AHA: acquired hemophilia A; aPTT: activated partial thromboplastin time; PT: prothrombin time.
* A mixing study is usually faster than a factor VIII activity level in most institutions. Both should be obtained, and if one is suggestive, treatment can be started for bleeding if needed while awaiting results of the confirmatory testing. The initial mixing study can be normal (aPTT corrects) in acquired hemophilia A, but the aPTT prolongs after the 2-hour incubation at 37°C because the inhibitors are time- and temperature-dependent.
¶ Confirmatory testing includes factor VIII activity, mixing study with 2-hour incubation at 37°C, and inhibitor titer by Bethesda assay. Tests that are already done do not need to be repeated; tests that were not yet done should be obtained. Acquired hemophilia A is characterized by:Do you want to add Medilib to your home screen?