A 10 year old boy presents with mucosal bleeding of 1 week duration. The investigation of choice that will be most useful in him is –
💡 Explanation
## **Core Concept**
The question revolves around the diagnosis of a 10-year-old boy presenting with mucosal bleeding. Mucosal bleeding in children can be due to various causes, including infections, trauma, or bleeding disorders. The investigation of choice should aim to identify the underlying cause, particularly focusing on bleeding disorders or platelet-related issues.
## **Why the Correct Answer is Right**
The correct answer, **.**, refers to a Complete Blood Count (CBC) with a focus on platelet count and function or a peripheral smear. This is because mucosal bleeding in a child could be indicative of a platelet disorder, such as immune thrombocytopenic purpura (ITP), which is characterized by low platelet count due to immune-mediated destruction. A CBC is a fundamental investigation that provides immediate information on the platelet count, which can guide further management and investigation.
## **Why Each Wrong Option is Incorrect**
- **Option A:** While specific coagulation factor assays (like PT or aPTT) are crucial in diagnosing coagulopathies (e.g., hemophilia), they are not the first line in assessing mucosal bleeding in children, which more commonly points towards a platelet issue.
- **Option B:** Although a bone marrow examination can provide detailed information on the bone marrow's status, including production of blood cells, it is invasive and not the initial investigation of choice for mucosal bleeding.
- **Option D:** A specific test for von Willebrand factor or factor VIII might be considered if there's a strong suspicion of von Willebrand disease or hemophilia A, but these are not the first-line investigations for mucosal bleeding in a child.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that mucosal bleeding or petechiae in children should prompt an early investigation for thrombocytopenia or platelet dysfunction. ITP is a classic cause and should be considered early in the differential diagnosis. A rapid platelet count can help differentiate between ITP and other causes of bleeding.