Chapter 24

INTRODUCTION

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.

COAGULATION TESTS

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

Platelets

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

Prothrombin Time

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

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 (Table 24-1). TEG is a ...

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