Differential Diagnosis for a 9-Month-Old Girl with Fever and Poor Feeding
- Single Most Likely Diagnosis
- Urinary Tract Infection (UTI): The presence of positive nitrites and leukocyte esterase in the urinalysis strongly suggests a UTI. The symptoms of fever, poor feeding, and slightly loose stools are also consistent with a UTI in an infant.
- Other Likely Diagnoses
- Viral Gastroenteritis: Although the stools are non-bloody and only slightly loose, viral gastroenteritis could still be a consideration, especially given the fever and poor feeding.
- Upper Respiratory Tract Infection: The fussiness and fever could be indicative of an upper respiratory tract infection, although the clear tympanic membranes and lack of other respiratory symptoms make this less likely.
- Roseola: This viral illness is common in infants and can cause high fever, fussiness, and sometimes gastrointestinal symptoms.
- Do Not Miss Diagnoses
- Bacterial Meningitis: Although the fontanelle is open, soft, and flat, and there are no specific signs of meningismus, bacterial meningitis is a potentially deadly condition that must be considered in any infant with fever and altered behavior.
- Sepsis: The presence of fever, tachycardia, and poor feeding could be indicative of sepsis, especially if the UTI is not promptly treated or if there is another underlying infection.
- Intussusception: Although less common, intussusception can cause fever, abdominal symptoms, and sometimes loose stools in infants.
- Rare Diagnoses
- Pyloric Stenosis: This condition typically presents with projectile vomiting, which is not mentioned in the scenario, but could be considered if the infant's symptoms worsen or if other diagnoses are ruled out.
- Inborn Errors of Metabolism: Certain metabolic disorders can cause episodes of fever, poor feeding, and altered behavior, although these are relatively rare and would typically require additional symptoms or laboratory findings to consider.