Table 3

 Initial and further investigations

Initial InvestigationFurther investigationConsider
PTIsolated prolongationEarly warfarin therapy; early vitamin K deficiency, early liver disease. Possible factor VII deficiency
aPTTIsolated prolongation: 50:50 plasma mixCorrection—factor deficiency, measure levelsFactor VIII or factor IX deficiency
von Willebrand disease
Factor XI deficiency (rare)
Factor XII deficiency (not associated with bleeding)
No correction—inhibitorLupus anticoagulant; heparin contamination
PT and APTTBoth prolonged (fibrinogen normal)Warfarin, vitamin K deficiency, heparin
Liver disease
Rare factor deficiencies, e.g. II, V, X
FibrinogenDecreasedProlonged PT and aPTT, decreased plateletsDisseminated intravascular coagulation
Severe liver disease
If <0.8 g/l, PT and aPTT will be prolongedDys/afibrinogenaemia
Platelets normal
Thrombin timeProlonged—reptilase timeNormalHeparin
Prolongedas for low fibrinogen
Factor VIIILow levels <40%Haemophilia A
Factor IXLow levels <40%Haemophilia B
von Willebrand factorLow antigen and/or activity (ristocetin co-factor) levelsvon Willebrand disease