Differential Diagnosis for 2 Month Old with Watery Diarrhea Exclusively Breastfed

• Single Most Likely Diagnosis
  • Breast milk oversupply or foremilk imbalance: This is a common issue in exclusively breastfed infants, where the baby receives too much foremilk (which has a higher water content) and not enough hindmilk (which is richer in fat), leading to watery stools.
• Other Likely Diagnoses
  • Viral gastroenteritis: Although less common in exclusively breastfed infants due to the protective effects of breast milk, viral infections can still cause diarrhea.
  • Introduction of a new food or substance to the mother's diet: Sometimes, a new food or substance in the mother's diet can cause an allergic reaction or intolerance in the baby, leading to diarrhea.
  • Overfeeding: Frequent or prolonged feedings can lead to an overload of the infant's digestive system, resulting in watery diarrhea.
• Do Not Miss Diagnoses
  • Congenital lactase deficiency: A rare condition where the infant is unable to digest lactose, a sugar found in breast milk, leading to severe diarrhea.
  • Bacterial infection (e.g., Salmonella, E. coli): Although less common, bacterial infections can cause severe diarrhea in infants and require prompt medical attention.
  • Intestinal obstruction or other anatomical issues: Conditions like intestinal atresia or stenosis can cause diarrhea and require immediate medical intervention.
• Rare Diagnoses
  • Allergic proctocolitis: An allergic reaction to a protein in the mother's diet (e.g., cow's milk, soy) that is passed through breast milk, causing inflammation and diarrhea in the infant.
  • Inborn errors of metabolism: Certain metabolic disorders, such as galactosemia, can cause diarrhea in infants due to an inability to properly metabolize certain nutrients.