Thrombosis and pregnancy

Ten women die from thrombosis in pregnancy every year in the UK. Thromboembolism is the leading cause of maternal mortality in the UK with 25 deaths from pulmonary embolus and 5 deaths from cerebral vein thrombosis reported in the most recent Confidential Enquiry into Maternal Deaths (CEMD) 2000-2002. Substandard care was identified in over 50% of cases. Pregnancy itself is a procoagulant state, there is a 6- to 10-fold increase in the risk of venous thromboembolism compared to the non-pregnant situation. This risk is increased further in some women because of pre-existing (e.g. age >35, obesity, previous venous thromboembolism, medical conditions) or transient pregnancy-related additional risk factors (e.g. hyperemesis, pre-eclampsia, prolonged labour, excessive blood loss). Risk assessment for venous thromboembolism during the pregnancy should be undertaken, ideally prior to pregnancy or early in the first trimester and this assessment should be repeated subsequently if the woman is admitted to hospital, or develops antecedent problems. The use of appropriate thromboprophylaxis throughout the antenatal period and following delivery whether by caesarean section or vaginal delivery must be considered in the context of these risk factors. The most important aspect of substandard care in the most recent CEMD was the failure to recognise these risk factors. The diagnosis of acute venous thromboembolism using diagnostic imaging and prompt treatment with adequate dosages of anticoagulation are key issues in the subsequent prevention of maternal morbidity and mortality.