Differential Diagnosis for Upset in a 3-Month-Old

Single Most Likely Diagnosis

• Gastroesophageal Reflux Disease (GERD): This is a common condition in infants, characterized by the backflow of stomach contents into the esophagus, leading to discomfort and fussiness. The age of the infant and the presentation of being upset are consistent with GERD.

Other Likely Diagnoses

• Overfeeding or Underfeeding: Both can cause discomfort and fussiness in infants. Overfeeding can lead to regurgitation and discomfort, while underfeeding can result in hunger and irritability.
• Gas and Colic: Infants, especially at this age, can experience gas and colic, which are common causes of fussiness and discomfort.
• Infection (e.g., Urinary Tract Infection, Otitis Media): Although less common, infections can cause irritability and fussiness in infants. A thorough examination and possibly some diagnostic tests may be needed to rule out infections.

Do Not Miss Diagnoses

• Intussusception: A serious condition where a part of the intestine slides into an adjacent part, potentially cutting off blood flow. It's a medical emergency and can present with sudden onset of severe abdominal pain, vomiting, and bloody stools.
• Volvulus: A condition where the intestine twists, cutting off its blood supply. It's a surgical emergency and can present with severe abdominal pain, vomiting, and bloody stools.
• Hirschsprung's Disease: A congenital condition affecting the large intestine, leading to severe constipation or intestinal obstruction. Early diagnosis is crucial for effective management.
• Child Abuse: Unfortunately, child abuse is a reality and can present with unexplained injuries or behavioral changes. Healthcare providers must be vigilant and consider this in their differential diagnosis.

Rare Diagnoses

• Food Allergy or Intolerance: Although less common, some infants may have an allergy or intolerance to certain foods, which can cause discomfort and fussiness.
• Metabolic Disorders: Certain metabolic disorders, such as galactosemia, can present with nonspecific symptoms like irritability and feeding difficulties in infants.
• Neurological Conditions: Rare neurological conditions, such as infantile spasms or other seizure disorders, can cause changes in behavior or fussiness in infants.

Each of these diagnoses requires careful consideration of the infant's symptoms, medical history, and possibly further diagnostic testing to determine the underlying cause of the upset.