Maternal Morbidity - Venous Thromboembolic Disease Resources

Pregnant women have a fourfold to fivefold increased risk of thromboembolism compared with nonpregnant women (1, 2). Approximately 80% of thromboembolic events in pregnancy are venous (3), with a prevalence of 0.5–2.0 per 1,000 pregnant women (4–9). Venous thromboembolism, including pulmonary embolism, accounts for 1.1 deaths per 100,000 deliveries (3), or 9 % of all maternal deaths in the United States (10). In the developing world, the leading cause of maternal death is hemorrhage (11); however, in developed nations, where hemorrhage is more often successfully treated and prevented, thromboembolic disease is one of the leading causes of death (12). The prevalence and severity of this condition during pregnancy and the peripartum period warrant special consideration of management and therapy. Such therapy includes the treatment of acute thrombotic events and prophylaxis for those at increased risk of thrombotic events. The purpose of this document is to provide information regarding the risk factors, diagnosis, management, and prevention of thromboembolism, particularly venous thromboembolism in pregnancy.

This article discusses the management of venous thromboembolism (VTE) and thrombophilia, as well as the use of antithrombotic agents, during pregnancy and is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that benefits do, or do not, outweigh risks, burden, and costs. Grade 2 recommendations are weaker and imply that the magnitude of the benefits and risks, burden, and costs are less certain. Support for recommendations may come from high-quality, moderate-quality or low-quality studies; labeled, respectively, A, B, and C. Among the key recommendations in this chapter are the following: for pregnant women, in general, we recommend that vitamin K antagonists should be substituted with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1A], except perhaps in women with mechanical heart valves. For pregnant patients, we suggest LMWH over UFH for the prevention and treatment of VTE (Grade 2C). For pregnant women with acute VTE, we recommend that subcutaneous LMWH or UFH should be continued throughout pregnancy (Grade 1B) and suggest that anticoagulants should be continued for at least 6 weeks postpartum (for a total minimum duration of therapy of 6 months) [Grade 2C]. For pregnant patients with a single prior episode of VTE associated with a transient risk factor that is no longer present and no thrombophilia, we recommend clinical surveillance antepartum and anticoagulant prophylaxis postpartum (Grade 1C). For other pregnant women with a history of a single prior episode of VTE who are not receiving long-term anticoagulant therapy, we recommend one of the following, rather than routine care or full-dose anticoagulation: antepartum prophylactic LMWH/UFH or intermediate-dose LMWH/UFH or clinical surveillance throughout pregnancy plus postpartum anticoagulants (Grade 1C). For such patients with a higher risk thrombophilia, in addition to postpartum prophylaxis, we suggest antepartum prophylactic or intermediatedose LMWH or prophylactic or intermediate-dose UFH, rather than clinical surveillance (Grade 2C). We suggest that pregnant women with multiple episodes of VTE who are not receiving long-term anticoagulants receive antepartum prophylactic, intermediate-dose, or adjusted-dose LMWH or intermediate or adjusted-dose UFH, followed by postpartum anticoagulants (Grade 2C). For those pregnant women with prior VTE who are receiving long-term anticoagulants, we recommend LMWH or UFH throughout pregnancy (either adjusted-dose LMWH or UFH, 75% of adjusted-dose LMWH, or intermediate-dose LMWH) followed by resumption of long-term anticoagulants postpartum (Grade 1C). We suggest both antepartum and postpartum prophylaxis for pregnant women with no prior history of VTE but antithrombin deficiency (Grade 2C). For all other pregnant women with thrombophilia but no prior VTE, we suggest antepartum clinical surveillance or prophylactic LMWH or UFH, plus postpartum anticoagulants, rather than routine care (Grade 2C). For women with recurrent early pregnancy loss or unexplained late pregnancy loss, we recommend screening for antiphospholipid antibodies (APLAs) [Grade 1A]. For women with these pregnancy complications who test positive for APLAs and have no history of venous or arterial thrombosis, we recommend antepartum administration of prophylactic or intermediate-dose UFH or prophylactic LMWH combined with aspirin (Grade 1B). We recommend that the decision about anticoagulant management during pregnancy for pregnant women with mechanical heart valves include an assessment of additional risk factors for thromboembolism including valve type, position, and history of thromboembolism (Grade 1C). While patient values and preferences are important for all decisions regarding antithrombotic therapy in pregnancy, this is particularly so for women with mechanical heart valves. For these women, we recommend either adjusted-dose bid LMWH throughout pregnancy (Grade 1C), adjusted-dose UFH throughout pregnancy (Grade 1C), or one of these two regimens until the thirteenth week with warfarin substitution until close to delivery before restarting LMWH or UFH) [Grade 1C]. However, if a pregnant woman with a mechanical heart valve is judged to be at very high risk of thromboembolism and there are concerns about the efficacy and safety of LMWH or UFH as dosed above, we suggest vitamin K antagonists throughout pregnancy with replacement by UFH or LMWH close to delivery, after a thorough discussion of the potential risks and benefits of this approach (Grade 2C). (CHEST 2008; 133:844S–886S)

SMFM Poster OBJECTIVE: Describe pregnancy associated deep vein thrombosis (DVT) and pulmonary embolism (PE) by method of delivery, and evaluate its potential use as an indicator of healthcare quality. STUDY DESIGN: Using 2003 California discharge data, rates of DVT/PE were calculated for antepartum, delivery, and postpartum discharges at the hospital level. Criteria suggested by Agency for Healthcare Research and Quality was used to evaluate the potential for DVT/PE to be used as a measure of hospital quality-- importance, scientific acceptability, usability, and feasibility. RESULTS: There were 48,015 antepartum admissions, 525,354 delivery discharges, and 17,981 postpartum admissions. Amongst antepartum admissions, there were 139 (0.29%) DVT and 39 (0.12%) cases of PE. There were total of 222 (0.04%) women with delivery associated DVT (180) or PE (42). Women undergoing cesarean delivery were more likely to have DVT/PE as compared to women delivering vaginally (0.09% vs 0.03%)*. Postpartum admissions included 98 (0.55%) and 58 (0.32%) cases ofDVTand PE respectively, and were more common among patients with cesarean delivery (0.08% vs. 0.03%)*. The mean rate of DVT/PE for delivery or postpartum admissions by hospital was 0.08% (0% to 1.1%) with 45.5% of hospitals reporting no events. *p
0.0001 CONCLUSION: Women undergoing cesarean delivery are more likely to experience DVT/PE. DVT/PE is not a good quality indicator measure. Although clinically important (significant cause of maternal morbidity and mortality), and scientifically acceptable (prophylaxis could impact incidence), the prevalence is low. It is not usable as a measure of hospital quality of care as rates of DVT/PE do not vary significantly by hospital. It is feasible to monitor based on aggregate data reporting, but further validation is needed to determine the reliability of reporting.

Pulmonary embolism and deep-vein thrombosis are the two components of a single disease called venous thromboembolism. Approximately 30% of apparently isolated episodes of pulmonary embolism are associated with silent deep-vein thrombosis, and in patients presenting with symptoms of deep-vein thrombosis, the frequency of silent pulmonary embolism ranges from 40 to 50%.1,2 Venous thromboembolism is both more common and more complex to diagnose in patients who are pregnant than in those who are not pregnant. The incidence of venous thromboembolism is estimated at 0.76 to 1.72 per 1000 pregnancies, which is four times as great as the risk in the nonpregnant population.3,4 A meta-analysis showed that two thirds of cases of deep-vein thrombosis occurred in the antepartum period and were distributed relatively equally among all three trimesters.5 In contrast, 43 to 60% of pregnancy-related episodes of pulmonary embolism appear to occur in the puerperium.4,6,7 Pulmonary embolism is the leading cause of maternal death in the developed world. Current estimates of deaths from pulmonary embolism are 1.1 to 1.5 per 100,000 deliveries in the United States and Europe.4,8,9 In the United Kingdom, venous thromboembolism accounts for one third of all maternal deaths.8,9 Delayed diagnosis, delayed or inadequate treatment, and inadequate thromboprophylaxis account for many of the deaths due to venous thromboembolism.8,9 Successful strategies for the management of venous thromboembolism in nonpregnant patients have been established. However, many of the recommendations for the treatment of pregnant patients who have venous thromboembolism are not based on high-quality data; rather, they are derived from observational studies and extrapolation from studies involving nonpregnant patients. The purpose of this review is to provide a practical approach to the diagnosis, management, and prevention of venous thromboembolism in pregnant patients.