Pregnancy and venous thromboembolism: 'TIPPS' for risk stratification

[Women's experience following prophylactic low molecular weight heparin treatment post-cesarean section]

OBJECTIVE

To assess women's experiences with skin-related side effects following subcutaneous low molecular weight heparin (LMWH) injections after a cesarean section, and to analyze their impact on treatment adherence.

METHOD

A questionnaire was developed in collaboration with Cesarine, a patients' association, to explore various aspects of LMWH administration, including prevention methods, cutaneous side effects, treatment compliance, perceived constraints, apprehension, and understanding of treatment benefits. Additionally, women's opinions on an alternative oral administration approach were solicited, taking into consideration breastfeeding contraindication. The questionnaire was on the Facebook® page and blog of the association.

RESULTS

One hundred and sixty-four women participated in the survey. Among them, 139 women (84.8%) reported bruising, while 117 (71.3%) reported pruritus, erythema, or nodules at the injection site. Treatment discontinuation was observed in 36 cases (22%), decided mostly by the women themselves (77.8%). The main reasons cited for discontinuation were discomfort during injection (71.4%), skin reactions (31.4%), and a perceived lack of effectiveness (54.3%). Furthermore, 88 women (53.7%) wanted to quit the treatment prematurely, citing similar reasons. Thirty-three women (20.1%) reported oversights. For most women, the treatment was perceived as burdensome and caused apprehension. An alternative oral administration method was of interest to 131 women (79.9%). However, only 28 (17.8%) would have accepted if the medication was incompatible with breastfeeding.

CONCLUSION

Cutaneous side effects of LMWH injections, as well as injection process itself, have a negative impact on adherence in the postpartum period following a c-section. These findings highlight the need to explore alternative to improve women's compliance and comfort.

Venous Thromboembolism in Pregnancy: A Review of Diagnosis, Management, and Prevention

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism, is a leading cause of maternal morbidity and mortality worldwide. Physiological changes that occur in a normal pregnancy increase the risk for VTE by 4-5-fold in the antepartum period and 30-60-fold in the immediate postpartum period. Compressive ultrasonography is the diagnostic test of choice for deep vein thrombosis. Both ventilation/perfusion scanning and computed tomography pulmonary angiography can reliably diagnose pulmonary embolism. Anticoagulation for a minimum of 3 months, typically with low molecular weight heparin, is the treatment of choice for pregnancy-associated VTE (PA-VTE). Despite the significant societal burden and potentially devastating consequences, there is a paucity of data surrounding the prevention of PA-VTE, resulting in major variations between international guidelines. This review will summarize the current recommendations for diagnosis, management, and prevention of PA-VTE.

A More Selective vs a Standard Risk-Stratified, Heparin-Based, Obstetric Thromboprophylaxis Protocol

Importance

In 2016, our institution adopted a pregnancy-related venous thromboembolism (VTE) prophylaxis protocol based on American College of Obstetricians and Gynecologists guidelines that recommended postpartum heparin-based chemoprophylaxis (enoxaparin) based on a risk-stratified algorithm. In response to increased wound hematomas without significant reduction in VTE using this protocol, a more selective risk-stratified approach was adopted in 2021.

Objective

To evaluate outcomes of the more selective risk-stratified approach to heparin-based obstetric thromboprophylaxis (enoxaparin) protocol.

Design, Setting, and Participants

Retrospective observational study of 17 489 patients who delivered at a single tertiary care center in the southeast US between January 1, 2016, and December 31, 2018 (original protocol), and between December 1, 2021, and May 31, 2023 (more selective protocol). Patients receiving outpatient anticoagulation for active VTE or high VTE risk during pregnancy were excluded.

Exposure

Standard risk-stratified and more selective postpartum VTE chemoprophylaxis protocols.

Main Outcomes and Measures

The primary outcome was clinical diagnosis of wound hematoma up to 6 weeks pos tpartum. The secondary outcome was new diagnosis of VTE up to 6 weeks post partum. We compared baseline characteristics and outcomes between groups and estimated adjusted odds ratios with 95% CIs of primary and secondary outcomes using the original protocol group as reference.

Results

Of 17 489 patients included in the analysis, 12 430 (71%) were in the original protocol group and 5029 (29%) were in the more selective group. Rates of chemoprophylaxis decreased from 16% (original protocol) to 8% (more selective protocol). Patients in the more selective group were more likely to be older, be married, and have obesity or other comorbidities (hypertension, diabetes, cardiac disease). Compared with the original protocol, the more selective protocol was associated with a decrease in any wound hematoma (0.7% vs 0.3%; adjusted odds ratio [aOR], 0.38; 95% CI, 0.21-0.67), specifically due to a lower rate of superficial wound hematomas (0.6% vs 0.3%; aOR, 0.43; 95% CI, 0.24-0.75). There was no significant increase in VTE or individual types of VTE (0.1% vs 0.1%; aOR, 0.40; 95% CI, 0.12-1.36).

Conclusions and Relevance

A more selective risk-stratified approach to an enoxaparin thromboprophylaxis protocol for VTE was associated with decreased rates of wound hematomas without increased rates of postpartum VTE.

VTE Risk Assessment and Prevention in Pregnancy

Venous thromboembolism (VTE) remains the leading cause of maternal mortality in pregnancy and the postpartum period. In addition to the higher pregnancy-associated baseline VTE risk, there are several well-established risk factors that can further increase the risk of VTE. At present, a thorough interrogation of these risk factors remains our only tool for estimating which pregnant people may be at an increased risk of VTE, and thus potentially benefit from thromboprophylaxis. However, an important knowledge gap still exists surrounding the duration of increased risk and the interaction of risk factors with each other. Furthermore, up to now, once significant risk has been established, prevention strategies have been largely based on expert opinion rather than high-quality data. Recent trials have successfully bridged a proportion of this knowledge gap; however, the challenge of conducting high-quality clinical trials with pregnant people remains. In this article, we provide an update on the recent evidence surrounding VTE risk factors in pregnancy while concurrently outlining knowledge gaps and current approaches to VTE prevention.

VTE risk assessment, prevention and diagnosis in pregnancy

Venous thromboembolism (VTE) is still reported as the leading cause of direct maternal death in pregnancy in serial international reports in developed countries. VTE risk is higher during pregnancy but is further increased by additional well-characterized risk factors. International guidelines recommend that formal VTE risk assessment should be conducted at least in early pregnancy, at delivery and when risk factors change. High quality data supporting optimal VTE prevention strategies are lacking, outside the setting of prevention of VTE recurrence. Moreover, recent high-quality studies have provided much-needed data on diagnostic strategies for pulmonary embolism (PE) in pregnancy. In this review, we summarize knowledge gaps and recently published data in the prevention and diagnosis of VTE in pregnancy. Moreover, we describe ongoing high-quality randomised trials and prospective clinical management studies in this area. High quality clinical studies and trials in pregnancy can be done and must be prioritised, through international network efforts and national funding advocacy. Ultimately, translation of study results to impact upon guidelines and policy will deliver better care to and will protect the lives and health of pregnant people and those contemplating pregnancy throughout the world.

Prevention, diagnosis, and management of PE and DVT in pregnant women

Venous thromboembolism (VTE) is a leading cause of maternal morbidity and mortality worldwide. Despite the impact of VTE on pregnant and postpartum people and on society, guidelines addressing prevention, diagnosis, and management of VTE in pregnant and postpartum people frequently are based on recommendations from expert opinion and are extrapolated from data in nonpregnant populations. Pregnant individuals are frequently excluded from clinical trials, which is a barrier to providing safe, effective care. Anchoring to a case discussion, this review provides an update on recently published and ongoing randomized clinical trials (RCTs), prospective clinical management studies, and other research in this area. It highlights, in particular, the results of the Highlow RCT, which addresses optimal prevention of recurrence during pregnancy in people with prior VTE. Finally, we raise awareness of the impact of national and international clinical trial networks on the conduct of RCTs in pregnancy. We conclude, based on these data, that academic VTE clinical trials in pregnant women can and must be done.

Season of delivery and risk of venous thromboembolism during hospitalization among pregnant women

Background

Seasons were found to be related to the occurrences of venous thromboembolism (VTE) in hospitalized patients. No previous study has explored whether seasons were associated with VTE risk in pregnant women. This study aimed to investigate the relationships between the season of delivery and VTE risk during hospitalization among pregnant women.

Methods

This is a multi-center retrospective cohort study of pregnant women. Participants were those who delivered at seven designated sites in Hubei Province, China, during the period from January 2017 to December 2022. They were categorized according to their season/month of delivery. Information on new-onset VTE during hospitalization was followed.

Results

Approximately 0.28% (104/37,778) of the pregnant women developed new-onset VTE during hospitalization for delivery. After adjustment, compared with participants in the spring group, participants in the summer, autumn, and winter groups had an increased risk of VTE during hospitalization. The ORs were 2.59 [1.30, 5.15], 2.83 [1.43, 5.60], and 2.35 [1.17, 4.75] for the summer, autumn, and winter groups, respectively. Pregnant women in the combined group (summer + autumn + winter) had an increased risk of VTE during hospitalization than those in the spring group (OR, 2.59 [1.39, 4.85]). By restricting the analyses among pregnant women without in vitro fertilization, gestational diabetes mellitus, and preterm, the results still remained robust. Compared with participants who delivered in March, April, and May, participants who delivered in June, July, September, November, December, and February had a higher risk of VTE during hospitalization.

Conclusion

This study demonstrated that pregnant women who delivered in summer, autumn, and winter had an increased VTE risk during hospitalization compared with those who delivered in spring.

Venous Thromboembolism Risk Assessment Models in Obstetrics: A Review of Current Practices and Future Directions

Pregnancy is a major risk factor for venous thromboembolism (VTE) and its associated complications. The hypercoagulable state in both the antenatal and postnatal periods contributes to thromboembolism and continues to be a leading cause of maternal morbidity and mortality worldwide. The non-specific signs and symptoms of VTE in pregnancy and the lack of specific Risk Assessment Models (RAMs) propose a diagnostic challenge in the obstetric population. This review aims to discuss and compare existing RAMs and highlights the important challenges of using established RAMs in obstetric patients. It also emphasizes the importance of enhancing and individualizing RAMs in obstetrics to improve maternal healthcare. KEY POINTS: · VTE is a major complication of pregnancy, associated with increased maternal morbidity and mortality.. · VTE RAMs lack sensitivity and specificity in stratifying VTE risk in pregnancy.. · Validating VTE RAMs in the obstetric population aims to improve maternal outcomes..

Risk stratification for pregnancy-associated venous thromboembolism: Potential role for global coagulation assays

Risk assessment for venous thromboembolism in pregnancy and the puerperium is currently limited to stratifying clinical surrogate risk factors without high-quality evidence. While the absolute risk of pregnancy-associated venous thromboembolism is low for the vast majority of women, associated morbidity and mortality remains significant. As guidelines for thromboprophylaxis vary widely, some women may be under- or over-anticoagulated, contributing to poor outcomes. New global coagulation assays provide a holistic view of coagulation and may have the potential to detect hypercoagulability in pregnancy, unlike clinically available coagulation assays. However, there are major technical challenges to overcome before global coagulation assays can be realistically proposed as an adjunct to risk assessment for pregnancy-associated venous thromboembolism. This review summarises the literature and controversies in the prediction and prevention of pregnancy-associated venous thromboembolism and outlines the new tools in haematology that may assist in our future understanding of hypercoagulability in pregnancy.

Venous Thromboembolism During Pregnancy and the Postpartum Period: Risk Factors, Diagnostic Testing, and Treatment

Importance

The risk of venous thromboembolism (VTE) increases during pregnancy and the postpartum period. Deep vein thrombosis is the most common VTE during pregnancy, but pulmonary embolism is typically of greater concern as it contributes to far higher morbidity and mortality. Diagnosis and treatment of VTE during pregnancy differ substantially from the general nonpregnant population.

Objective

This review describes the epidemiology, risk factors, clinical presentation, diagnosis, and treatment of VTE during pregnancy and the postpartum period.

Evidence Acquisition

First, we reviewed the VTE guidelines from professional societies in obstetrics, cardiology, hematology, emergency medicine, pulmonology, and critical care. Second, we examined references from these documents and used PubMed to identify recent articles that cited the guidelines. Finally, we searched PubMed and Google Scholar for articles published since 2018 that included terms for pregnancy and the epidemiology, risk factors, diagnostic imaging, or treatment of VTE.

Results

Venous thromboembolism risk increases throughout pregnancy and peaks shortly after delivery. More than half of pregnancy-related VTE are associated with thrombophilia; other major risks include cesarean delivery, postpartum infection, and the combination of obesity with immobilization. Most VTE can be treated with low molecular weight heparin, but cases of limb- or life-threatening VTE require consideration of thrombolysis and other reperfusion therapies.

Conclusions and Relevance

Venous thromboembolism is far more frequent in antepartum and postpartum women than age-matched controls, and clinical suspicion for VTE in this population should incorporate pregnancy-specific risks. Treatment of limb- or life-threatening antepartum or postpartum VTE requires multispecialty coordination to optimize maternal and fetal outcomes.

Venous thromboembolism during pregnancy and postpartum period

Venous thromboembolism (VTE) is one of the leading causes of maternal mortality. Rates of VTE during pregnancy and the postpartum period have not decreased over the past two decades and pregnancyassociated VTE continues to pose a significant health challenge. Pregnant and postpartum women are at a higher risk for VTE owing to many factors. There are hormonally mediated and pregnancy-specific alterations of coagulation that favor thrombosis, including increased production of clotting factors. There are physiologic and anatomic mechanisms that also contribute, including a decreased rate of venous blood flow from the lower extemities as pregnancy progresses. Cesarean delivery also introduces VTE risk. In addition, studies have demonstrated that pregnancy-associated complications such as pre-eclampsia or peri-partum infections are associated with increased VTE rates. In this review, we discuss the recent epidemiological studies, pathogenesis, risk factors and clinical presentation as well as therapeutic options for VTE during pregnancy and the postpartum period. We also provide proposed diagnostic algorithms for diagnosis and management of VTE during pregnancy and the postpartum period based on updated evidence. Finally, we highlight knowledge gaps to guide future research.

Thrombophilia, Thrombosis and Thromboprophylaxis in Pregnancy: For What and in Whom?

Compared with nonpregnant women, pregnancy carries a four- to fivefold higher risk of venous thromboembolism (VTE). Despite increasing use of heparin prophylaxis in identified high-risk patients, pulmonary embolism still is the leading cause of maternal mortality in the western world. However, evidence on optimal use of thromboprophylaxis is scarce. Thrombophilia, the hereditary or acquired tendency to develop VTE, is also thought to be associated with complications in pregnancy, such as recurrent miscarriage and preeclampsia. In this review, the current evidence on optimal thromboprophylaxis in pregnancy is discussed, focusing primarily on VTE prevention strategies but also discussing the potential to prevent recurrent pregnancy complications with heparin in pregnant women with thrombophilia.

Varying Dosages of Subcutaneous Unfractionated Heparin and Activated Partial Thromboplastin Time in Hospitalized Antepartum Patients: A Retrospective Cohort Analysis

BACKGROUND

Venous thromboembolism (VTE) is a leading cause of maternal morbidity and mortality in the United States. Subcutanous unfractionated heparin (UFH) has been used for decades for VTE prophylaxis and under many obstetric quality of care initiatives, hospitalized antepartum patients now receive doses as high as 10,000 units every 12 hours. This practice increases the likelihood of UFH administration around the time that epidural labor analgesia is requested or neuraxial analgesia for cesarean delivery is needed. To clarify the effect of UFH on coagulation, we reviewed the care of hospitalized antepartum patients receiving VTE prophylaxis with UFH to determine the incidence of concurrent abnormal activated partial thromboplastin time (aPTT) values and associated risk factors.

METHODS

This retrospective cohort study used data from the University of Chicago Pharmacy database to identify hospitalized antepartum patients receiving subcutaneous UFH from June 1, 2016 to July 1, 2019. Our institutional protocol states that all patients hospitalized for antepartum conditions should receive pharmacologic prophylaxis empirically unless contraindicated. For patients receiving UFH, dosing was based on gestational age: 5000 units every 12 hours for first trimester antepartum patients, 7500 units every 12 hours for second trimester patients, and 10,000 units every 12 hours for patients in the third trimester. As per protocol, aPTT values were obtained 2 hours after the third dose of heparin, and platelet counts after 4 days. Data collection included demographics, comorbidities, heparin doses, aPTT values, platelet counts, creatinine if available, and anesthetic type and complications. Logistic regression was performed to determine the association between elevated aPTT >40 seconds and study variables.

RESULTS

Of the 321 antepartum patients who received subcutaneous UFH, 33 (10.3%) had an aPTT >40 seconds, 4 of those 33 patients (12.1%) received 5000 units every 12 hours, 14 (42.2%) received 7500 units every 12 hours, and 15 (45.5%) received 10,000 units every 12 hours. The likelihood of a patient having aPTT >40 seconds was 2.8% with 5000 units every 12 hours, 18.9% with 7500 units every 12 hours, and 14.6% with 10,000 units every 12 hours.

CONCLUSIONS

Elevated aPTT values are likely with total daily doses of 15,000 or 20,000 units subcutaneous UFH in hospitalized antepartum patients.

Comparison of doses of heparin for venous thromboembolism and bleeding in pregnant women

The evaluation criteria for dosage of low-molecular-weight heparin (LMWH) for pregnant women at high risk of venous thromboembolism (VTE) remain unclear. A retrospective study was performed to investigate the relative appropriate LMWH administration strategy and dosage for pregnant women at risk of VTE. 219 pregnant women with perinatal and postpartum VTE were reviewed and divided into group A (fixed dose group: n=73, 5000 IU dalteparin daily for all women), group B (weight group: n=73, 2500 IU dalteparin daily for women less than 50 kg; 5000 IU dalteparin daily for women more than 50 kg), and group C (anti-factor Xa (FXa) + weight group: n=73, 5000 IU once daily for women less than 50 kg; 7500 IU once daily for women weighing 50-80 kg; 10,000 IU once daily for women weighing over 80 kg). Further dose administration was adjusted according to peak anti-FXa level, maintaining the peak at the 0.5-1.0 IU/mL range. Women in group C presented lower incidence of VTE and other pregnancy complications than group A and group B. Adjusting the dosage of LMWH according to both weight and anti-FXa level of pregnant women not only prevented VTE but also reduced the risk of postpartum hemorrhage induced by LMWH administration. In addition, adjusting the dose of LMWH according to anti-FXa level and body weight also affected the recurrence of VTE and the occurrence of postpartum hemorrhage in pregnant women.

Prevention and management of venous thromboembolism in pregnancy: cutting through the practice variation

There is clinical practice variation in the area of prevention and management of venous thromboembolism (VTE) in pregnancy. There are limited data and differing recommendations across major clinical practice guidelines, especially relating to the role of postpartum low-molecular-weight heparin (LMWH) for patients with mild inherited thrombophilia and those with pregnancy-related VTE risk factors. This chapter explores the issues of practice variation and related data for postpartum VTE prevention. Controversial topics of VTE management in pregnancy are also reviewed and include LMWH dosing and the role of anti-Xa level monitoring, as well as peripartum anticoagulation management around labor and delivery.

Prophylaxis and management of venous thromboembolism during pregnancy and postpartum period

Introduction. Venous thromboembolism (VTE) is one of the lead causes for maternal mortality and morbidity during pregnancy in the majority of developed countries. The incidence rate of VTE per pregnancy-year increases during pregnancy and postpartum period about by 4-fold and at least 14-fold, respectively.

Aim: to analyze and summarize current view on risk factors of thrombotic events during gestation and to discuss recent guidelines for the management of venous thromboembolic complications during pregnancy and postpartum, by taking into account a balance between risks and benefits of using anticoagulants.

Materials and Methods. The literature search covering the last 10 years was carried out in the electronic scientific databases RSCI, PubMed/MEDLINE, and Embase. While formulating a search strategy for evidence-based information, the PICO method (P = Patient; I = Intervention; C = Comparison; O = Outcome) and the key terms “venous thromboembolism” and “pregnancy” were used.

Results. Risk factors were found to include a personal history of VTE, verified inherited or acquired thrombophilia, a family history of VTE and general medical conditions, such as immobilization, overweight, varicose veins, some hematological diseases and autoimmune disorders. VTE is considered being potentially preventable upon prophylactic administration of anticoagulants, but no high confidence randomized clinical trials comparing diverse strategies of thromboprophylaxis in pregnant women have been proposed so far. Because heparins do not cross the placenta, weight-adjusted therapeutic-dose low molecular weight heparins (LMWH) represent the anticoagulant treatment of choice for VTE during pregnancy. Once- and twice-daily dosing regimens are acceptable. However, no evidence suggesting benefits for measurement of factor Xa activities and consecutive LMWH dose adjustments to improve clinical outcomes are available. In case of uncomplicated pregnancy-related VTE, no routine administration of vitamin K antagonists, direct thrombin or factor Xa inhibitors, fondaparinux, or danaparoid is recommended. Lactating women may switch from applying LMWH to warfarin. Anticoagulation therapy should be continued for 6 weeks postpartum with total duration lasting at least for 3 months.

Conclusion. VTE is a challenging task in pregnant women expecting to apply a multi-faceted approach for its efficient solution by taking into account updated recommendations and personalized patient-oriented features.

A user guide to the American Society of Hematology clinical practice guidelines

Since November 2018, Blood Advances has published American Society of Hematology (ASH) clinical practice guidelines on venous thromboembolism, immune thrombocytopenia, and sickle cell disease. More ASH guidelines on these and other topics are forthcoming. These guidelines have been developed using consistent processes, methods, terminology, and presentation formats. In this article, we describe how patients, clinicians, policymakers, researchers, and others may use ASH guidelines and the many related derivates by describing how to interpret information and how to apply it to clinical decision-making. Also, by exploring how these documents are developed, we aim to clarify their limitations and possible inappropriate usage.

Which patients are at high risk of recurrent venous thromboembolism (deep vein thrombosis and pulmonary embolism)?

Recurrent venous thromboembolism (VTE, or deep vein thrombosis and pulmonary embolism) is associated with mortality and long-term morbidity. The circumstances in which an index VTE event occurred are crucial when personalized VTE recurrence risk is assessed. Patients who experience a VTE event in the setting of a transient major risk factor (such as surgery associated with general anesthesia for >30 minutes) are predicted to have a low VTE recurrence risk following discontinuation of anticoagulation, and limited-duration anticoagulation is generally recommended. In contrast, those patients whose VTE event occurred in the absence of risk factors or who have persistent risk factors have a higher VTE recurrence risk. Here, we review the literature surrounding VTE recurrence risk in a range of clinical conditions. We describe gender-specific risks, including VTE recurrence risk following hormone- and pregnancy-associated VTE events. Finally, we discuss how the competing impacts of VTE recurrence and bleeding have shaped international guideline recommendations.

Society of Family Planning clinical recommendations: Management of individuals with bleeding or thrombotic disorders undergoing abortion

Individuals who have bleeding disorders, thrombophilias, a history of venous thromboembolism (VTE), or who are taking anticoagulation medication for other reasons may present for abortion. Clinicians should be aware of risk factors and histories concerning for excessive bleeding and thrombotic disorders around the time of abortion. This document will focus on how to approach abortion planning in these individuals. For first-trimester abortion, procedural abortion (sometimes called surgical abortion) is generally preferred over medical management for individuals with bleeding disorders or who are on anticoagulation. First-trimester procedural abortion in an individual on anticoagulation can generally be done without interruption of anticoagulation. The decision to interrupt anticoagulation for a second-trimester procedure should be individualized. Individuals at high risk for VTE can be offered anticoagulation post-procedure. Individuals with bleeding disorders or who are anticoagulated can safely be offered progestin intrauterine devices. Future research is needed to better assess quantitative blood loss and complications rates with abortion in these populations.

How I treat venous thromboembolism in pregnancy

One to 2 pregnant women in 1000 will experience venous thromboembolism (VTE) during pregnancy or postpartum. Pulmonary embolism (PE) is a leading cause of maternal mortality, and deep vein thrombosis leads to maternal morbidity, with postthrombotic syndrome potentially diminishing quality of life for a woman's lifetime. However, the evidence base for pregnancy-related VTE management remains weak. Evidence-based guideline recommendations are often extrapolated from nonpregnant women and thus weak or conditional, resulting in wide variation of practice. In women with suspected PE, the pregnancy-adapted YEARS algorithm is safe and efficient, rendering computed tomographic pulmonary angiography to rule out PE unnecessary in 39%. Low molecular weight heparin (LMWH) in therapeutic doses is the treatment of choice during pregnancy, and anticoagulation (LMWH or vitamin K antagonists [VKAs]) should be continued until 6 weeks after delivery, with a 3-month minimum total duration. LMWH or VKA use does not preclude breastfeeding. Postpartum, direct oral anticoagulants are an option if a woman does not breastfeed and long-term use is intended. Management of delivery, including type of analgesia, requires a multidisciplinary approach and depends on local preferences and patient-specific conditions. Several options are possible, including waiting for spontaneous delivery with temporary LMWH interruption. Prophylaxis for recurrent VTE prevention in subsequent pregnancies is indicated in most women with a history of VTE.

Pulmonary Embolism in Pregnancy

Even though venous thromboembolism is a leading cause of maternal mortality in high-income countries, there are limited high-quality data to assist clinicians with the management of pulmonary embolism in this patient population. Diagnosis, prevention, and treatment of pregnancy-associated pulmonary embolism are complicated by the need to consider fetal, as well as maternal, well-being. Recent studies suggest that clinical prediction rules and D-dimer testing can reduce the need for diagnostic imaging in a subset of patients. Low-molecular-weight heparin is the preferred anticoagulant for both prophylaxis and treatment in this setting. Direct oral anticoagulants are contraindicated during pregnancy and in breastfeeding women. Thrombolysis or embolectomy should be considered for pregnant women with pulmonary embolism complicated by hemodynamic instability. Treatment of pregnancy-associated pulmonary embolism should be continued for at least 3 months, including 6 weeks postpartum. Management of anticoagulants at the time of delivery should involve a multidisciplinary individualized approach that uses shared decision making to take patient and caregiver values and preferences into account.

Which patients are at high risk of recurrent venous thromboembolism (deep vein thrombosis and pulmonary embolism)?

Recurrent venous thromboembolism (VTE, or deep vein thrombosis and pulmonary embolism) is associated with mortality and long-term morbidity. The circumstances in which an index VTE event occurred are crucial when personalized VTE recurrence risk is assessed. Patients who experience a VTE event in the setting of a transient major risk factor (such as surgery associated with general anesthesia for >30 minutes) are predicted to have a low VTE recurrence risk following discontinuation of anticoagulation, and limited-duration anticoagulation is generally recommended. In contrast, those patients whose VTE event occurred in the absence of risk factors or who have persistent risk factors have a higher VTE recurrence risk. Here, we review the literature surrounding VTE recurrence risk in a range of clinical conditions. We describe gender-specific risks, including VTE recurrence risk following hormone- and pregnancy-associated VTE events. Finally, we discuss how the competing impacts of VTE recurrence and bleeding have shaped international guideline recommendations.

A comparison of pregnancy-specific risk scoring systems for venous thromboembolic pharmacoprophylaxis in hospitalized maternity patients

OBJECTIVE

Venous thromboembolism (VTE) remains a leading cause of maternal mortality. The American College of Obstetricians and Gynecologists (ACOG) and the Royal College of Obstetricians & Gynecologists (RCOG) have proposed pregnancy-specific risk scoring guidelines for antepartum (AP) and postpartum (PP) thromboprophylaxis. We compared the impact of scoring thresholds and their potential preventative effect.

STUDY DESIGN

We conducted a retrospective cohort study of hospitalized maternity patients over a 4-month period. Patients were assigned an AP and PP risk score using each guideline. Hospitalization-associated VTE was accessed over a 6-year period. Comparison was by Fischer's exact and Chi Square tests.

RESULTS

638 women were included. Of AP patients, 20% met pharmacoprophylaxis criteria for baseline characteristics and 100% for length of stay using RCOG, and 12% met phrarmacoprophylaxis criteria using ACOG (p < .001). For PP patients, 53% met criteria for RCOG compared to 24% using ACOG (p < .001). If pharmacoprophylaxis were performed at a threshold 1 point above recommendation, 7% of AP patients and 11% of PP women would meet ACOG criteria. This increased ACOG threshold captured all cases of VTE following hospitalization.

CONCLUSION

In our population, using ACOG prophylaxis guidelines at an increased threshold would have potentially prevented all hospitalization related VTE without excessive anti-coagulation.

Society for Maternal-Fetal Medicine Consult Series #51: Thromboembolism prophylaxis for cesarean delivery

Venous thromboembolism is a major cause of maternal morbidity and mortality. The risk of venous thromboembolism is particularly elevated during the postpartum period and especially after cesarean delivery. There is considerable variation in the approach to prophylaxis of venous thromboembolism in pregnancy, including after cesarean delivery. This Consult discusses the different guidelines on prophylaxis of venous thromboembolism after cesarean delivery and provides recommendations based on the available evidence. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we recommend that all women who undergo cesarean delivery receive sequential compression devices starting before surgery and that the compression devices be used continuously until the patient is fully ambulatory (GRADE 1C); (2) we suggest that women with a previous personal history of deep venous thrombosis or pulmonary embolism who undergo cesarean delivery receive both mechanical (starting preoperatively and continuing until ambulatory) and pharmacologic (for 6 weeks postoperatively) prophylaxis (GRADE 2C); (3) we suggest that women with a personal history of an inherited thrombophilia (high-risk or low-risk) but no previous thrombosis who undergo cesarean delivery receive both mechanical (starting preoperatively and continuing until ambulatory) and pharmacologic (for 6 weeks postoperatively) prophylaxis (GRADE 2C); (4) we recommend the use of low-molecular-weight heparin as the preferred thromboprophylactic agent in pregnancy and the postpartum period (GRADE 1C); (5) when pharmacologic thromboprophylaxis is needed in pregnant women with class III obesity, we suggest the use of intermediate doses of enoxaparin (GRADE 2C); and (6) we recommend that each institution develop a patient safety bundle with an institutional protocol for venous thromboembolism prophylaxis among women who undergo cesarean delivery (Best Practice).

Obstetric venous thromboembolism: a one-year prospective study in a tertiary hospital in Egypt

BACKGROUND AND OBJECTIVE

Obstetric venous thromboembolism (VTE) poses a life-threating burden and it is one of the major causes of maternal morbidity and mortality with an increased incidence throughout the last decades. The objectives of this study were to assess the incidence of VTE, types of prophylaxis received, and factors determining prophylaxis in women at VTE risk during pregnancy and puerperium at a tertiary hospital for 1 year.

METHODS

This is a prospective study that was carried out at Minia maternity university hospital, Egypt during the period from June 2018 to June 2019. The study included women attended the hospital at risk of VTE as per the RCOG guidelines. Full history, patient characteristics, and VTE risk factors were assessed.

RESULTS

During the study period, a total of 901 women attended the hospital and perceived at risk of VTE (298 cases during pregnancy and 603 cases during puerperium), about half of them were mild in intensity. They comprise 8.22% of the total deliveries during the study period (n = 10,956). About two-thirds of them (71.5%) had a cesarean delivery. Varicose veins were found in 209 cases (23.2%), previous VTE in 189 cases (21.0%), previous superficial vein thrombosis was recorded in 240 cases (26.6%) and previous arterial ischemic events in 83 cases (9.2%). The vast majority of patients (99.6%) received the pharmacological type of prophylaxis (55.6% of them received unfractionated heparin and the rest of them 43.9% received Aspirin). Only six cases developed VTE from the total included cases with an incidence of 0.55/1000 maternities (0.055%). Obesity (BMI >30 kg/m²) and cesarean delivery were significant factors that determine VTE prophylaxis with an odds ratio of 1.68 (95% CI, 1.20-2.35, p < .01) and 2.05 (95% CI, 1.49-2.80, p < .01), respectively.

CONCLUSION

The incidence of women perceived at VTE risk was 8.22%, about half of them were mild in intensity. The risk of VTE was higher during the postpartum period than that during pregnancy. The incidence of VTE was 0.55/1000 overall maternities (0.055%). The pharmacological type of prophylaxis was the predominant used type. Obesity and cesarean delivery were significant factors determining VTE prophylaxis.

Preventing postpartum venous thromboembolism: A call to action to reduce undue maternal morbidity and mortality

Postpartum venous thromboembolism (VTE) is a leading cause of maternal mortality in developed countries and can carry significant long-term morbidity. Despite being able to identify postpartum VTE risk factors in a large proportion of the obstetrical population, there is little high-quality evidence available to guide practice on who should receive postpartum thromboprophylaxis. Based on epidemiological data, women with a prior history of VTE or known potent thrombophilia are likely to benefit from an extended duration of low-molecular-weight heparin (LMWH) prophylaxis. However, significant controversy exists around the benefit and harm of postpartum thromboprophylaxis in women with more modest risk factors, such as those with mild thrombophilias or transient situational risk factors around labor and delivery, such as cesarean delivery. We review the available data for postpartum VTE risk factors and thromboprophylaxis in these patients. This review highlights the latest evidence in the area of postpartum VTE prevention, and is a call to action for further research in this area to improve maternal morbidity and mortality.

Prevention of Postpartum Venous Thromboembolism

Importance

Postpartum venous thromboembolism (VTE) results in significant morbidity and mortality. The practicing obstetrician-gynecologist should have a plan for management and prevention.

Objective

The objective of this review is to familiarize obstetric providers with available evidence regarding postpartum VTE prevention and suggest a clinical practice guideline.

Evidence Acquisition

Published literature was retrieved through a search of PubMed and relevant review articles, original research articles, systematic reviews, and practice guidelines.

Results

Thromboembolic disease is one of the leading causes of maternal death in developed nations. Current evidence does not support universal postpartum VTE prophylaxis. Risk factor stratification is suggested to identify patients at high risk of VTE. Recent guidelines have recommended complex algorithms that are difficult to put into practice and have not been validated in the postpartum state. The American College of Obstetricians and Gynecologists has recommended that each institution develop a protocol to identify and treat women at high risk of postpartum VTE.

Conclusions and Relevance

Obstetric providers should be familiar with available evidence and best practice regarding postpartum VTE prevention. A suggested clinical practice guideline for the prevention of postpartum VTE is provided.

The risk and prevention of venous thromboembolism in the pregnant traveller

BACKGROUND

The average risk of venous thromboembolism (VTE) in long haul travellers is approximately 2.8 per 1000 travellers, which is increased in the presence of other VTE risk factors. In pregnant long-haul travellers, little is known in terms of the absolute risk of VTE in these women and, therefore, there is limited consensus on appropriate thromboprophylaxis in this setting.

OBJECTIVE

This review will provide guidance to allow practitioners to safely minimize the risk of travel-related VTE in pregnant women. The suggestions provided are based on limited data, extrapolated risk estimates of VTE in pregnant travellers and recommendations from published guidelines.

RESULTS

We found that the absolute VTE risk per flight appears to be <1% for the average pregnant or postpartum traveller. In pregnant travellers with a prior history of VTE, a potent thrombophilia or strong antepartum risk factors (e.g. combination of obesity and immobility), the risk of VTE with travel appears to be >1%. Postpartum, the risk of VTE with travel may be >1% for women with thrombophilias (particularly in those with a family history) and other transient risk factors and in women with a prior VTE.

CONCLUSIONS

Based on our findings, we recommend simple measures be taken by all pregnant travellers, such as frequent ambulation, hydration and calf exercises. In those at an intermediate risk, we suggest a consideration of 20-30 mmHg compression stockings. In the highest risk group, we suggest careful consideration for low-molecular-weight heparin thromboprophylaxis. If there are specific concerns, we advise consultation with a thrombosis expert at the nearest local centre.

How we manage Philadelphia-negative myeloproliferative neoplasms in pregnancy

The combined incidence of classical Philadelphia-negative myeloproliferative neoplasm (MPN) is 6-9/100 000 with a peak frequency between 50 and 70 years. MPN is less frequent in women of reproductive age. However, for essential thrombocythaemia (ET) in particular there is a second peak in women of reproductive age and 15% of polycythaemia vera (PV) patients are less than 40 years of age at the time of diagnosis. Thus these diseases are encountered in women of reproductive potential and may be diagnosed in pregnancy or in women being investigated for recurrent pregnancy loss. The incidence of MPN pregnancies is 3·2/100 000 maternities per year in the UK. The majority of data regarding Philadelphia-negative MPNs relates to patients with ET, for which the literature suggests significant maternal morbidity and poor fetal outcome; specifically maternal thrombosis and haemorrhage, miscarriage, pre-eclampsia, intrauterine growth restriction (IUGR), stillbirth and premature delivery as summarised in the recent systematic review and meta-analysis in Blood, 2018, 132, 3046. The literature for PV is more sparse but increasing and is concordant with ET pregnancy outcomes. The literature regarding primary myelofibrosis (PMF) is even more scarce. Treatment options include aspirin, venesection, low molecular weight heparin (LMWH) and cytoreductive therapy. Data and management recommendations are often extrapolated from other pro-thrombotic conditions or from ET to PV and PMF. Women of reproductive age with a diagnosis of MPN should receive information and assurance regarding management and outcome of future pregnancies. From pre-conceptual planning to the post-partum period, women should have access to joint care from an obstetrician with experience of high-risk pregnancies and a haematologist in a multidisciplinary setting. This paper provides an update with regards to Philadelphia-negative MPN in pregnancy, details local practise in an internationally recognised centre for patients with MPN and outlines a future research strategy.

VTE risk assessment in pregnancy

A State of the Art lecture, "VTE Risk Assessment in Pregnancy," was presented at the ISTH congress in Melbourne, Australia, in 2019. Venous thromboembolism (VTE) remains a leading cause of death in pregnancy and in the postpartum period. Moreover, VTE can result in lifelong disability. The elevated baseline pregnancy-associated VTE risk is further increased by additional maternal, pregnancy, and delivery characteristics, highlighting the importance of VTE risk assessment in early pregnancy, at delivery, and if risk factors change. This review will provide an overview of the impact and epidemiology of VTE in pregnancy (including reported risk factors for pregnancy-associated VTE), will address VTE risk-reduction strategies (including ongoing studies), and will provide a summary of critical knowledge gaps. Finally, throughout this review, relevant new data presented during the 2019 ISTH annual congress in Melbourne will be summarized.

American Society of Hematology 2018 guidelines for management of venous thromboembolism: venous thromboembolism in the context of pregnancy

BACKGROUND

Venous thromboembolism (VTE) complicates ∼1.2 of every 1000 deliveries. Despite these low absolute risks, pregnancy-associated VTE is a leading cause of maternal morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians and others in decisions about the prevention and management of pregnancy-associated VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

The panel agreed on 31 recommendations related to the treatment of VTE and superficial vein thrombosis, diagnosis of VTE, and thrombosis prophylaxis.

CONCLUSIONS

There was a strong recommendation for low-molecular-weight heparin (LWMH) over unfractionated heparin for acute VTE. Most recommendations were conditional, including those for either twice-per-day or once-per-day LMWH dosing for the treatment of acute VTE and initial outpatient therapy over hospital admission with low-risk acute VTE, as well as against routine anti-factor Xa (FXa) monitoring to guide dosing with LMWH for VTE treatment. There was a strong recommendation (low certainty in evidence) for antepartum anticoagulant prophylaxis with a history of unprovoked or hormonally associated VTE and a conditional recommendation against antepartum anticoagulant prophylaxis with prior VTE associated with a resolved nonhormonal provoking risk factor.

Effectiveness and safety of thromboprophylaxis with enoxaparin for prevention of pregnancy-associated venous thromboembolism

Essentials Thromboprophylaxis is offered to women considered to be at risk from pregnancy-associated venous thromboembolism (PA-VTE) but there is a suggestion that standard doses of low-molecular-weight heparin may not be effective. We conducted a large observational cohort study reviewing maternal outcomes in women who received extended thromboprophylaxis with enoxaparin for prevention of PA-VTE. We report a low rate of breakthrough VTE in women, the majority of whom received standard doses of enoxaparin. High rates of postpartum hemorrhage are reported in our cohort. Our data do not strongly support a move to increase doses of thromboprophylaxis for prevention of PA-VTE and raise the possibility that higher doses may increase bleeding complications and limit women's access to neuraxial analgesia/anesthesia.

BACKGROUND

Low-molecular-weight heparin is used to prevent pregnancy-associated venous thromboembolism (PA-VTE), but there are limited data to inform which women require thromboprophylaxis in pregnancy and debate about which low-molecular-weight heparin dose is effective and safe.

AIMS

To evaluate the efficacy and rate of complications using enoxaparin for thromboprophylaxis in a cohort of women at risk of PA-VTE managed between 1999 and 2014 at National Women's Hospital, a tertiary obstetric referral center in Auckland, New Zealand.

METHODS

A retrospective, observational study of women who received thromboprophylaxis with enoxaparin for prevention of PA-VTE while under the care of the obstetric or maternal fetal medicine team.

RESULTS

A total of 172 pregnancies in 123 women were identified. A single daily dose of 40 mg enoxaparin was used in 94.8% of pregnancies. Two breakthrough PA-VTEs occurred (1.2% [95% confidence interval, 0.32-4.14]). Postpartum hemorrhage ≥500 mL was reported in 36.6% of births and postpartum hemorrhage ≥1000 mL in 9.3% of births. Only four women were transfused. Neuraxial analgesia/anesthesia was used in 52.4% of births, including 39.6% of vaginal births.

CONCLUSION

Use of standard doses enoxaparin thromboprophylaxis in our cohort was effective at preventing PA-VTE. Neuraxial analgesia/anesthesia was used frequently during labor and birth;, using higher doses of enoxaparin may limit access to this. Postpartum hemorrhage was common and higher doses of thromboprophylaxis may increase obstetric bleeding complications. These data do not suggest an urgent need to consider higher doses of enoxaparin for thromboprophylaxis in this clinical setting.

Early Postpartum Venous Thromboembolism: Risk Factors and Predictive Index

The aim of our study was to quantify risk factors for venous thromboembolism (VTE) during the puerperal period. The case-control study was conducted in Women's Hospital, Zhejiang University, China, from January 2006 to December 2016; cases of hospitalized VTE within 1 week after delivery were identified according to International Classification of Diseases, Ninth Revision, Clinical Modification codes. Control postpartum women without VTE were randomly selected, matched on birth day, age, delivery mode, and number of fetus with 4:1 ratio. Clinical risk factors for postpartum VTE and coagulation parameters were analyzed. We found independent variables that were significantly related to postpartum VTE (all P < .05) in a binary logistic regression analysis included preeclampsia/eclampsia (odds ratio [OR], 2.89; 95% confidence interval [CI], 1.56-5.37) and postpartum hemorrhage (OR, 4.6; 95% CI, 1.71-12.40). D-dimer was the only biomarker that statistically significant associated with postpartum VTE in 3 days after delivery (all P < .05). These findings showed preeclampsia/eclampsia and postpartum hemorrhage were important risk factors for early VTE during puerperal period. A higher level of D-dimer was more meaningful than other coagulation parameters to suspect early thrombotic disease after delivery.

Venous thromboembolism prophylaxis may cause more harm than benefit: an evidence-based analysis of Canadian and international guidelines

A majority of deep vein thromboses identified in screening studies of hospitalized patients remain clinically insignificant. Guidelines based on these studies markedly overestimate the risk of clinical venous thromboembolism (VTE) and the benefit of heparin prophylaxis. Accordingly, in 2012, the American College of Chest Physicians (ACCP) removed screening studies from the 9th edition of its Antithrombotic and Thrombolytic Therapy guideline (AT9), and downgraded recommendations. Involvement of authors of the 8th edition (AT8) was restricted due to financial and intellectual conflicts of interest. However, the first author of AT8 subsequently wrote a "Getting Started Kit," widely distributed to help Canadian hospitals develop VTE protocols. Based on screening studies reporting asymptomatic VTE, it lacks estimates of the magnitudes of benefit or harm from low molecular weight heparin (LMWH), yet advises prophylaxis in almost all hospitalized patients. Most Canadian hospitals have implemented guidelines based on this kit. Guidelines from the U. K National Institute for Health and Care Excellence and the U.S. Agency for Healthcare Research and Quality recommend a similar approach. However, a critical review of evidence reveals that most hospitalized patients have a risk of clinical VTE equal to or lower than the bleeding risk from LMWH. Most hospitalized patients should not receive LMWH until and unless randomized trials show more benefit than harm. Guidelines recommending liberal LMWH prophylaxis in hospitalized patients are not evidence based and should be critically re-examined.

Prevention of venous thromboembolism in pregnant patients with a history of venous thromboembolic disease: A retrospective cohort study

BACKGROUND

Optimal prophylactic strategies in pregnant women with a history of venous thromboembolism (VTE) are unknown.

PATIENTS AND METHODS

We conducted a retrospective cohort study of consecutive pregnant patients with a previous VTE history. Patients were followed until 6 weeks postpartum. Patients with a previous unprovoked event (including antepartum VTE) received antenatal prophylaxis, mostly with low dose low molecular weight heparin (LMWH). All patients received prophylaxis for six weeks after delivery.

RESULTS

We included a total of 199 pregnancies in 142 women. Of these, 147 pregnancies occurred in women with unprovoked or estrogen-related VTE history and 52 pregnancies in women with provoked VTE. There were 8 recurrences in 199 pregnancies (4%; 95%CI: 2.05-7.73), of which 5 were antepartum recurrences (2.5%; 95%CI 1.08-5.75) and 3 were postpartum (1.5%; 95% CI 0.51-4.34). In the unprovoked VTE group there were 7 recurrences (4.7%; 95%CI: 2.32-9.50), whereas in the provoked VTE group there was 1 (1.9%; 95%CI: 0.34-10.12). There was one major bleeding event in a patient not receiving LMWH secondary to placental abruption.

CONCLUSION

This study suggests that the use of prophylactic doses of LMWH during pregnancy and puerperium, as described in this study, results in low occurrence of ante- and postpartum VTE recurrences in patients with previous VTE. Further studies are required to confirm this observation.

Risk Assessment and Management of Venous Thromboembolism in Women during Pregnancy and Puerperium (SAVE): An International, Cross-sectional Study

The clinical burden of obstetric venous thromboembolism (VTE) risk is inadequately established. This study assessed the prevalence and management of VTE risk during pregnancy and postpartum outside the Western world. This international, noninterventional study enrolled adult women with objectively confirmed pregnancy attending prenatal care/obstetric centers across 18 countries in Africa, Eurasia, Middle-East, and South Asia. Evaluations included proportions of at-risk women, prophylaxis as per international guidelines, prophylaxis type, factors determining prophylaxis, and physicians' awareness about VTE risk management guidelines and its impact on treatment decision. Data were analyzed globally and regionally. Physicians ( N  = 181) screened 4,978 women, and 4,010 were eligible. Of these, 51.4% were at risk (Eurasia, 90%; South Asia, 19.9%), mostly mild in intensity; >90% received prophylaxis as per the guidelines (except South Asia, 77%). Women in Eurasia and South Asia received both pharmacological and mechanical prophylaxes (>55%), while pharmacological prophylaxis (>50%) predominated in Africa and the Middle-East. Low-molecular-weight heparin was the pharmacological agent of choice. Prophylaxis decision was influenced by ethnicity, assisted reproductive techniques, caesarean section, and persistent moderate/high titer of anticardiolipin antibodies, though variable across regions. Prophylaxis decision in at-risk women was similar, irrespective of physicians' awareness of guidelines (except South Asia). A majority (>80%) of the physicians claimed to follow the guidelines. More than 50% of women during pregnancy and postpartum were at risk of VTE, and >90% received prophylaxis as per the guidelines. Physicians are generally aware of VTE risk and comply with guidelines while prescribing prophylaxis, although regional variations necessitate efforts to improve implementation of the guidelines.

Postpartum venous thromboembolism prophylaxis may cause more harm than benefit: a critical analysis of international guidelines through an evidence-based lens

Based on prediction models and expert opinion, most obstetric venous thromboembolism guidelines recommend low-molecular-weight heparin for many postpartum women, including most delivering by caesarean. Scrutiny reveals major oversights: prediction models are based on studies that report asymptomatic deep vein thrombosis; risk estimates are not adjusted for time exposure; and harm caused by heparin has been overlooked. The benefits of heparin are exaggerated and its harms are under-appreciated. Estimates of the numbers-needed-to-treat and harm are universally lacking. This paper critically reviews the evidence and quantifies the benefit and harm from low-molecular-weight heparin in postpartum women with common risk factors.

FUNDING

This work was unsponsored and unfunded.

TWEETABLE ABSTRACT

Randomised trials should demonstrate more benefit than harm before widespread postpartum low-molecular-weight heparin is recommended.

Preventing venous thromboembolism during pregnancy and postpartum: crossing the threshold

When should a patient with a known thrombophilia or prior venous thromboembolism (VTE) receive low-molecular-weight heparin (LMWH) prophylaxis during pregnancy and/or the postpartum period? Accurately predicting thrombotic and bleeding risks and knowing what to do with this information is at the heart of decision-making in these challenging scenarios. This article will explore the concept of a risk threshold from clinician and patient perspectives and provide guidance for the use of antepartum and postpartum LMWH prophylaxis in women with a known thrombophilia or prior VTE. Advice for the management of LMWH prophylaxis use around labor and delivery is also reviewed.

Guidance for the treatment and prevention of obstetric-associated venous thromboembolism

Venous thromboembolism (VTE), which may manifest as pulmonary embolism (PE) or deep vein thrombosis (DVT), is a serious and potentially fatal condition. Treatment and prevention of obstetric-related VTE is complicated by the need to consider fetal, as well as maternal, wellbeing when making management decisions. Although absolute VTE rates in this population are low, obstetric-associated VTE is an important cause of maternal morbidity and mortality. This manuscript, initiated by the Anticoagulation Forum, provides practical clinical guidance on the prevention and treatment of obstetric-associated VTE based on existing guidelines and consensus expert opinion based on available literature where guidelines are lacking.

Women's values and preferences for thromboprophylaxis during pregnancy: a comparison of direct-choice and decision analysis using patient specific utilities

BACKGROUND

Women with a history of venous thromboembolism (VTE) have an increased recurrence risk during pregnancy. Low molecular weight heparin (LMWH) reduces this risk, but is costly, burdensome, and may increase risk of bleeding. The decision to start thromboprophylaxis during pregnancy is sensitive to women's values and preferences. Our objective was to compare women's choices using a holistic approach in which they were presented all of the relevant information (direct-choice) versus a personalized decision analysis in which a mathematical model incorporated their preferences and VTE risk to make a treatment recommendation.

METHODS

Multicenter, international study. Structured interviews were on women with a history of VTE who were pregnant, planning, or considering pregnancy. Women indicated their willingness to receive thromboprophylaxis based on scenarios using personalized estimates of VTE recurrence and bleeding risks. We also obtained women's values for health outcomes using a visual analog scale. We performed individualized decision analyses for each participant and compared model recommendations to decisions made when presented with the direct-choice exercise.

RESULTS

Of the 123 women in the study, the decision model recommended LMWH for 51 women and recommended against LMWH for 72 women. 12% (6/51) of women for whom the decision model recommended thromboprophylaxis chose not to take LMWH; 72% (52/72) of women for whom the decision model recommended against thromboprophylaxis chose LMWH.

CONCLUSIONS

We observed a high degree of discordance between decisions in the direct-choice exercise and decision model recommendations. Although which approach best captures individuals' true values remains uncertain, personalized decision support tools presenting results based on personalized risks and values may improve decision making.