We started with a 72 year old gentleman who was having an elective pacemaker insertion. He had an isolated prolonged APTT and we have previously used the following flow chart to make a diagnosis:
It should be remembered that pre-analytical variables are the most common reasons for abnormal clotting screens. These include a tube not filled correctly, heparin contamination, taking too long to reach the laboratory, difficult venesection.
Although the history wasn’t ellicited initially after review the patient did have a history of prolonged bleeding following dental work and previously suffered from epistaxis. The clotting results showed:
- PT 14s (11-14s)
- APTT 47s (33-40s)
- APTT 50:50 mix immediate 38s
- APTT 50:50 mix at two hours 37s
- Thrombin time 16s (15-19)
- Fibrinogen (Clauss) 6.4g/L (1.5-4.5g/L)
- VIII 28% (50-100%)
- Two stage VIII 24%
- IX 79% (50-100%)
- XI 82% (65-100%)
- XII 80% (50-100%)
The factor VIII is low. An important differential diagnosis here is von Willebrand disease. Although the von Willebrand antigen and ristocein co-factor were normal, it can be difficult to exclude a rare type of von Willebrand disease (type 2N). Sometimes family history may help here. Genetic analysis can assist. In this case the patient had a genetic abnormality consistent with mild haemophilia A.
Rarely patients with mild haemophilia can go through life without significant bleeding problems. Here the history was key to identfy the bleeding disorder. In suspected cases of haemophilia when bleeding is occuring fresh frozen plasma is appropriate prior to knowledge of the factor assays. After VIII deficiency is confirmed specific treatment is required to replace this factor. In mild haemophilia A a combination of tranexamic acid and DDAVP (desmopressin) may be sufficient to stop any bleeding. DDAVP is contraindicated in patients with cardiac problems and at this age is usually avoided . Therefore recombinant VIII can be used.
Other important points to remember in the management are:
- Register with a haemophilia centre with a full MDT
- Family screening
- Antenatal counselling/carrier detection
- Appropriate out of hours access
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