obstetric haemorrhage Flashcards
what is the definition of primary post partum haemorrhage?
loss of 500ml or more of blood from the genial that within 24 hours of the birth of the baby
minor = 500-1000ml
major = >1000ml (moderate 1000-2000ml, severe >2000ml)
what is the definition of secondary post partum haemorrhage?
abnormal or excessive bleeding from the birth canal between 24hrs and 12weeks postnatally
what physiological changes occur in pregnancy of blood volume?
large increase from 70ml/kg to 100ml/kg
plasma volume increases 40-50%
red cell mass increases 20-30% (produces dilution anaemia)
what are the benefits of increasing blood volume in pregnancy?
facilitates maternal and fetal exchange of respiratory gases, nutrients and metabolites
reduces the impact of maternal blood loss at delivery (average blood loss 300-500ml for vaginal births)(average for Caesarean sections is 750ml) compensation with “autotransfusion” of blood by contracting the uterus
why is pregnancy a hyper-coagulable state?
decrease in fibrinolytic activity (to prevent excessive bleeding at delivery) fibrinogen is increased clotting factors increased patelets number rises d-dimer levels are elevated
how does the clotting process normally work?
injury -> primary haemostasis = vasoconstriction (immediately), platelet adhesion (seconds), platelet aggregation (minutes) formation of white blood clot or platelet plug -> secondary haemostasis = activation of coagulation factors, formation of fibrin(minutes) , formation of stable red blood clot -> fibrinolysis = activation of fibrinolysis (minutes), lysis of clot
what physiology compensation occurs during haemorrhage?
HR increases
heart beats more forcefully
blood vessels become constricted (increased PVR)
body secretes less urine so body loses less fluids
compensation occurs late as young fit patients compensate well
what are the 4 causes of obstetric haemorrhage?
tone = abnormalities of uterine contraction tissue = retained products of conception trauma = tears or genital tract thrombin = abnormalities of coagulation
what are the risk factors for having a atonic bleed?
prolonged labour
over distended uterus = twins, large baby, polyhydramnios
caused by abnormal uterine contraction
what are the causes of tissue haemorrhage?
retained placenta
retained products of conception
placenta praaevia
morbidly adherent placenta (accrete, intreat, percreta)
what are the trauma causes of haemorrhage?
uterine trauma = inverted uterus, ruptured uterus, surgical damage
genital tract trauma = vaginal tears 1st-4th degree
what are the causes of thrombin haemorrhage?
acquired coagulopathy in pregnancy = sepsis, pre-eclampsia, abruption, HELLP syndrome, retained dead fetus, DIC, AFLP platelet abnormalities = gestational thrombocytopenia, idiopathic thrombocytopenia purpura, HELLP, sepsis, DIC
what equipment is available to help treat obstetric haemorrhage?
rapid infuser
red cell salvage
point of care testing
what pharmacological agents are used to treat obstetric haemorrhage?
syntocinon IV ergometrine IV/IM carboprost IM misoprostol PR tranexamic acid
how does tranexamic acid work?
reduces fibrinolysis
