Differential Diagnosis for Rectal Bleeding in an 18-month-old Girl
- Single most likely diagnosis
- D) Meckel diverticulum: This condition is a common cause of painless, bright red rectal bleeding in infants and young children, especially in those under 2 years of age. The presence of a second episode of significant bleeding and a low mean corpuscular volume (indicating microcytic anemia) supports this diagnosis, as Meckel diverticulum can cause chronic blood loss leading to anemia.
- Other Likely diagnoses
- A) Constipation: Although constipation can cause rectal bleeding, it is usually associated with pain and discomfort during defecation, which is not mentioned in the scenario. However, it remains a possibility, especially if the bleeding is not as voluminous as described.
- E) Ulcerative colitis: This is less likely given the age of the patient and the absence of other symptoms such as abdominal pain, diarrhea, or weight loss. However, it cannot be entirely ruled out without further investigation.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- C) Intussusception: Although intussusception typically presents with abdominal pain, vomiting, and currant jelly stool (a mixture of blood and mucus), it is a medical emergency that requires prompt diagnosis and treatment. The absence of abdominal pain in this case makes it less likely, but it should not be missed due to its potential severity.
- B) Duodenal ulcer: While duodenal ulcers are rare in infants and toddlers, they can cause significant bleeding. The presentation might not always include abdominal pain, especially in young children who may not be able to communicate their discomfort effectively.
- Rare diagnoses
- Other rare causes of rectal bleeding in children, such as vascular malformations, hemangiomas, or inflammatory bowel disease (other than ulcerative colitis), could be considered but are less likely given the information provided. These would typically require more specific symptoms or findings on examination and would be investigated further if the more common causes are ruled out.