Lauren, 34 had a baby 4 months ago and recently consulted her GP with marked easy bruising. Her GP did some blood tests which revealed a prolonged APTT at 69 seconds. The lab did extra tests to establish than rather being deficient of one of the coagulation factors that are assessed by the APTT (8, 9, 11, 12) she had an inhibitor. For detailed information on how these tests are performed we would recommend you look at the excellent PracticalHaemostasis.com at:
Factor inhibitors are neutralising antibodies that develop against naturally occurring coagulation proteins. By far the most common of these is a factor VIII inhibitor, although this still only occurs in 0.5-1/1 million of the population. The majority of patients are in their 60s-70s.
Although an antibody that neutralises factor VIII essentially gives the patient severe Haemophilia A, the pattern of bleeding is different. Whilst boys/men with severe Haemophilia A bleed predominantly into joints and muscles, patients with acquired haemophilia develop bleeding into third spaces: soft tissues, mucosal membranes, the gastrointestinal and genitourinary tract. The bleeding into soft tissues can be staggering, but because of the rarity of the condition it remains a diagnosis that is frequently missed.
Associations with acquired haemophilia include:
- Being postpartum
- Underlying malignancy – particularly lymphomas/lymphoproliferative disorders.
- Other autoimmune disorders such as RA/SLE
- Drugs – depot anti-psychotics.
Once the diagnosis is made, management must be started immediately. The summary of this case will look at this in more detail.