Synopsis
Recognise acquired haemophilia and other factor inhibitors from unexpected bleeding and mixing-test patterns, achieve urgent haemostasis, and eradicate the inhibitor while limiting treatment-related infection and thrombosis.
- Suspect acquired haemophilia A in new extensive bruising, soft-tissue, mucosal, postpartum or postoperative bleeding with no lifelong history and an isolated prolonged APTT.
- First-line laboratory assessment is FBC, PT, APTT, fibrinogen, thrombin time, medicine and sample review, followed urgently by immediate and incubated mixing, factor VIII activity and Nijmegen Bethesda inhibitor titre.
- A mixing study that fails to correct after incubation supports a time-dependent inhibitor, but anticoagulants and lupus anticoagulant can confound it; interpret with the specialist laboratory.
Key red flags
Falling haemoglobin, hypotension, severe abdominal, back or groin pain, nerve deficit or tense swelling suggests concealed retroperitoneal or muscle haemorrhage and requires urgent imaging after haemostasis begins.
Investigation priorities
Define the bleeding consequence and localise the laboratory defect while detecting DIC or anticoagulant contamination.
Management branches
A bleeding adult has no known congenital disorder and PT is relatively preserved.
- Repeat a correctly collected peripheral sample and review UFH, LMWH, DOAC exposure, thrombin time and anti-Xa evidence.
- Request immediate and incubated mixing, factor VIII, IX and XI assays and lupus anticoagulant-informed interpretation with the coagulation laboratory.
Key medicines
Recombinant activated factor VIIGive eptacog alfa 90 micrograms/kg by intravenous bolus every 2–3 hours until haemostasis is achieved, then lengthen the interval according to sustained clinical response under the haemophilia-centre protocol.
Activated prothrombin-complex concentrateGive 50–100 units/kg intravenously every 8–12 hours according to bleeding response, with a maximum total dose of 200 units/kg in 24 hours.