Changes in the haemostatic system during pregnancy and the local activation of the clotting system at parturition carry a risk not only of thromboembolism, but also of DIC, consumption of clotting factors and platelets, leading to severe bleeding. One of the problems with DIC is its definition. It is always secondary to some general stimulation of the coagulation system. Table 1 shows the DIC trigger mechanisms. DIC is manifested in several forms, from a compensated state with no clinical manifestations, but evidence ofincreased production and breakdown of coagulation factors to the condition of massive uncontrollable haemorrhage with very low levels of plasma fibrino-gen, raised levels of fibrin degradation products (FDPs), and variable degrees of thrombocytopaenia. Fibrinolysis is stimulated by DIC, and
Table 1. Trigger Mechanisms for DIC in Pregnancy
Abruptio placenta Amniotic fluid embolism Retained dead foetus Abortion induced with hypertonic fluids Intrauterine sepsis Placenta accreta Hydatidiform mole
Intravascular haemolysis Incompatible blood transfusion Large foeto-maternal bleed Septicaemia
Xlla XIa IXa
Xlla XIa IXa
Xa V IIa
FDPs resulting from the process interfere with the formation of firm fibrin clots. A vicious cycle is established, leading to further bleeding.
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