DIAGNOSTIC ALGORITHM

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Acquired hemophilia A is complicated to diagnose

Diagnosis of 89% of cases occurs after investigation of abnormal bleeding in patients with no personal or family history of bleeding conditions.8,10

Due to lack of familiarity with this rare condition, diagnosis is often delayed. Consult a specialist with expertise in managing patients with inhibitors.6

Diagnosis is dependent on accurate testing6,8

Upon initial assessment, laboratory results typically reveal prolonged activated partial thromboplastin time (aPTT) with normal prothrombin time (PT).6

An accurate mixing test is time- and temperature-dependent.6

  • Autoantibodies do not inhibit FVIII in normal plasma immediately
  • Tests performed without proper incubation time or temperature may result in missing AHA diagnosis
Diagnosis of Acquired Hemophilia A

Clinical presentation suggestive of AHA
and/or
Prolonged aPTT with normal PT

Exclude heparin contamination

Mixing study with normal plasma incubated for 1 to 2 hours at 37°C

aPTT does correct

aPTT does not correct

Exclude lupus anticoagulant (LA) by determining time and temperature dependence

Deficiency of FVIII,
FIX, FXI, or FXII

Specialist lab measures FVIII levels and inhibitor titers with Bethesda assay

ACQUIRED HEMOPHILIA A

REDUCED FVIII LEVELS AND THE PRESENCE OF FVIII ANTIBODY INHIBITOR TITER CONFIRM DIAGNOSIS8

CONSULT COMPREHENSIVE CARE HEMOPHILIA CENTER