Haemorrhagic diathesis ( coagulopathy, platelet disorder)

1. Big picture

Haemorrhagic diathesis means an abnormal tendency to bleed. In pediatrics, the examiner mainly wants you to recognize the bleeding pattern, because the pattern tells you where the defect is.

The key distinction:

Mucocutaneous bleeding
→ platelet number/function or von Willebrand disease

Deep bleeding into joints/muscles
→ coagulation factor deficiency, especially hemophilia

So your first clinical question is not “What is the platelet count?” but:

Is this platelet-type bleeding or coagulation-type bleeding?

Then confirm with basic hemostasis tests:

CBC + platelet count + smear
PT/INR
aPTT
fibrinogen
D-dimer if DIC suspected

Initial evaluation of bleeding disorders in children commonly begins with complete blood count, peripheral smear, prothrombin time, activated partial thromboplastin time, and fibrinogen. ([UpToDate][1])

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