Differential Diagnosis for a 6-week-old Girl with Persistent Vomiting
Single Most Likely Diagnosis
- Pyloric Stenosis: This condition is characterized by the thickening of the pylorus muscle, leading to gastric outlet obstruction. The symptoms of nonbilious, forceful vomiting after feeding, and the presence of peristaltic waves over the upper abdomen, are classic for pyloric stenosis. The age of the patient and the progression of symptoms also support this diagnosis.
Other Likely Diagnoses
- Gastroesophageal Reflux Disease (GERD): Although the vomiting is forceful, GERD could still be a consideration, especially if the infant has other symptoms such as arching of the back or fussiness during feeds. However, the absence of bilious vomiting and the specific pattern of vomiting after every feed make GERD less likely.
- Infectious Gastroenteritis: The presence of soft stools could suggest an infectious cause. However, the lack of fever, the nature of the vomiting (nonbilious and forceful), and the absence of other symptoms like diarrhea make this less likely.
- Formula Intolerance: Given that the infant is on a standard cow's milk-based formula, an intolerance could be considered, especially if there's a family history of allergies. However, the symptoms described do not fully align with typical presentations of formula intolerance.
Do Not Miss Diagnoses
- Intussusception: Although less common in this age group and typically presenting with bilious vomiting and abdominal pain, intussusception is a surgical emergency that must be considered, especially if there's any abdominal tenderness or blood in the stool.
- Congenital Adrenal Hyperplasia: The low potassium level could suggest an electrolyte imbalance, and congenital adrenal hyperplasia can present with vomiting, dehydration, and electrolyte disturbances. This condition is critical to diagnose early due to the risk of adrenal crisis.
- Inborn Errors of Metabolism: Certain metabolic disorders can present with vomiting, especially after feeding, due to the body's inability to metabolize certain components of the formula. These conditions can lead to severe illness if not identified and managed promptly.
Rare Diagnoses
- Antral Web or Other Gastric Obstructions: These are rare congenital anomalies that could cause similar symptoms of gastric outlet obstruction.
- Eosinophilic Gastroenteritis: A rare condition characterized by eosinophilic infiltration of the gastrointestinal tract, which could present with vomiting and intolerance to feeds.