Clotting, DIC and VTE Flashcards
Haemostasis
Is the body’s normal physiological response for the prevention and stopping of bleeding/haemorrhage
Three mechanisms of haemostasis
- Constriction of blood vessels (vasoconstriction to reduce blood flow)
- Aggregation of platelets (formation of a plug)
- Blood clotting (coagulation of blood)
What plugs broken vessels?
Collagen interacts with platelets causing them to stick together and plug a broken vessel.
What does fibrin do?
Is a protein and strengthens the platelet plug causing them to strengthen
Different coagulation pathways
Extrinsic = chemicals released by cell damage. Is outside circulation and has a fast response Intrinsic = Inner vessels damaged within the circulation. Is a slower response
Changes to the haemostatic system in pregnancy
- Cardiac output increased by 40% - Blood plasma increased by 50% - Rise in RBC in last two trimesters - Hypercoagulability to protect against blood loss at delivery
What is DIC?
Is an acquired disorder of haemostasis which often heralds the onset of multiple organ failure. Always secondary to another condition in obstetrics. There’s lots of little clots produced by the body leading to organ failure. The women then can’t clot because they have used up all their clotting factors
Incidence of DIC
Less than 1:1000 pregnancies
Coagulation failure in pregnancy
- Endothelial damage causes release of thromboplastins from damaged cells into the maternal circulation - causing the intrinsic pathway
- Extrinsic pathway is triggered by activating a coagulation cascade e.g. bleeding from placental site or perineal wound
- If tissue damage is so severe then clotting occurs at the site of the epithelial damage and throughout the vascular system
- This process uses large quantities of clotting factors, platelets and fibrinogen
- Some small bloos vessels can be occluded by micro thrombi which can lead to organ failure
- The damage tissue within the organs also initiates more clotting which makes the situation worse
- Eventually all the clotting factors are used up and bleeding occurs
- Ironic situation that bleeding cannot be stopped as thee is a clotting deficiency despite widespread clotting
- Petechiae develops, bleeding from GI tract
- If untreated, death from haemorrhage
What is petechiae?
Pinpoint, flat, round, red spots under the skin surface caused by intradermal haemorrhage
Causes/triggers in obstetrics to DIC
- Major placental abruption
- Major hamorrhage
- Pre-eclampsia/eclampsia
- IUD, missed abortion or
trophoblastic disease - Amniotic fluid embolism
- Ruptured uterus
- Sepsis
- HELLP
Complications of DIC
- Renal failure and anuria
- Liver failure and jaundice
- Dyspnoea and cyanosis
- Convulsions/coma/brain injury
- Retinal damage; reduced sight
and blindness - Pituitary
- Death due to hypovolemia
Management of DIC
- Repeat and check coagulation screen - Evacuation of uterus if RPC - Close liaison with haematologist and blood bank - All blood loss measured and clearly documented - Postnatal observations; 1 to 1 care - Attention/observations to all wound and cannulation sites for signs of bleeding - Assist mother when well to NNU - Obstetric postnatal review; debrief; counselling for future
What is the leading cause of direct maternal death?
Venous thromboembolism
MBRRACE (2018)
What did the latest MBRRACE (2018) report show?
- 50% of deaths were antenatal
- 50% of postnatal deaths
delivered by CS - 17% of deaths had no risk
factors - 53% were obese
- 54% may have benefitted
from improvements in care - 52% were not compliant with
RCOG recommendations
