Thankyou for your input this week!This week we had a look at a few abnormalities that can be seen on coagulation screens in a pre procedure setting.
The first thing to say is there is no replacement for a good old fashioned bleeding history! Patients may have a significant bleeding history, as seen in our second case, but with a normal coagulation screen.
With all patients a medication history and family history, if there is a bleeding tendency, should be asked.
Our first patient was found to have a prolonged aptt and intrinsic factors were checked. These revealed a low factor XII, which is of no clinical significance and shouldn’t produce a bleeding tendency.
Our second case was slightly more interesting with a significant operative bleeding history but apparent normal coagulation screen. A number of tests were normal, but a 2-stage factor VIII was low. Patients with haemophilia may have a discrepant 1 and 2 stage assay, and their bleeding may be out of proportion to their apparent 1 stage factor 8. Certain genetic mutations have been associated with this – e.g. Factor VIII A3 domain mutation. Below is a link to a nice case report of this.
Our 3rd case this week looked at a patient with vasculitis who was on plasma exchange, who had a prolonged APTT. When a patient is on exchange it is important to enquire whether they are being exchange with as clotting factors can be depleted.
The thrombin time on this sample was >300, with a normal reptilase and protamine time. Thus indicating heparin contamination.
A peripheral blood sample was taken showing a normal coagulation screen.
So that was a whistle stop tour of a couple of clotting cases, highlighting the importance of a good history!
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