Hereditary risk factors for thrombophilia and probability of venous thromboembolism during pregnancy and the puerperium

Associations of blood pressure in the third trimester and risk of venous thromboembolism postpartum

Studies on the associations of blood pressure (BP) and the risk of venous thromboembolism (VTE) had been performed neither among pregnant women nor in Chinese population. This study included participants of pregnant women from a retrospective multicenter cohort, between May 2020 and April 2023. Systolic BP (SBP) and diastolic BP (DBP) of the participants were measured in the third trimester. The incidences of VTE (including deep venous thrombosis and/or pulmonary embolism) at 42 days postpartum were followed. With regards to SBP, pregnant women in the Q1 (≤114 mmHg), Q2 (115-122 mmHg), and Q4 group (≥131 mmHg) had increased risk of VTE than those in Q3 group (123-130 mmHg), with ORs 4.48 [1.69, 11.85], 3.52 [1.30, 9.59], and 3.17 [1.12, 8.99], respectively. Compared with pregnant women with the Q4 of DBP (≥85 mmHg), women of Q1 (≤71 mmHg) were found to have elevated risk of VTE (OR 2.73 [1.25, 5.96]). A one standard deviation decrease of DBP (9 mmHg) was related with 37% elevated risk of VTE (OR 1.37 [1.05, 1.79]). This study demonstrated a U-shaped association of SBP in the third trimester and VTE postpartum and inverse association of DBP in the third trimester and VTE postpartum.

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.

Diagnosis and treatment of venous thromboembolism during pregnancy relate to genetic polymorphism

OBJECTIVES

Previous research had shown that age, a positive family history, comorbidities, major surgical operations, gestation, and use of several medications could increase the incidence of venous thromboembolism (VTE). With the development of medical and clinical individualized treatment, many people exposed to above risk factors did not develop VTE, suggested that genetic factors are also involved in the development of VTE. In this review, we aim to summarize VTE diagnosis and treatment in pregnancy women related to gene polymorphism.

METHODS

A comprehensive electronic search using PubMed, MEDLINE, EMBASE and Web of Science was conducted to find relevant journal articles with key search terms including: "pregnancy OR pregnant," "venous thromboembolism OR VTE," "deep vein thrombosis OR DVT," "pulmonary embolism OR PE," and "genetic OR gene." Prominent publications from establishment of database till present were analysed to achieve a deeper understanding of VTE during pregnancy relate to genetic polymorphism, and the information was then collated to form this review.

RESULTS

The literature review revealed that inherited thrombophilia significantly associated with the development of VTE, especially the factor V Leiden (FVL) and prothrombin gene mutation (PGM). Furthermore, the role of methylenetetrahydrofolate reductase (MTHFR) gene mutation in the development of pregnancy-related VTE remains controversial, further study is required. In the present study, Marburg I polymorphism (G511 E), c.1538 G>A and c.1601 G>A in Factor V (FV), JAK2V617 F mutation were reported as an independent risk factor for VTE, there is no sufficient evidence to confirm the gene mutation is related to VTE during pregnancy, these factors appearing as another promising potential diagnostic marker of VTE during pregnancy. Besides, the dosages of heparin in the treatment of VTE during pregnancy need be adjusted according to gene polymorphism of these population, particularly FVL or PGM carriers, and this area is not studied deeply, it is worth further study.

CONCLUSION

Inherited thrombophilia significantly associated with the development of VTE, especially the FVL and PGM, however the relation between MTHFR gene mutation and pregnancy-related VTE remains controversial, further study is needed. In addition, the dosages of heparin in the treatment of VTE during pregnancy suggested to adjusted based on gene polymorphism in FVL and PGM, and establish better prediction models is a direction of future research.

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.

To Test or Not to Test: Routine Thrombophilia Diagnostic Screening of Women with Reproductive Failures

BACKGROUND

Recurrent reproductive failure is a global health issue affecting a significant number of women. Thrombophilias have been implicated as a possible cause. Inherited thrombophilias include a single nucleotide variant on factor V Leiden and prothrombin.

OBJECTIVE

The aim of this study was to evaluate the association between the following single nucleotide variants: factor V Leiden (c.1601G>A), the prothrombin gene (c.*97G>A) and the reproductive failure in the Polish population.

METHODS

The study was conducted in a group of 545 patients with recurrent pregnancy loss, RPL (≥2 miscarriages), and in a group of 641 patients with infertility. The distribution of genotypes for the selected variants were determined by RFLP-PCR and by the real-time PCR method.

RESULTS

A variant of the F5 gene was found in 5.14% of patients with RPL and in 6.08% of infertile women. A variant of the F2 gene was identified in 0.73% of patients with RPL and in 2.03% of women with infertility. The frequency in the study groups did not differ from that in the general population. No association between the studied variants of the F5 gene or the F2 gene and the predisposition to reproductive wastage was found.

CONCLUSIONS

Recommendations for routine thrombophilia testing in women with recurrent miscarriages should be revisited. The decision regarding testing should be made individually depending on additional factors indicating an increased risk of venous thromboembolism.

Assessment-based management of placenta-mediated pregnancy complications: Pragmatism until a precision medicine approach evolves

The management of pregnant women with thrombophilia and a history of gestational vascular complications remains debatable. Treatment of the latter is often based on clinical outcome rather than disease mechanism. While the use of venous thromboembolism prophylaxis in pregnancy is recommended for those at increased risk, the ability of anticoagulant and/or antiplatelet agents to lower the risk of placenta-mediated complications in this clinical setting remains controversial. The available guidelines are inconsistent in some situations, which reflects the limited evidence base. This review critically discusses risk assessment models (RAMs) and management strategies of women with thrombophilia and pregnancy complications, using clinical vignettes. RAMs, taking into account obstetric and thrombotic history as well as thrombophilia status, could drive a precision medicine approach, based on disease mechanism, and guide individual therapeutic interventions in high-risk clinical settings.

Genome-wide association analyses identified novel susceptibility loci for pulmonary embolism among Han Chinese population

BACKGROUND

A large proportion of pulmonary embolism (PE) heritability remains unexplained, particularly among the East Asian (EAS) population. Our study aims to expand the genetic architecture of PE and reveal more genetic determinants in Han Chinese.

METHODS

We conducted the first genome-wide association study (GWAS) of PE in Han Chinese, then performed the GWAS meta-analysis based on the discovery and replication stages. To validate the effect of the risk allele, qPCR and Western blotting experiments were used to investigate possible changes in gene expression. Mendelian randomization (MR) analysis was employed to implicate pathogenic mechanisms, and a polygenic risk score (PRS) for PE risk prediction was generated.

RESULTS

After meta-analysis of the discovery dataset (622 cases, 8853 controls) and replication dataset (646 cases, 8810 controls), GWAS identified 3 independent loci associated with PE, including the reported loci FGG rs2066865 (p-value = 3.81 × 10^-14), ABO rs582094 (p-value = 1.16 × 10^-10) and newly reported locus FABP2 rs1799883 (p-value = 7.59 × 10^-17). Previously reported 10 variants were successfully replicated in our cohort. Functional experiments confirmed that FABP2-A163G(rs1799883) promoted the transcription and protein expression of FABP2. Meanwhile, MR analysis revealed that high LDL-C and TC levels were associated with an increased risk of PE. Individuals with the top 10% of PRS had over a fivefold increased risk for PE compared to the general population.

CONCLUSIONS

We identified FABP2, related to the transport of long-chain fatty acids, contributing to the risk of PE and provided more evidence for the essential role of metabolic pathways in PE development.

Venous thromboembolism during pregnancy: Trends, incidence, and risk patterns in a large cohort population

OBJECTIVE

To determine the incidence and risk factors for pregnancy-associated venous thromboembolism (VTE).

METHODS

An observational retrospective study was conducted using data from 452 176 live births between the years 2010 and 2019. The study group consisted of women who were diagnosed with VTE during pregnancy or the postpartum period. The exclusion criteria included women who purchased anticoagulant drugs during pregnancy or postpartum. The hazard ratios (HRs) of VTE per week of each trimester and the postpartum period were calculated.

RESULTS

A total of 421 125 live births were included in the study. Among the study population, 302 cases (0.71 cases/1000 pregnancies) were diagnosed with VTE during pregnancy and postpartum. The overall rates of diagnosis did not change significantly during the study period but followed a declining trend in the postpartum period. The highest risk of VTE was found to be during the third trimester (HR 0.002% per week, 95% confidence interval [CI] 0.0016-0.0023), while the lowest rate was during the postpartum period (HR 0.0007% per week, 95% CI 0.0004-0.0011).

CONCLUSION

Pregnancy and the puerperium are well-established risk factors for VTE. The present study demonstrates a declining trend in the risk and incidence of VTE during the postpartum period, which can be explained by a liberal and effective VTE prevention policy.

A retrospective study on the use of low-molecular-weight heparin for prevention of pregnancy-related recurrent venous thromboembolism and obstetrical complications

BACKGROUND

The risk of venous thromboembolism (VTE) is increased during pregnancy and it is further increased together with pregnancy complications in women with personal history of VTE and thrombophilia abnormalities. It is unclear how the use of low-molecular-weight heparin (LMWH) may prevent such complications.

OBJECTIVE

To evaluate the potential benefits and risks of the use of LMWH for prevention of pregnancy-related VTE and obstetrical complications in the first pregnancy after a previous VTE.

METHODS

This retrospective cohort study includes fertile women referred to the Thrombosis Center from January 2000 to September 2018 for a thrombophilia work-up, after having had at least one previous VTE and one pregnancy thereafter. Data on pregnancy-related recurrent VTE, pregnancy outcomes and the use of LMWH were collected.

RESULTS

Among 208 women, no thrombosis or major bleeding was recorded in 138 pregnancies conducted with LMWH, whereas 10 VTE (14%) were recorded in 70 pregnancies conducted without. Nine women (90%) with recurrent VTE had had a previous hormone-related event. The incidence of miscarriage was lower in pregnancies with LMWH than in those without (11% vs. 26%, relative risk 0.4, 95% confidence interval: 0.2-0.8), whereas late obstetrical complications and terminations were similar in the two groups. The prevalence of terminations was doubled in women with thrombophilia (12%) than in those without (6%).

CONCLUSIONS

LMWH prophylaxis during pregnancy appears to be effective and safe for the prevention of recurrent VTE and may reduce the incidence of miscarriage.

Evaluation of Low-Molecular-Weight Heparin Treatment on First- and Second-Trimester Screening Test Results

Background The serum markers used in first- and second-trimester screening tests can be affected by different causes such as smoking, infertility treatment, and the presence of diabetes mellitus, which should be considered by obstetricians when giving information to patients. Low molecular weight heparin (LMWH) has a critical importance in the prophylaxis of deep vein thrombosis both in the antenatal and postnatal period. The aim of the current study is to investigate the effect of LMWH use on the first- and second-trimester screening results. Methods A retrospective analysis in our outpatient clinic between July 2018 and January 2021 of first- and second-trimester screening test results was conducted to assess the impact of LMWH treatment for patients with thrombophilia who started LMWH after pregnancy was detected were included. Test results were obtained as a multiple of median (MoM) combined with ultrasound measurements, maternal serum markers, and maternal age in addition to the nuchal translucency first-trimester test. Results The pregnancy-associated plasma protein-A (PAPP-A) MoM was lower and alpha-fetoprotein (AFP) and unconjugated estriol (uE3) MoMs were higher in patients treated with LMWH than in the control group (0.78 MoM vs 0.96 MoM; 1.00 MoM vs 0.97 MoM; and 0.89 MoM vs 0.76 MoM, respectively). Human chorionic gonadotropin (HCG) levels did not differ between groups at either time point. Conclusions Treatment of pregnant women with LMWH for thrombophilia may change the MoM values of serum markers for both first- and second-trimester screening tests. Obstetricians should be aware of this when advising screening tests to thrombophilia patients and should consider offering fetal DNA tests for this group instead.

The Proper Diagnosis of Thrombophilic Status in Preventing Fetal Growth Restriction

Fetal growth restriction is an important part of monitoring a pregnancy. Because guidelines or diagnostic criteria for either minor or major thrombophilia are scarce, this systematic review aims to summarize the present knowledge in the field. We performed the CRD42022376006 protocol in Prospero with a systematic literature search in PubMed and Web of Science databases and included original full-text articles (randomized control trials and clinical trials) from the last 10 years, published in English, and with the "thrombophilia AND (pregnancy OR diagnostic criteria) AND fetal growth restriction" criteria. After two researchers extracted the articles of interest, they were assessed using the Newcastle-Ottawa Scale and eight articles were included. The elements from the thrombophilia diagnostic predict IUGR, factor V Leiden mutation, MTHFR C667T mutation, protein S deficiency, antithrombin deficiency, factor VII polymorphism, and antiphospholipid antibodies, while the association of protein C, PAI-1 and certain combinations of mutations are still under debate and require the collection of more data. The present systematic review provides an extensive picture of the actual knowledge about thrombophilia diagnosis and its links with pregnancy complications, such as intrauterine growth restriction, despite its limitation in the inclusion of other actually debated disorders such as PAI-1 mutation, protein C deficiency and other thrombophilia types.

A Retrospective Assessment of Thrombophilia in Pregnant Women with First and Second Trimester Pregnancy Loss

Recurrent Pregnancy Loss (RPL) affects between 1% to 5% of women of reproductive age. It is widely believed that RPL is a complex disorder that is influenced by chromosomal abnormalities, genetic mutations, uterine anatomic deformity, endocrine dysfunction, immunologic factors, infections, and the environment. Thrombotic disorders are a frequent cause of RPL, accounting for almost half of all cases; however, in the rest of the cases, the cause of RPL remains unclear. Therefore, in this study, it was planned to determine the genetic mutations involved in RPL during the first and second trimester of pregnancy. An observational retrospective cohort study was conducted in 2021, collecting data from 157 first trimester miscarriages and 54 s trimester pregnancies. All patients with a panel of laboratory and genetic analysis for thrombophilia were included for data analysis. It was observed that four factors were significantly more prevalent in one of the groups. Factor V Leiden (FVL) homozygosity and antiphospholipid syndrome (APS) antibodies were statistically significantly more common in pregnant women who suffered first trimester pregnancy losses. On the other hand, Protein C deficiency and Glycoprotein Ia polymorphism were statistically significantly more frequent in the second trimester group. The strongest independent risk factors for first trimester pregnancy loss were FVL and prothrombin (PT) compound mutations (OR = 3.11), followed by FVL homozygous mutation (OR = 3.66), and APS antibodies (OR = 4.47). Regarding second trimester pregnancy loss risk factors, the strongest were FVL and PT compound (OR = 3.24), followed by Glycoprotein Ia polymorphism (OR = 3.61), and respectively, APS antibodies (OR = 3.85). Numerous thrombophilic risk factors for early and late pregnancy loss have been found, including several mutations that seem to occur more often either during the first or the second trimester. Even though we are aware of risk-free and efficient diagnostics for thrombophilia abnormalities, no intervention has been proved to be clearly successful after the detection of these variables.

Management of Antithrombin Deficiency in Pregnancy

Antithrombin (AT) deficiency is a high-risk thrombophilia and a rare condition. The risk of venous thromboembolism (VTE) is increased in AT-deficient women during pregnancy and the postpartum period and is especially high in women with a prior history of VTE. A thorough assessment of VTE risk is recommended in pregnant AT-deficient women, comprising the degree and type of AT deficiency, genetic mutations, personal and family history, and additional preexisting or pregnancy-specific risk factors. Due to a lack of adequate study data, there is limited guidance on the management of AT deficiency in pregnancy, including the need for prophylactic anticoagulation, the appropriate dose of low-molecular-weight heparin (LMWH), and the role of AT substitution. LMWH is the medication of choice for the pharmacological prophylaxis and treatment of VTE in pregnancy. Patients with a history of VTE should receive full-dose LMWH during pregnancy and the postpartum period. AT concentrates are a treatment option when anticoagulation is withheld in potentially high-risk events such as childbirth, bleeding, or surgery and in cases of acute VTE despite the use of therapeutic dose anticoagulation. Women with AT deficiency should be counseled at specialized centers for coagulation disorders or vascular medicine, and close cooperation between obstetricians and anesthesiologists is warranted before delivery and during the peripartum period.

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.

Risk factors, diagnosis and management of venous thromboembolic disease in pregnancy

Venous thromboembolism (VTE) in pregnancy is a leading cause of maternal morbidity and mortality. However, despite the significant associated clinical burden and potentially devastating societal impact, there is still a paucity of data surrounding its prevention and management. Consequently, international guideline recommendations vary widely. Exclusion of pregnant women from clinical trials in the past has contributed to knowledge gaps. However, recently published and ongoing studies demonstrate that excellent clinical trials in pregnancy are achievable. This review will discuss prevention, diagnosis and treatment of VTE in pregnancy, and will also explore priorities for future research.

Venous thromboembolism in pregnancy is a leading cause of maternal morbidity and mortality. However, individualised clinical risk assessment and recent advances in clinical prediction rules for pulmonary embolism have the potential to improve management.https://bit.ly/3mjtHg2

Prevention of venous thromboembolism in pregnant women with congenital antithrombin deficiency: a retrospective study of a candidate protocol

BACKGROUND

The best thromboprophylaxis for pregnant women with congenital antithrombin deficiency (CAD) is controversial.

OBJECTIVE

To clarify the effectiveness of a protocol for venous thromboembolism (VTE) prevention in pregnant women with CAD.

METHODS

Women at high risk of VTE were administered antithrombin concentrate and heparin after conception, whereas those at low risk of VTE were administered heparin alone until delivery. All women received antithrombin concentrate at delivery except for one who was diagnosed with CAD.

RESULTS

Ten women had CAD, including one in the high-risk group and nine in the low-risk group. No women had VTE at delivery as per the protocol for VTE prevention. Almost all women had increased antithrombin activity before delivery followed by maintenance at ≥ 70% due to antithrombin concentrate administration. VTE prophylaxis during and after delivery was successful in all women with CAD. However, one woman in the low-risk group did not receive heparin and developed VTE induced by severe hyperemesis at 9 gestational weeks, before the diagnosis of CAD. Women in the high-risk group received antithrombin concentrate after delivery but had increased D-dimer levels at postpartum.

CONCLUSIONS

Our protocol to prevent VTE in pregnant women with CAD is safe and effective.

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.

Association Between Maternal Weight Gain in Different Periods of Pregnancy and the Risk of Venous Thromboembolism: A Retrospective Case-Control Study

BACKGROUND

Venous thromboembolism (VTE) remains an important cause of maternal deaths. Little is known about the associations of specific periods of gestational weight gain (GWG) with the category of VTE, pulmonary embolism (PE), or deep venous thrombosis (DVT) with or without PE.

METHODS

In a retrospective case-control study conducted in Shanghai First Maternity and Infant Hospital from January 1, 2017 to September 30, 2021, cases of VTE within pregnancy or the first 6 postnatal weeks were identified. Controls without VTE were randomly selected from women giving birth on the same day as the cases, with 10 controls matched to each case. Total GWG and rates of early, mid, and late GWG values were standardized into z-scores, stratified by pre-pregnant body mass index (BMI). The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated through multivariate logistic regression models.

RESULTS

There were 196 cases (14.4 per 10,000) of VTE within pregnancy or the first 6 postnatal weeks were identified. Higher total weight gain was associated with increased risks of PE (aOR, 13.22; 95% CI, 2.03-85.99) and VTE (OR, 10.49; 95% CI, 1.82-60.45) among women with underweight. In addition, higher total weight gain was associated with increased risk of PE (aOR, 2.06; 95% CI, 1.14-3.72) among women with healthy weight. Similarly, rate of higher early weight gain was associated with significantly increased risk for PE (aOR, 2.15; 95% CI, 1.05-4.42) among women with healthy BMI. The lower rate of late weight gain was associated with increased risks of PE (aOR, 7.30; 95% CI, 1.14-46.55) and VTE (OR, 7.54; 95% CI, 1.20-47.57) among women with underweight. No significant associations between maternal rate of mid GWG and increased risk for any category of VTE, PE, or DVT with or without PE were present, regardless of maternal pre-pregnant BMI.

CONCLUSION

The GWG associations with the category of VTE, PE, or DVT with or without PE differ at different periods of pregnancy. In order to effectively improve maternal and child outcomes, intensive weight management that continues through pregnancy may be indispensable.

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.

Approach to the Evaluation and Treatment of Venous Thromboembolism in Pregnancy

Thrombosis in pregnancy is a major cause of maternal and fetal morbidity and mortality. Risk stratification of venous thromboembolism (VTE) during pregnancy is complex. The hypercoagulability observed in pregnant women can reduce bleeding during childbirth, but may cause thrombosis especially in the presence of additional prothrombotic risk factors such as antiphospholipid antibodies or genetic thrombophilic defects. The availability of large datasets allows for the identification of additional independent risk factors, including assisted reproductive technologies (ARTs), endometriosis, and recurrent pregnancy loss. Data on the risk of VTE linked to COVID-19 in pregnant women are very limited, but suggest that infected pregnant women have an increased risk of VTE. Current guidelines on the prevention and treatment of VTE in pregnancy are based on available, albeit limited, data and mainly present expert opinion. Low-molecular-weight heparins (LMWHs) are the mainstay of anticoagulation to be employed during pregnancy. Administration of LMWH for VTE treatment in pregnancy should be based on the personalized approach, taking into account a weight-based adjusted scheme. During gestation, due to physiological changes, in women at high risk of VTE, monitoring of anti-Xa activity is performed to ensure adequate LMWH dosing. As for the treatment duration for pregnant women with acute VTE, guidelines suggest that anticoagulation should be continued for at least 6 weeks postpartum for a minimum total duration of therapy of 3 months.

Clinical guidance for peripartum management of patients with hereditary thrombophilia

Hereditary thrombophilia is a condition in which individuals are susceptible to the formation of thrombi due to a hereditary deficiency in anticoagulant factors, antithrombin (AT), protein C (PC), or protein S (PS). Many Japanese thrombophilia patients have PS deficiency, especially PS p.K196E (also called as PS Tokushima), which is exclusive to the Japanese population, and thrombosis sometimes occurs during pregnancy. At present, no management guidelines for pregnancy and delivery in thrombophilia patients have been developed. The Study Group for Hereditary Thrombophilia, one of the research groups of blood coagulation abnormalities in the Research Program on Rare and Intractable Diseases supported with the Research Grants of the Ministry of Health, Labour and Welfare Science, has therefore developed this clinical guidance to provide healthcare workers with necessary information on safe pregnancy, parturition and neonatal management, adopting a format of responses to seven clinical questions (CQ). At the end of each answer, the corresponding Recommendation Level (A, B, C) is indicated.

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.

Prevention of Venous Thromboembolism in 2020 and Beyond

Venous thromboembolism (VTE) is the third most common cause of vascular mortality worldwide and comprises deep-vein thrombosis (DVT) and pulmonary embolism (PE). In this review, we discuss how an understanding of VTE epidemiology and the results of thromboprophylaxis trials have shaped the current approach to VTE prevention. We will discuss modern thromboprophylaxis as it pertains to genetic risk factors, exogenous hormonal therapies, pregnancy, surgery, medical hospitalization, cancer, and what is known thus far about VTE in COVID-19 infection.

Prevention of Venous Thromboembolism during Pregnancy and the Puerperium with a Special Focus on Women with Hereditary Thrombophilia or Prior VTE-Position Paper of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH)

Venous thromboembolism (VTE) is a major cause of maternal morbidity during pregnancy and the postpartum period. Because there is a lack of adequate study data, management strategies for the prevention of VTE during pregnancy have mainly been deduced from case-control and observational studies and extrapolated from recommendations for non-pregnant patients. The decision for or against pharmacologic thromboprophylaxis must be made on an individual basis weighing the risk of VTE against the risk of adverse side effects such as severe bleeding complications. A comprehensive, multidisciplinary approach is often essential as the clinical scenario is made more complex by the specific obstetric context, especially in the peripartum period. As members of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH), we summarize the evidence from the available literature and aim to establish a more uniform strategy for VTE risk assessment and thromboprophylaxis in pregnancy and the puerperium. In this document, we focus on women with hereditary thrombophilia, prior VTE and the use of anticoagulants that can safely be applied during pregnancy and the lactation period.

Managing thromboembolic risk in patients with hereditary and acquired thrombophilias

While we are now able to diagnose inherited thrombophilias in a substantial number of patients with venous thromboembolism (VTE), the initial hope that their presence would inform recurrence risk and thus decisions on anticoagulation duration has largely been disappointing. Indeed, the presence or absence of transient provoking risk factors has proven to be the most important determinant of VTE recurrence risk. Thus, particular attention to transient acquired risk factors for VTE remains paramount, as they have generally been shown to carry more prognostic weight than inherited thrombophilias. The presence of other acquired risk factors may require additional management considerations, whether pertaining to anticoagulant choice, as in antiphospholipid antibody syndrome, or to addressing a new predisposing medical condition, as in malignancy. Antithrombin deficiency or the presence of ≥1 thrombophilic defect may be exceptions that can have a role in prognostication; however, as illustrated in this review through several case vignettes, interpretation and clinical application of the results of inherited thrombophilia testing is nuanced. We have chosen to focus on cases in which patients have been identified as having thrombophilic defects rather than the indications for undertaking testing in the first place or the extent of investigation. Management decisions in such cases ultimately hinge on individualized consideration of the benefits and risks of anticoagulation along with patient preference rather than on an algorithmic pathway based on thrombophilia status.

Risk of pregnancy-related venous thromboembolism and obstetrical complications in women with inherited type I antithrombin deficiency: a retrospective, single-centre, cohort study

BACKGROUND

Inherited quantitative (type I) deficiency of plasma antithrombin is associated with a high risk of venous thromboembolism, which further increases in pregnancy. Inherited thrombophilia also increases the risk of obstetrical complications, but data on maternal and fetal outcomes in women with antithrombin deficiency are scarce. The aim of this study was to evaluate the risk of pregnancy-associated venous thromboembolism and obstetrical complications in women with type I antithrombin deficiency.

METHODS

In this single-centre, retrospective cohort study, women who had been referred to our Hemophilia and Thrombosis Centre, Milan, Italy for a thrombophilia work-up from Jan 1, 1980, to Jan 1, 2018, with type I antithrombin deficiency and who had had at least one pregnancy were included. Women with type II anthithrombin deficiency were excluded from the study. Data on pregnancy-associated venous thromboembolism, pregnancy outcomes, and the use of low-molecular-weight heparin (LMWH) were collected to evaluate the risk of pregnancy-associated venous thromboembolism and obstetrical complications with or without use of LMWH.

FINDINGS

126 women had been referred to the hospital, of whom 88 (70%) had had at least one pregnancy. Eight were excluded because of referral for venous thromboembolism during pregnancy or the puerperium, resulting in 80 (63%)women evaluated for the risk of venous thromboembolism. One woman was excluded because of referral for obstetrical complications, resulting in 87 (69%) evaluated for risk of obstetrical complications. We observed three events of venous thromboembolism in 43 pregnancies in women treated with LMWH (7·0%, 95% CI 1·8-17·8), and 17 events in 146 pregnancies in women who did not receive LMWH (11·6%, 7·2-17·6; relative risk [RR] 0·6, 95% CI 0·2-1·9; p=0·57). The risk of venous thromboembolism without LMWH was 5·4% (95% CI 0·9-16·7) in women with a negative family history of venous thromboembolism, and 11·8% (6·4-19·6) in those with a positive family history of venous thromboembolism. Of the 87 women evaluated for the risk of obstetrical complications, miscarriages occurred in 6 (13%) of 45 pregnant women treated with LMWH and 32 (20%) of 161 women who did not receive LMWH (terminations excluded). Late obstetrical complications occurred in 11 (24%) of women treated with LMWH and nine (6%) in those who did not receive LMWH (RR 4·4, 95% CI 1·9-9·9; p=0·0006).

INTERPRETATION

Our results confirm that women with type I antithrombin deficiency have a high risk of first or recurrent venous thromboembolism during pregnancy. The risk of venous thromboembolism is highest in women with a positive family history of the condition, but still relevant in those with a negative family history, suggesting that LMWH prophylaxis should also be considered in these patients.

FUNDING

None.

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.

Evaluation of unmet clinical needs in prophylaxis and treatment of venous thromboembolism in at-risk patient groups: pregnancy, elderly and obese patients

BACKGROUND

Venous thromboembolism (VTE) accounts for an estimated 900,000 cases per year in the US alone and constitutes a considerable burden on healthcare systems across the globe.

OBJECTIVE

To understand why the burden is so high, qualitative and quantitative research was carried out to gain insights from experts, guidelines and published studies on the unmet clinical needs and therapeutic strategies in VTE prevention and treatment in three populations identified as being at increased risk of VTE and in whom VTE prevention and treatment were regarded as suboptimal: pregnant women, the elderly and obese patients.

METHODOLOGY

A gap analysis methodology was created to highlight unmet needs in VTE management and to discover the patient populations considered most at risk. A questionnaire was devised to guide qualitative interviews with 44 thrombosis and haemostasis experts, and a review of the literature on VTE in the specific patient groups from 2015 to 2017 was completed. This was followed by a Think Tank meeting where the results from the research were discussed.

RESULTS

This review highlights the insights gained and examines in detail the unmet needs with regard to VTE risk-assessment tools, biomarkers, patient stratification methods, and anticoagulant and dosing regimens in pregnant women, the elderly and obese patients.

CONCLUSIONS

Specifically, in pregnant women at high risk of VTE, low-molecular-weight heparin (LMWH) is the therapy of choice, but it remains unclear how to use anticoagulants when VTE risk is intermediate. In elderly patients, evaluation of the benefit of VTE prophylaxis against the bleeding risk is particularly important, and a head-to-head comparison of efficacy and safety of LMWH versus direct oral anticoagulants is needed. Finally, in obese patients, lack of guidance on anticoagulant dose adjustment to body weight has emerged as a major obstacle in effective prophylaxis and treatment of VTE.

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.

Unusual thrombosis or pregnancy complications associated to ovarian cancers: two clinical cases

AIM

Using illustrative cases of two patients with ovarian cancer who developed unusual thrombosis in pregnancy, to describe the difficulties in diagnosing and managing such patients.

METHODS

We present the analysis of two cases of thrombosis of unusual localization (central artery of the retina and transverse and sigmoid sinus thrombosis) during pregnancy in women with hidden ovarian cancer.

RESULTS

In both cases, the symptomatic of unususal thrombosis was interpreted as a manifestation of eclampsia, leading to a choice of non-optimal obstetric tactics on a background of hidden ovarian cancer, which in both cases were diagnosed only postpartum.

CONCLUSIONS

Pregnancy itself is a risk factor for thrombotic complications and in case malignancy develops in parallel with pregnancy, this risk is multiplied. In patients with ovarian cancer, difficulties arise both in detecting the tumor itself due to the enlarged uterus and in interpreting some of the symptoms, which can be regarded as a manifestation of pregnancy complications.

Pregnancy and Pulmonary Embolism

Venous thromboembolism (VTE), referring to both deep vein thrombosis and pulmonary embolism, is a leading cause of death in the developed world during pregnancy. This increased risk is attributed to the Virchow triad, inherited thrombophilias, along with other standard risk factors, and continues for up to 6 to 12 weeks postpartum. During the peripartum period, women should be risk stratified and preventive measures should be initiated based on their risk. Diagnostic tests and treatment strategies commonly used in VTE differ in pregnancy. An understanding of these differences is imperative to diagnose with confidence and to treat appropriately.

Safety and efficacy of adjusted-dose enoxaparin in pregnant patients with increased risk for venous thromboembolic disease

OBJECTIVE

To assess the efficacy and safety of anti-Xa guided dose-adjusted low molecular weight heparin (LMWH) thromboprophylaxis in at-risk pregnant women.

METHODS

This single-center retrospective study was conducted at a quaternary hospital in Johannesburg, South Africa. We analyzed clinical and laboratory data for pregnant patients referred between January 1, 1999, and May 1, 2017, with an increased risk of venous thromboembolic disease (VTED) and treated with prophylactic LMWH adjusted according to anti-Xa levels. The efficacy endpoint was pregnancy-related VTED and/or pregnancy loss despite anti-Xa guided dose-adjusted LMWH thromboprophylaxis.

RESULTS

We reviewed data for 113 consecutive pregnant patients with 151 pregnancies referred for prophylactic LMWH. Prevalence of pregnancy-related VTED was 1.3% (95% confidence interval [CI] 0.1-4.7), which is lower than that reported in the literature for fixed-dose thromboprophylaxis in similar at-risk groups. One venous thromboembolism event occurred in the antenatal period (despite adequate prophylaxis) and the second in the postpartum period (related to prolonged labor). Prevalence of pregnancy-related bleeding was 2% (95% CI 0.4-5.7) with all bleeding events considered to be minor and unrelated to LMWH therapy.

CONCLUSION

This study demonstrated the efficacy and safety of anti-Xa dose-adjusted LMWH thromboprophylaxis in at-risk pregnant patients.

Hypercoagulable states in arterial and venous thrombosis: When, how, and who to test?

Evaluation for underlying hypercoagulable states in patients with thrombosis is a frequent clinical conundrum. Testing for thrombophilias is often reflexively performed without strategic approach nor clear appreciation of the clinical implications of such results. Guidelines vary in the appropriate utilization of thrombophilia testing. In this review, we discuss the more commonly encountered inherited and acquired thrombophilias, their association with initial and recurrent venous thromboembolism, arterial thromboembolism, and role in women's health. We suggest an approach to thrombophilia testing guided by the clinical presentation, suspected pathophysiology, and an understanding of how such results may affect patient care.

Pregnancy and Pulmonary Embolism

Venous thromboembolism (VTE), referring to both deep vein thrombosis and pulmonary embolism, is a leading cause of death in the developed world during pregnancy. This increased risk is attributed to the Virchow triad, inherited thrombophilias, along with other standard risk factors, and continues for up to 6 to 12 weeks postpartum. During the peripartum period, women should be risk stratified and preventive measures should be initiated based on their risk. Diagnostic tests and treatment strategies commonly used in VTE differ in pregnancy. An understanding of these differences is imperative to diagnose with confidence and to treat appropriately.

Therapeutic Options in Pregnant Women with Thrombophilia Depending on the Genetic Mutations- a Prospective Study

The aim is to evaluate the effects of anticoagulant therapy (Enoxaparine) compared to antiaggregant therapy (Aspirin) on pregnancy outcome depending on the mutational status of clotting factors. The study was conducted prospectively over a 2 years period and included 110 pregnant women, of whom 80 patients diagnosed with hereditary thrombophilia and 30 healthy pregnant women, representing the control group. After careful observation, we concluded a positive influence of Enoxaparine on pregnancy outcome in pregnant women homozygous carriers for factor V Leiden gene mutation and compound heterozygous for Factor V Leiden and Prothrombin G20210A gene mutation. The study did not find significant positive results in women with heterozygous Factor V Leiden and G20210A prothrombin gene mutation who received anticoagulant therapy as well as pregnant women who received low-dose Aspirin compared with controls.

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.

Pregnancy, thrombophilia, and the risk of a first venous thrombosis: systematic review and bayesian meta-analysis

Objective To provide evidence to support updated guidelines for the management of pregnant women with hereditary thrombophilia in order to reduce the risk of a first venous thromboembolism (VTE) in pregnancy.Design Systematic review and bayesian meta-analysis.Data sources Embase, Medline, Web of Science, Cochrane Library, and Google Scholar from inception through 14 November 2016.Review methods Observational studies that reported on pregnancies without the use of anticoagulants and the outcome of first VTE for women with thrombophilia were eligible for inclusion. VTE was considered established if it was confirmed by objective means, or when the patient had received a full course of a full dose anticoagulant treatment without objective testing. Results 36 studies were included in the meta-analysis. All thrombophilias increased the risk for pregnancy associated VTE (probabilities ≥91%). Regarding absolute risks of pregnancy associated VTE, high risk thrombophilias were antithrombin deficiency (antepartum: 7.3%, 95% credible interval 1.8% to 15.6%; post partum: 11.1%, 3.7% to 21.0%), protein C deficiency (antepartum: 3.2%, 0.6% to 8.2%; post partum: 5.4%, 0.9% to 13.8%), protein S deficiency (antepartum: 0.9%, 0.0% to 3.7%; post partum: 4.2%; 0.7% to 9.4%), and homozygous factor V Leiden (antepartum: 2.8%, 0.0% to 8.6%; post partum: 2.8%, 0.0% to 8.8%). Absolute combined antepartum and postpartum risks for women with heterozygous factor V Leiden, heterozygous prothrombin G20210A mutations, or compound heterozygous factor V Leiden and prothrombin G20210A mutations were all below 3%. Conclusions Women with antithrombin, protein C, or protein S deficiency or with homozygous factor V Leiden should be considered for antepartum or postpartum thrombosis prophylaxis, or both. Women with heterozygous factor V Leiden, heterozygous prothrombin G20210A mutation, or compound heterozygous factor V Leiden and prothrombin G20210A mutation should generally not be prescribed thrombosis prophylaxis on the basis of thrombophilia and family history alone. These data should be considered in future guidelines on pregnancy associated VTE risk.

Factors Associated with Contralateral Deep Venous Thrombosis after Iliocaval Venous Stenting

BACKGROUND

The majority of iliac venous obstructions occur on the left side, and endovascular therapy has become the first line treatment for this condition. A left common iliac venous stent will protrude into the inferior vena cava (IVC) to some extent, thereby covering the contralateral common iliac vein (CIV) outflow. This may increase the risk of thrombosis of the contralateral iliac vein. The aim of this paper was to determine the rate of, and factors associated with, contralateral lower limb venous thrombosis after stenting, and to evaluate the results of salvage revascularisation.

METHODS

A total of 376 patients (102 from UCH, Galway, Ireland, 2008-16, and 274 from, CHU Nord, Marseille, France, 2000-15) with symptomatic acute or chronic left iliocaval venous obstruction were retrospectively evaluated. Either duplex ultrasound scanning (DUS) or computed tomographic venography (CTV) was used for pre- and post-operative imaging. Data were collected from the PACS system (IMPAX, Agfa, BE) of the Radiology Department, UCH, Galway, and from the electronic medical records of Vascular Surgery department, CHU Nord, Marseille.

RESULTS

The median age of stented patients was 46 (range 15-86 years), 80% were female (301/376). Following left CIV stent placement, 10 patients later presented with a right (contralateral) iliac deep venous thrombosis (DVT) resulting in a cumulative incidence of contralateral DVT of 4% according to Kaplan-Meier analysis. Acute DVT (p=.001), non-compliance with the prescribed 6 months anticoagulation (p = 0.05), pre-operative contralateral internal iliac vein (IIV) thrombosis (p = 0.001), and pre-existing IVC filter placement (p = 0.003) were all statistically significantly associated with contralateral DVT. All patients with symptomatic contralateral iliac DVT underwent clot removal in the acute phase. The primary patency of these limbs was 100% at 3 years.

CONCLUSION

Stent placement across the iliocaval confluence from the left CIV is associated with a low but definite rate of contralateral iliac vein thrombosis. Acute DVT, pre-operative contralateral IIV thrombosis, pre-existing IVC filters, and anticoagulation non-compliance are significant risk factors.

A case that illustrates the challenges of managing pregnant patients with antithrombin deficiency: More questions than answers

Using an illustrative case of a patient with antithrombin (AT) deficiency who developed a recurrent venous thromboembolism (VTE) in pregnancy despite therapeutic low-molecular-weight heparin (LMWH), we highlight what is known in the literature and address areas of controversy through a series of questions around the case. The questions we address include the role of anti-Xa monitoring for patients with past VTE on antepartum LMWH, what treatment regimen is recommended for pregnant patients who develop a recurrent VTE while on therapeutic anticoagulation, the role of antepartum AT concentrate prophylaxis, and the management of labor/delivery, epidural anesthesia and postpartum anticoagulation. We also describe practical considerations for use of AT concentrate, including teaching our patient to self-infuse AT concentrate at home with support of a hemophilia treatment center (HTC), and the direct and indirect costs of AT concentrate for secondary prophylaxis.

'To test or not to test', the arguments for and against thrombophilia testing in obstetrics

Clinicians increasingly investigate women for thrombophilias due to their associations with venous thromboembolism and placenta-mediated pregnancy complication. These associations, however, are modest and based largely on retrospective data from studies with heterogeneous classifications and populations, leading to discordance between evidence and guidelines. Current evidence suggests a contributory rather than causative role for thrombophilia in placenta-mediated pregnancy complication and venous thromboembolism. With little evidence of benefit from antithrombotic therapy in placenta-mediated pregnancy complication, thrombophilia screening remains controversial. Given the low absolute risk of placenta-mediated pregnancy complication and gestational venous thromboembolism with heritable thrombophilia, universal screening is inappropriate. Selective screening for antiphospholipid syndrome is supported by robust evidence of benefit. Conversely, selective screening for heritable thrombophilia has not been shown to effectively manage placenta-mediated pregnancy complication. Therefore, at present heritable thrombophilia screening is not warranted for placenta-mediated pregnancy complication. Until we have better evidence from better stratified patient groups, caution should remain if we wish to practice evidence-based medicine.