COAGULATION IN PREGNANCY

Plasma levels of fibrinogen and all clotting factors, except
XI and XIII, gradually increase during pregnancy inducing
a hypercoagulable state. An increase in fibrinolysis is
reflected in increased concentrations of antithrombin III,
plasminogen, and fibrin degradation products. Platelet
activity and consumption are both increased but platelet
function remains normal in pregnancy. None of these
changes are reflected in a routine clotting screen, which
will show values around normal. Platelet function, as
assessed by thromboelastography, remains normal while
the platelet count is greater than 100 x 10
9
per litre. A
platelet count of greater than 80 x 10
9
per litre is regarded
as safe for the use of neuroaxial blockade by many.
Thromboembolic complications remain a common source
of morbidity and mortality associated with pregnancy