Any acute or recent onset of bleeding symptoms in a patient with no previous history of bleeding, especially in elderly or post-partum patients, and an unexplained isolated prolonged activated partial thromboplastin time (aPTT) suggest the diagnosis of AHA, and need further investigation. The differential diagnosis in prolonged aPPT with a normal prothrombin time (PT) includes factor deficiencies, lupus anticoagulant or heparin therapy. The first step to distinguish between factor deficiency and the presence of an inhibitory substance is to perform a mixing test, in which patient plasma and normal plasma are mixed and aPTT measured; correction of prolonged aPTT suggests a factor deficiency while persistent prolongation indicates the presence of an inhibitor. Prolongation of the aPTT in a mixture of patient and normal plasma after a 1-2 h incubation compared to an immediate mix is typical of FVIII autoantibodies, as FVIII inhibitors are time and temperature-dependent. The diagnosis is confirmed by the subsequent identification of reduced FVIII levels with evidence of FVIII neutralising activity (titrated using the Bethesda assay or the Nijmegen modification).
Acquired haemophilia
Harris platelet syndrome
Haemophilia
Quebec platelet disorder
Hypodysfibrinogenemia
Congenital afibrinogenemia
Dysfibrinogenemia
Von Willebrand disease