Venous thromboembolism in obese mother

38.1

Introduction

Venous thromboembolism (VTE) is the leading cause of direct maternal deaths in the United Kingdom. Obesity is a significant contributory factor for VTE in pregnancy and the risk increases by fourfold when compared with women of normal BMI.

• Recent evidence has shown obesity as an important contributory factor for inappropriate dosage of low-molecular-weight heparin for thromboprophylaxis or VTE treatment as the dosage is mainly weight-based.

• With increasing weight, exact dosing may be a challenge to assess.

• The classification of overweight and obesity according to the National Institute of Clinical Excellence is:

  • o

    Obesity I—BMI 30–34.9 kg/m ²

  • o

    Obesity II—BMI 35–39.9 kg/m ²

  • o

    Obesity III—BMI 40 kg/m ² or more.

38.2

Pathophysiology

• Physiological increase in coagulation factors VIII, IX, X and fibrinogen with simultaneous decreased antifibrinolytic activity.

• Anatomical changes caused by the gravid uterus favours venous stasis and marked reduction in the usual blood flow in the lower limbs.

• Obesity causes exacerbation of the inflammatory changes causing further increase in coagulation factors, prothrombin and fibrinogen levels, increased levels of plasminogen activator inhibitor Type I.

• Exaggerated proinflammatory environment which increases endothelial dysfunction and oxidative stress, which in turn exacerbates the risk factors for VTE.

• Increased maternal abdominal adiposity associated with obesity further restricts venous return and also increases intraabdominal pressure especially during the intrapartum period.

38.3

Other contributory factors

• Increased risk of preeclampsia which further increases risk of VTE.

• Increased risk of interventions during pregnancy and delivery including failed inductions, operative delivery, and prolonged labour further multiplies the risk of VTE.

• Increased risk of sepsis associated with obesity further increases risk of VTE.

• Risk of reduced mobility associated with obesity during pregnancy can increase risk of VTE.

38.4

Symptoms of venous thromboembolism