↑aPTT, normal PT; hemarthrosis / deep bleeds; X-linked male
Order first: Mixing study (corrects) → then Factor VIII (A) / IX (B) assay
Treat: Factor VIII / IX concentrate to target level; mild A → DDAVP
Order set
- aPTT, PT
- Mixing study
- Factor VIII/IX assay
Criteria
AdmitSignificant/deep/CNS bleed
ICUCNS bleed, airway/compartment
TransfuseFactor replacement to target; blood if major loss
DischargeBleed controlled, factor plan, haemophilia centre
Key
- Factor level must drop 70–80% before aPTT even rises.
- Emicizumab prophylaxis is now standard for hemophilia A (with or without inhibitors) — aPTT and FVIII one-stage assays are unreliable on emicizumab (use chromogenic); treat breakthrough bleeds with factor per inhibitor status (WFH 2020).
Clinical detail — differentials, red flags, pitfalls, disposition
Red flags
- Head/joint/deep bleeds
- Compartment syndrome
Differentials
- VWD
- Acquired inhibitor
- Heparin effect
Common mistakes
- Delaying factor replacement for imaging
- Missing inhibitor
Disposition & follow-up
Factor replacement; haemophilia centre follow-up.
Discharge package
MedicationsFactor replacement plan; avoid NSAIDs/IM injections
Follow-upHaemophilia centre
Warning symptomsJoint/deep bleeding, head injury
💊 Treatment detail — doses & preparation
Factor VIII concentratefactor replacement
DoseDose = weight × desired % rise × 0.5; major bleed target 100% then 50% ×3–7 d
PreparationReconstitute vial with supplied diluent; slow IV push
MonitorFactor level post-dose; inhibitor screen if no response
DDAVP (haemostasis)VWF releaser
Dose0.3 mcg/kg IV (max 20 mcg) over 30 min — type 1 VWD/mild haemophilia A
PreparationDilute in 50 mL NS; test-dose response before reliance
MonitorNa⁺, fluid restriction 24 h; tachyphylaxis with repeated doses
Tranexamic acidantifibrinolytic
Dose1 g IV/PO TDS (bleeding in VWD/haemophilia adjunct, menorrhagia)
Preparation500 mg tablets; IV 1 g in 50 mL NS over 10 min
MonitorAvoid with PCC/combined hormonal contraception (thrombosis); haematuria caution (clot colic)
Factor IX (haemophilia B)replacement
DoseDose = weight × desired % rise × 1; target 100% for major bleeds/surgery
PreparationReconstitute, slow IV push
MonitorFactor level; inhibitor screen
📖 WFH HaemophiliaReviewed July 2026