Venous thromboembolism during pregnancy and the post-partum period: incidence and risk factors in a large Victorian health service.

BACKGROUND There is a strong recommendation for post-partum thromboprophylaxis following emergency caesarean sections, particularly in overweight women, and following prolonged labour. AIMS To analyse the incidence and epidemiological factors associated with antepartum and post-partum venous thromboembolism in a large Victorian health service. METHODS A retrospective study of all 6987 women delivering at Ballarat Health Services between March 1999 and June 2006. Case notes of women with confirmed venous thromboembolism during this period were subjected to detailed analysis. The data were analysed for possible risk factors, the timing of thromboembolism in relation to the pregnancy and any correlation with thromboprophylaxis, if administered. RESULTS The rate of venous thromboembolism was 1.14 per 1000 deliveries, with risk factors of age > 30 (100%), obesity (75%), previous history of thromboembolism (62.5%) and caesarean section (37.5%). Majority of cases were diagnosed in first trimester (62.5%), and in the right lower limb (75%). None of the patients had been given thromboprophylaxis. CONCLUSION While the incidence and risk factors were similar to those generally quoted, a much higher incidence was found in early pregnancy, and in the right lower limb. The importance of meticulous screening for risk factors in early pregnancy cannot be overemphasised.