Differential Diagnosis for a 29-Day-Old Infant Spitting Up a Lot

Single Most Likely Diagnosis

• Gastroesophageal Reflux (GER): This is the most common cause of spitting up in infants. It occurs when stomach acid flows back into the esophagus, causing discomfort and regurgitation. The symptoms typically peak around 4 months of age but can start as early as a few weeks old.

Other Likely Diagnoses

• Overfeeding or Incorrect Feeding Technique: Overfeeding or using an incorrect feeding technique can lead to excessive spitting up. This is common in bottle-fed infants but can also occur in breastfed babies.
• Food Allergy or Intolerance: An allergy or intolerance to a component of the infant's formula (in formula-fed babies) or to something in the mother's diet (in breastfed babies) can cause spitting up, along with other symptoms like rash or diarrhea.
• Infection: Gastrointestinal infections can cause vomiting and spitting up in infants.

Do Not Miss Diagnoses

• Pyloric Stenosis: A condition where the pylorus (the passage between the stomach and small intestine) thickens, blocking food from entering the intestine. It typically presents with projectile vomiting, which is different from the usual spitting up seen in reflux, and usually starts a bit later, around 3-6 weeks of age.
• Esophageal Atresia or Tracheoesophageal Fistula: Congenital anomalies of the esophagus that can cause severe feeding difficulties and regurgitation. These conditions are usually diagnosed shortly after birth but could potentially present later if mild.
• Hirschsprung's Disease: A condition affecting the large intestine, leading to severe constipation or intestinal obstruction. While primarily associated with constipation, it can also cause vomiting.

Rare Diagnoses

• Eosinophilic Esophagitis: A chronic inflammatory disease of the esophagus that can cause difficulty feeding, vomiting, and failure to thrive. It's more common in older children but can occur in infants.
• Congenital Diaphragmatic Hernia: A birth defect where there is a hole in the diaphragm, allowing abdominal organs to move into the chest and potentially causing feeding difficulties and regurgitation. This condition is usually diagnosed prenatally or shortly after birth.
• Metabolic Disorders: Certain metabolic disorders can cause vomiting and feeding difficulties in infants, though these are relatively rare and often present with other systemic symptoms.