Differential Diagnosis for a 4-week-old Boy with Blood in Stool
- Single most likely diagnosis
- B) Cow milk protein allergy: This is the most likely diagnosis given the patient's age, symptoms, and recent introduction of infant formula (cow's milk protein) into his diet. The presence of blood in the stool, along with loose stools, is consistent with an allergic reaction to cow's milk protein.
- Other Likely diagnoses
- A) Anal fissure: Although less common in infants, an anal fissure could cause blood in the stool, especially if the infant is experiencing hard stools or constipation. However, the presence of loose, blood-tinged stools makes this diagnosis less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- C) Infectious enterocolitis: Although the infant appears well and is in no acute distress, infectious enterocolitis can rapidly progress and become severe, especially in young infants. It is essential to consider this diagnosis to ensure prompt treatment if necessary.
- D) Intussusception: This is a life-threatening condition that requires immediate attention. Although the infant's symptoms do not strongly suggest intussusception (e.g., no abdominal mass, no currant jelly stool), it is crucial to consider this diagnosis due to its potential severity.
- Rare diagnoses
- E) Juvenile polyps: Juvenile polyps are rare in infants and typically present with painless, bright red rectal bleeding. While possible, this diagnosis is less likely given the patient's age and symptoms. Note: Other rare diagnoses, such as gastrointestinal malformations or vascular anomalies, could also be considered but are not listed among the options.