though some develop migraine headaches or irritable bowel syndrome later 3
• Early recognition and appropriate management prevent complications like dehydration, esophageal tears, and unnecessary hospitalizations 3, 7