Bleeding Disorders Flashcards
Define bleeding disorder.
Abnormal condition which allows blood to escape from injured vessels or interferes with haemostasis following injury
Describe primary and secondary haemostasis.
In life, both are triggered simultaneously
Primary haemostasis = reflex constriction of blood vessels and formation of platelet plug
Secondary haemostasis = stabilisation of platelet plug by fibrin, which results from activation of clotting cascade
What is von Willebrand’s disease?
Deficiency of vWF (involved in primary haemostasis - protein either not manufactured or not enough
Platelet adhesion/clumping impaired
How does liver disease lead to coagulopathies?
All clotting factors made in liver!
Vitamin K-dependent clotting factors in pathway - vitamin K bound up by rodenticides leading to bleeding disorders
Also when anorexic or problems with fat digestion due to blocked bile ducts (stone/pancreatitis)
Describe the cascade that leads to fibrin production.
Intrinsic and extrinsic pathway come together to common pathway
Prothrombin converted to thrombin
Thrombin catalyses conversion of fibrinogen to fibrin
What defects of primary haemostasis can exist?
Decreased no. of platelets (thrombocytopenia) e.g. IMTP, infectious diseases
Functional (platelets cannot stick together) e.g. end-stage CKD, multiple myeloma
Vasculitis e.g. adder bite
What defects of secondary haemostasis can exist?
Quantitative e.g. decreased amount of clotting factors
Qualitative e.g. reduced function of clotting factors
What history should we take for potential bleeding disorders?
Inherited disorders usually < 6 months old
Breed? e.g. Dobermanns with von Willebrand’s disease
Gender? e.g. haemophilia is X-linked so males only
Any previous trauma / surgery / toxins / drugs?
Any relatives with bleeding signs?
What are the clinical signs of primary haemostatic diseases?
Multiple minor bleeds
Prolonged bleeding
Petechiae (small bruises) and ecchymotic haemorrhages (larger bruises)
Venepuncture/surface bleeding e.g. MMs, skin
Epistaxis
What are the clinical signs of secondary haemostatic diseases?
Single large bleeds
Rebleeding
Haematomas
No complications with venepuncture
Deep and cavity bleeds - joints/abdo/thoracic
Epistaxis
How should we carry out blood testing in patients with suspected bleeding disorders?
Collect samples before treating
Atraumatic blood collection
Correct ratio of sodium citrate to blood in tube
How do we test for primary haemostasis?
Platelet count
Buccal mucosal bleeding time (BMBT)
vWF testing (sodium citrate)
How do we test for secondary haemostasis?
Activated clotting time (ACT)
Activated partial thromboplastin time (APTT)
Prothrombin time (PT)
