What is the emergency department workup for a 2-month-old infant presenting with vomiting?

Emergency Department Workup for a 2-Month-Old Infant with Vomiting

For a 2-month-old infant presenting with vomiting in the emergency department, initial assessment should focus on identifying red flags requiring immediate attention, with appropriate imaging based on clinical presentation: abdominal radiography for suspected obstruction, ultrasound for non-bilious vomiting, and upper GI series for bilious vomiting. 1

Initial Clinical Assessment

• Thoroughly evaluate the nature of vomiting (bilious vs. non-bilious), timing, frequency, and associated symptoms such as fever, diarrhea, irritability, or lethargy 1
• Assess for dehydration through evaluation of thirst, capillary refill, tear production, mucosal dryness, and overall appearance 2
• Perform abdominal examination to identify distention, tenderness, or palpable masses 1
• Conduct neurological assessment, including evaluation for bulging fontanelle and altered mental status 1
• Check vital signs, as unstable vitals may indicate serious underlying conditions 3

Red Flags Requiring Immediate Attention

• Bilious vomiting is a surgical emergency until proven otherwise and requires immediate evaluation 1, 4
• Altered mental status or neurological signs necessitate prompt assessment 1
• Bloody vomiting or "currant jelly" stools suggest serious conditions like intussusception 4
• Abdominal distention or signs of obstruction require immediate attention 1
• Severe dehydration, toxic appearance, or excessive irritability warrant urgent care 5

Diagnostic Workup Based on Presentation

For Suspected Obstruction

• Abdominal radiography is the appropriate initial imaging study 6, 1
• If radiographs show classic double bubble or triple bubble with little or no gas distally, this suggests proximal bowel obstruction 6
• For distal bowel obstruction findings on radiographs, fluoroscopy contrast enema is usually appropriate 6

For Non-Bilious Vomiting (2 weeks to 3 months)

• Ultrasound of the abdomen is recommended as the initial imaging study to evaluate for hypertrophic pyloric stenosis 6, 1
• If pyloric stenosis is excluded and reflux is suspected, an upper GI series may be appropriate 6

For Bilious Vomiting

• Upper GI series is the appropriate next step after initial assessment to evaluate for malrotation with volvulus 6, 1
• Surgical consultation should be obtained promptly 1

Management of Dehydration

• For mild dehydration without red flags, oral rehydration therapy with small, frequent volumes is recommended 1, 7
• For a vomiting infant, administer oral rehydration solution in small amounts (one teaspoonful every 1-2 minutes) 7
• Continue breastfeeding for breastfed infants, as it reduces severity of diarrhea 7
• Consider lactose-free formulas for formula-fed infants with diarrhea and vomiting 7
• For severe dehydration or inability to tolerate oral fluids, hospitalization and IV rehydration may be necessary 7

Common Pitfalls to Avoid

• Delaying evaluation of bilious vomiting, which is a surgical emergency until proven otherwise 1
• Failing to recognize signs of increased intracranial pressure, such as bulging fontanelle 1
• Overlooking hypertrophic pyloric stenosis in infants 2 weeks to 3 months of age 1
• Using inappropriate fluids like cola drinks for rehydration, which can worsen diarrhea due to high osmolarity and low sodium content 7
• Relying solely on antiemetics without addressing the underlying cause 5, 3

Antiemetic Considerations

• Ondansetron (0.15 mg/kg parenteral or 0.2 mg/kg oral; maximum 4 mg) may be considered if the infant is unable to tolerate oral intake due to persistent vomiting 5
• Domperidone is another antiemetic option for persistent vomiting 3
• Antiemetics should not replace appropriate diagnostic workup for underlying causes 5