Coagulation Disorder in Obstetrics

Coagulation Disorder in Obstetrics: Hemostasis is the process by which a leak in the vascular system is rapidly repaired by vascular responses, platelet interaction and the coagulation system. In some situations, vascular response takes a precedence while in others platelet interaction does so. In the arterioles and venules, both are important.
Clotting is aided by the coagulation factors present in the circulatory system, the interplay of which is shown in the figure below.
Fibrin formation is essential for hemostasis and the plasma concentration of fibrinogen itself is found to be increased during pregnancy. Besides fibrinogen, factors II, VII, VIII, IX and X are also considerably raised, whereas factor XIII is reduced.
The actual number of platelets are unaltered or somewhat lowered in pregnancy. Tests of hemostatic functions such as clotting time and bleeding time give normal results in pregnancy.

In the normal course of events, the fibrin deposited in vivo is digested by a powerful fibrinolysin plasmin. Free circulating plasmin is not found in normal circulation and it needs the presence of a plasminogen activator.
In normal pregnancy, as it proceeds, there is an increase of fibrin formation and fibrinolysis and the level of available plasminogen activator is depressed in the later months.
Alteration of this coagulation pattern is found in conditions such as the premature separation of placenta, eclampsia of pregnancy, amniotic fluid embOlism, infected abortion, chorioamnionitis and intra-uterine fetal death.

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