The management of pregnant women with hematologic disorders or coagulopathy requires a multidisciplinary approach involving hematologists, obstetricians, anesthesiologists, and possibly blood banks. Management of these patients requires the recognition of intrinsic or acquired hematologic disease in pregnancy, knowledge of the pharmacokinetics of antithrombotic medication, and an individualized approach to prevention of blood loss and use of blood products, if necessary, in the peripartum period.
The evaluation of coagulation test results during pregnancy must be in the context that pregnancy is associated with hypercoagulable changes (Table 24-1).
Table 24-1.Interpretation of Abnormal Coagulation Tests in Pregnancy ||Download (.pdf) Table 24-1. Interpretation of Abnormal Coagulation Tests in Pregnancy
|Range in Pregnancy Compared to Nonpregnancy
|Normal to decreased (100-150 × 109/L)
|Decreased (< 70 × 109/L)
|HELLP, preeclampsia, disseminated intravascular coagulation, idiopathic thrombocytopenic purpura
|Shortened (11-13 s)
|Deficiency in factors II, V, VII, X, or fibrinogen; nutritional/liver disease
|Activated partial thromboplastin time
|Shortened (23-37 s)
|Deficiency in factors VIII, IX, XI, or XII; heparin, antiphospholipid syndrome (false positive)
Maximum amplitude increased (range undefined)
Reaction time shortened range undefined
Maximum amplitude decreased
Reaction time prolonged
Platelet or fibrinogen dysfunction, antiplatelet (eg, Plavix)
Factor deficiency, warfarin
Platelet counts decrease in normal pregnancy due to enhanced turnover and hemodilution from plasma volume expansion. The American Society of Anesthesiologists (ASA) does not recommend obtaining a platelet count prior to neuraxial blockade in healthy parturients with no bleeding risk.1,2 However, in some at risk patients, a platelet count of less than 70 × 109/L may be indicative of disease such as hemolysis, elevated liver enzymes, low platelet (HELLP) syndrome, disseminated intravascular coagulation (DIC), or immune thrombocytopenic purpura (ITP).2
The PT and its derived measure, international normalized ratio (INR), evaluate the function of coagulation factors II, V, VII, X, and fibrinogen.2 Prothrombin time (PT) is shortened during pregnancy because of a hormone-related increase in procoagulant factors.2
Activated Partial Thromboplastin Time
Activated partial thromboplastin time (aPTT) evaluates the function of coagulation factors VIII, IX, XI, and XII. The effect of unfractionated heparin can prolong aPTT. A patient with antiphospholipid syndrome and antiphospholipid antibody can have a prolonged aPTT, which represents a false positive test in this prothrombotic subset of patients.2
Thromboelastography (TEG) is a bedside test of global coagulation and fibrinolysis. Maximum amplitude is reflective of clot strength and is decreased if platelet function or fibrinogen activity is decreased. The reaction time is prolonged in the setting of a clotting factor deficiency ...