Differential Diagnosis for a 5-week-old Boy with Vomiting
- Single most likely diagnosis
- Hypertrophic pyloric stenosis: This condition is characterized by forceful vomiting immediately after feeding, which is consistent with the patient's symptoms. The vomiting typically occurs after 1-2 ounces of liquid and is non-bilious, as described in the case. The age of the patient also fits with the typical presentation of hypertrophic pyloric stenosis, which usually occurs between 3-6 weeks of age.
- Other Likely diagnoses
- Gastroesophageal reflux: Although less likely than hypertrophic pyloric stenosis given the forceful nature of the vomiting, gastroesophageal reflux could still be a consideration, especially if the vomiting is posited to be related to the formula change or if there are other signs of reflux.
- Lactose intolerance or Protein malabsorption: These conditions could lead to vomiting after feeding, but they would typically be associated with diarrhea rather than the described mustard-colored seedy stools. However, they remain possibilities, especially if the formula change was not fully effective.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Duodenal atresia: Although the absence of bilious vomiting makes this less likely, any condition that could lead to intestinal obstruction, such as duodenal atresia, must be considered due to its severe consequences if not promptly diagnosed and treated.
- Rotavirus infection: While less common in this age group due to maternal antibody protection and the introduction of the rotavirus vaccine, a rotavirus infection could lead to severe dehydration and electrolyte imbalances, making it a critical diagnosis not to miss.
- Rare diagnoses
- Other metabolic disorders or congenital anomalies: There are numerous rare metabolic disorders or congenital anomalies that could present with vomiting in infancy. These would be considered if the more common diagnoses are ruled out and the patient's condition does not improve with standard treatments.