The causes can be divided into haematological and non-haematological

Haematological causes

• Platelet deficiencies - Cutaneous bleeding (Petechiae and purpura), immediate surgical bleeding, bleeding from mucous membranes (gyms, epistaxis, menorrhagia)
• Coagulation defects - Deep, often palpable ecchymosis, soft tissue haematomas, haemarthrosis

Coagulation defects

• Inherited - VWD (VIII), Haemophilia A (VIII), Haemophilia B (IX)
  • PC - brusing, haematomas and haemarthrosis usually start when the child starts to cruise, before they do signs could be excessive bleeding with circumcision, forceps or vacuum delivery, blood work
• Acquired - From consumption of factors or decreased production
  • Consumption - DIC, factor inhibitors (warfarin, autoantibodies)
  • Decreased production - Liver disease, vitamin K deficiency

Non-haematological causes

Dermatologic

Can be mistaken for bruises or bleeding under the skin

• Haemangiomas
• eczema
• congenital dermal melanocytosis (mangolian spots) - blue/grey birth marks with an irregular shape commonly at the base of the spine, buttocks, back or shoulders

Vascular

• Vasculitides - Most commonly IgA (henoch-schonlein pupura)
• Inherited connective tissue disorders - ehlers danlos