Differential Diagnosis for a 3-year-old child with fever, abdominal pain, and foamy vomiting

Single most likely diagnosis

• Gastroenteritis: This is a common condition in children, often caused by viral infections, and can be exacerbated by the ingestion of something from a purse, potentially contaminated or toxic. The symptoms of fever, abdominal pain, and vomiting are classic for gastroenteritis.

Other Likely diagnoses

• Ingestion of a toxic substance: Given the history of possibly ingesting something from a purse, the child may have consumed a toxic substance such as medications, cosmetics, or cleaning supplies, leading to the current symptoms.
• Food poisoning: If the child ingested spoiled or contaminated food from the purse, food poisoning could be a likely diagnosis, presenting with similar symptoms.
• Viral gastroenteritis with secondary bacterial infection: The initial viral infection could lead to a secondary bacterial infection, worsening the symptoms.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

• Intussusception: Although less common, intussusception is a serious condition where a part of the intestine slides into another, causing severe abdominal pain and vomiting. It's crucial to consider this diagnosis due to its potential for severe complications if not promptly treated.
• Appendicitis: Appendicitis can present with abdominal pain, fever, and vomiting. Although less common in very young children, it's a critical diagnosis not to miss due to the risk of perforation and peritonitis.
• Ingestion of a caustic substance: If the child ingested a caustic substance from the purse, such as a battery or certain household chemicals, it could lead to severe esophageal and gastrointestinal damage, requiring immediate medical attention.

Rare diagnoses

• Foreign body obstruction: If the child ingested a solid object from the purse, it could potentially cause a foreign body obstruction in the gastrointestinal tract, leading to severe vomiting and abdominal pain.
• Pyloric stenosis: Although typically presenting in younger infants, pyloric stenosis could be considered in a child with persistent vomiting, especially if the vomiting is projectile in nature. However, the presence of fever and abdominal pain makes this diagnosis less likely.