A 20-year-old female presented with complaints of easy bruising, frequent episodes of nose bleed, menorrhagia and few episodes of upper GI bleed also. On examination, purpura and petechial rash were noted. Lab findings revealed, Thrombocytopenia PT- normal aPTT- normal Platelets do not aggregate in response to ristocetin after adding normal plasma Platelets have normal aggregation in response to adenosine diphosphate, epinephrine, and collagen. Normal platelet granules What is the most likely diagnosis in the above patient: –

**Core Concept**
The patient's symptoms suggest a bleeding disorder, characterized by easy bruising, nosebleeds, menorrhagia, and upper GI bleeding, with laboratory findings indicating thrombocytopenia and abnormal platelet function. The **platelet aggregation disorder** is likely due to a defect in platelet adhesion or aggregation, given the normal coagulation profile (PT and aPTT).

**Why the Correct Answer is Right**
The correct diagnosis is likely related to a deficiency in **von Willebrand factor (vWF)**, which is essential for platelet adhesion and aggregation, particularly in response to **ristocetin**. The patient's platelets do not aggregate in response to ristocetin, even after adding normal plasma, suggesting a deficiency in vWF. However, aggregation is normal in response to other agonists like **adenosine diphosphate**, **epinephrine**, and **collagen**, indicating that the platelets themselves are functional.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because it does not specifically relate to the patient's presentation and lab findings.
**Option B:** Similarly, this option does not match the patient's clinical and laboratory profile.
**Option C:** This choice is also incorrect as it does not align with the provided information.
**Option D:** Without the specific details of each option, we can infer that any option not related to vWF or a similar platelet adhesion/aggregation defect would be incorrect.

**Clinical Pearl / High-Yield Fact**
The key point to remember is that **von Willebrand disease** is the most common hereditary bleeding disorder, characterized by a deficiency or dysfunction of vWF, leading to easy bruising, nosebleeds, and other mucocutaneous bleeding symptoms. The diagnostic clue is the lack of platelet aggregation in response to ristocetin.

**Correct Answer:** D. von Willebrand disease

✓ Correct Answer: A. Bernard-soulier syndrome