Thrombotic Disease & Placental Disorders Flashcards
define haemostasis
balance between coagulation and haemorrhage
what is the breakdown of a clot called?
Fibrinolysis
Where are platelets produced and what cells produce them?
produced in bone marrow by megakaryocytes
what is in the buffy coat?
leukocytes and platelets
platelet lifespan?
10 days
what does vascular injury near sub epithelium cause?
direct activation of glycoprotein factors (collagen) and indirect via von Willebrand factor which attract platelets
what chemical do attracted platelets release and what does this cause?
thromboxane A2 (prostaglandin) released which attracts more platelets
what factors prevent platelet activation and when are these higher?
prostacyclin and nitrous oxide, higher in preg
define the intrinsic pathway
activated as direct result of blood vessel damage by tissue factor contacting clot producing proteins
describe extrinsic pathway
activated due to organ damage, hypoxia, sepsis, malignancy and inflammation
what is both intrinsic and extrinsic common pathway initiated by?
factor XA (10A)
how many molecules of thrombin activated from one factor XA molecule?
1000 molecules of thrombin
what does expansion of blood vol and change in haemostatic system in normal pregnancy cause?
hypercoagulability and hypofibrinolysis (reduced degradation of clot)
when is von Willebrand factor upregulated?
in pregnancy and after pregnancy (reduce PPH)
where is tissue factor produced and expressed?
produced in placenta and decidua, expressed in STB
what is tissue factor essential for?
implantation, embryogenesis, angiogenesis
list pregnancy factors that increase the risk of thrombosis
increase venous distension, decreased venous outflow, mechanical obstruction by uterus, decreased mobility, vascular injury
how much is thrombosis increased in preg?
4-5 times
once a clot has formed and fibrinolysis begins, what is produced as a byproduct?
D dimer
what inhibits degradation of a clot?
plasminogen activator inhibitor 1 and 2
describe gestational thrombocytopenia
reduced platelets increasing risk of bleeding, bruising and abnormal clotting
describe idiopathic thrombocytopenia parpura
Autoimmune disease where immune system attacks and destroys platelets, glucocorticoids used in T3, affects fetus as 5-10% risk of fetal thrombo
how many women experience thrombocytopenia in pregnancy?
1/10
describe antiphospholipid syndrome and how to diagnose
mat produces antibodies to phospholipids, diagnosed after med-high levels of antibodies on 2-3 occasions, increases clots
what outcomes increase with placenta accreta?
thrombosis and APH/PPH
define placental abruption
complete or partial separation of placenta before birth
CS or VE after placental abruption?
VE associated with less blood loss
