Search

Hereditary and acquired thrombophilia are risk factors for venous thromboembolism (VTE). Whether testing helps guide management decisions is controversial. These evidence-based guidelines from the American Society of Hematology (ASH) intend to support decision making about thrombophilia testing. ASH formed a multidisciplinary guideline panel covering clinical and methodological expertise and minimizing bias from conflicts of interest. The McMaster University GRADE Centre provided logistical support, performed systematic reviews, and created evidence profiles and evidence-to-decision tables. The Grading of Recommendations Assessment, Development, and Evaluation approach (GRADE) was used. Recommendations were subject to public comment. The panel agreed on 23 recommendations regarding thrombophilia testing and associated management. Nearly all recommendations are based on very low certainty in the evidence due to modeling assumptions. The panel issued a strong recommendation against testing the general population before starting combined oral contraceptives (COCs) and conditional recommendations for thrombophilia testing in the following scenarios: (a) patients with VTE associated with nonsurgical major transient or hormonal risk factors; (b) patients with cerebral or splanchnic venous thrombosis, in settings where anticoagulation would otherwise be discontinued; (c) individuals with a family history of antithrombin, protein C, or protein S deficiency when considering thromboprophylaxis for minor provoking risk factors and for guidance to avoid COCs/hormone replacement therapy; (d) pregnant women with a family history of high-risk thrombophilia types; and (e) patients with cancer at low or intermediate risk of thrombosis and with a family history of VTE. For all other questions, the panel provided conditional recommendations against testing for thrombophilia., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

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., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Inherited thrombophilia is a blood coagulation disorder that increases the risk for venous thromboembolism (VTE). During the last decades, the practice of testing has evolved from testing selected populations, leading to high perceived risks, to broad testing for various conditions that included VTE, arterial thrombosis, and pregnancy complications. Because results of such tests usually do not guide treatment decisions, not testing patients with VTE for inherited thrombophilia is on the "Choosing Wisely" list endorsed by multiple specialty societies, including ASH. Inherited thrombophilia can be regarded a double-edged sword, as despite the rationale not to test, it is still being performed frequently. Another way of seeing inherited thrombophilia as a double-edged sword lies in its 2-sided association with reproduction, both in men and in women. Current areas of research are whether women with inherited thrombophilia and pregnancy complications benefit from anticoagulant therapy with regard to improving the chance of a successful pregnancy. Potential effects of inherited thrombophilia, most notably factor V Leiden, on improved embryo implantation in women and sperm counts in men are intriguing, but are currently poorly understood., (© 2016 by The American Society of Hematology. All rights reserved.)

The risk of thrombosis in individuals with rare compound thrombophilias, homozygous factor V Leiden (FVL) plus heterozygous prothrombin G20210A (PTM), homozygous PTM plus heterozygous FVL, and homozygous FVL plus homozygous PTM, is unknown. We identified, worldwide, individuals with these compound thrombophilias, predominantly through mailing members of the International Society on Thrombosis and Haemostasis. Physicians were sent a clinical questionnaire. Confirmatory copies of the genetic results were obtained. One hundred individuals were enrolled; 58% were female. Seventy-one individuals had a venous thrombosis (includes superficial and deep vein thrombosis, and pulmonary embolism), 4 had an arterial thrombosis and 6 had both. Nineteen individuals had never had a thrombotic event. Thrombosis-free survival curves demonstrated that 50% of individuals had experienced a thrombotic event by 35 yrs of age, while 50% had a first venous thromboembolic event (VTE; includes all venous thrombosis except superficial thrombosis) by 41 yrs of age; 38.2% of first VTEs were unprovoked. 37% of patients had at least one VTE recurrence. Seventy percent of first pregnancies carried to term and not treated with anticoagulation were thrombosis-free. In conclusion, patients with these rare compound thrombophilias are not exceedingly thrombogenic, even though they have a substantial risk for VTE., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Cerebral venous thrombosis (CVT) is a rare thrombotic disorder involving the cerebral veins and dural sinuses. In contrast to more common sites of venous thromboembolism (VTE), such as the legs and lungs, CVT mainly affects young adults and children, and women are affected three times more often than men. Although presenting symptoms are variable, headache is usually the first symptom, often in combination with focal neurologic deficits and epileptic seizures. The primary therapy for CVT consists of heparin followed by oral anticoagulation for at least 3 to 6 months. The mortality in the acute phase is 5 to 10% and a substantial proportion of survivors suffer from long-term disabilities. A large number of risk factors have been linked to CVT, although the scientific evidence for an association varies considerably between risk factors. Some risk factors, such as hereditary thrombophilia, correspond with risk factors for more common sites of VTE, whereas others, such as head trauma, are specific to CVT. In most patients, at least one risk factor can be identified. In this review, we provide an overview of the risk factors for CVT., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Hereditary thrombophilia is associated with a slightly increased risk of arterial thromboembolism (ATE). Whether hereditary thrombophilia interacts with traditional cardiovascular risk factors on the risk of ATE has yet to be established., Methods and Results: A total of 1891 individuals belonging to 4 family cohorts from the Netherlands were included in the analyses. Five hereditary thrombophilic defects, including factor V Leiden, prothrombin G20210A defect, and deficiencies of the natural anticoagulants (ie, antithrombin, protein C, and protein S), were assessed, and data on risk factors and previous ATE were collected. Thrombophilia was associated with elevated risk of ATE (hazard ratio =1.74, 95% confidence interval, 1.18-2.58; P=0.005). Overall, the association of thrombophilia with ATE tended to be stronger in the presence of traditional cardiovascular risk factors, especially the synergistic effect of thrombophilia with diabetes mellitus was striking (hazard ratio of thrombophilia-ATE association was 1.41 in nondiabetics versus 8.11 in diabetics). Moreover, the association of thrombophilia with ATE tended to be stronger in females and before the age of 55 years as compared with males and individuals >55 years of age, respectively., Conclusions: Thrombophilia is associated with ATE. This association may be stronger in the presence of traditional cardiovascular risk factors in particular in individuals with diabetes mellitus. Future studies on thrombophilia-ATE risk should focus on high-risk populations with high prevalence of traditional cardiovascular risk factors., (© 2016 American Heart Association, Inc.)

Background: A large number of studies have shown an association between inherited thrombophilia and recurrent miscarriage. It has been hypothesized that anticoagulant therapy might reduce the number of miscarriages and stillbirth in these women. In the absence of randomized controlled trials evaluating the efficacy of anticoagulant therapy in women with inherited thrombophilia and recurrent miscarriage, a randomized trial with adequate power that addresses this question is needed. The objective of the ALIFE2 study is therefore to evaluate the efficacy of low-molecular-weight heparin (LMWH) in women with inherited thrombophilia and recurrent miscarriage, with live birth as the primary outcome., Methods/design: Randomized study of LMWH plus standard pregnancy surveillance versus standard pregnancy surveillance alone., Study Population: pregnant women of less than 7 weeks' gestation, and confirmed inherited thrombophilia with a history of 2 or more miscarriages or intra-uterine fetal deaths, or both., Setting: multi-center study in centers from the Dutch Consortium of Fertility studies; centers outside the Netherlands are currently preparing to participate., Intervention: LMWH enoxaparin 40 mg subcutaneously once daily started prior to 7 weeks gestational age plus standard pregnancy surveillance or standard pregnancy surveillance alone. Main study parameters/endpoints: the primary efficacy outcome is live birth. Secondary efficacy outcomes include adverse pregnancy outcomes, such as miscarriage, pre-eclampsia, syndrome of hemolysis, elevated liver enzymes and low platelets (HELLP syndrome), fetal growth restriction, placental abruption, premature delivery and congenital malformations. Safety outcomes include bleeding episodes, thrombocytopenia and skin reactions., Discussion: After an initial period of slow recruitment, the recruitment rate for the study has increased. Improved awareness of the study and acknowledgement of the need for evidence are thought to be contributing to the improved recruitment rates. We aim to increase the number of recruiting centers in order to increase enrollment into the ALIFE2 study. The study website can be accessed via www.ALIFE2study.org., Trial Registration: The ALIFE2 study was registered on 19 March 2012 under registration number NTR3361.

The etiology of pediatric venous thromboembolic disease (VTE) is multifactorial, and in most children, 1 or more clinical risk factors are present. In addition, inherited thrombophilic disorders contribute to the development of pediatric VTE. In this review, the role of inherited thrombophilic disorders in the development of pediatric VTE, as well as the benefits and limitations of thrombophilia testing, will be discussed., (© 2015 by The American Society of Hematology.)

Background: Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the chance of live birth in subsequent pregnancies in women with unexplained recurrent miscarriage, with or without inherited thrombophilia., Objectives: To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia., Search Methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 October 2013) and scanned bibliographies of all located articles for any unidentified articles., Selection Criteria: Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on live birth in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin (UFH), and low molecular weight heparin (LMWH) for the prevention of miscarriage. One treatment could be compared with another or with no-treatment (or placebo)., Data Collection and Analysis: Two review authors (PJ and SK) assessed the studies for inclusion in the review and extracted the data. If necessary they contacted study authors for more information. We double checked the data., Main Results: Nine studies, including data of 1228 women, were included in the review evaluating the effect of either LMWH (enoxaparin or nadroparin in varying doses) or aspirin or a combination of both, on the chance of live birth in women with recurrent miscarriage, with or without inherited thrombophilia. Studies were heterogeneous with regard to study design and treatment regimen and three studies were considered to be at high risk of bias. Two of these three studies at high risk of bias showed a benefit of one treatment over the other, but in sensitivity analyses (in which studies at high risk of bias were excluded) anticoagulants did not have a beneficial effect on live birth, regardless of which anticoagulant was evaluated (risk ratio (RR) for live birth in women who received aspirin compared to placebo 0.94, (95% confidence interval (CI) 0.80 to 1.11, n = 256), in women who received LMWH compared to aspirin RR 1.08 (95% CI 0.93 to 1.26, n = 239), and in women who received LMWH and aspirin compared to no-treatment RR 1.01 (95% CI 0.87 to 1.16) n = 322).Obstetric complications such as preterm delivery, pre-eclampsia, intrauterine growth restriction and congenital malformations were not significantly affected by any treatment regimen. In included studies, aspirin did not increase the risk of bleeding, but treatment with LWMH and aspirin increased the risk of bleeding significantly in one study. Local skin reactions (pain, itching, swelling) to injection of LMWH were reported in almost 40% of patients in the same study., Authors' Conclusions: There is a limited number of studies on the efficacy and safety of aspirin and heparin in women with a history of at least two unexplained miscarriages with or without inherited thrombophilia. Of the nine reviewed studies quality varied, different treatments were studied and of the studies at low risk of bias only one was placebo-controlled. No beneficial effect of anticoagulants in studies at low risk of bias was found. Therefore, this review does not support the use of anticoagulants in women with unexplained recurrent miscarriage. The effect of anticoagulants in women with unexplained recurrent miscarriage and inherited thrombophilia needs to be assessed in further randomised controlled trials; at present there is no evidence of a beneficial effect.

The incidence of venous thromboembolism (VTE) is two-fold higher in women than in men during reproductive age, which is likely explained by the use of hormonal contraceptives and by pregnancy in this phase of life. After adjustment for these factors, men have a two-fold higher risk of developing a first VTE compared with women, which is in line with earlier observations that men have a two-fold higher risk of recurrent VTE. These findings indicate that the intrinsic risk of VTE is higher in men than in women. Hormonal contraceptives increase the risk of VTE and the risk varies per type, dose, and administration route. In women with a high baseline risk of VTE, avoidance of some hormonal contraceptives should be considered, as well as thrombosis prophylaxis during pregnancy. Presence of hereditary thrombophilia increases the risk of a first VTE episode. This review focuses on the differences in risk of VTE between men and women, hormonal risk factors for women, and how these interact with common types of hereditary thrombophilia., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

BACKGROUND Although an association between thrombophilia and pregnancy loss has been observed in many studies, little is known about the pathophysiological mechanisms behind this association. Considering the association between thrombophilia and pregnancy loss, the efficacy of antithrombotic therapy for women with pregnancy loss (with or without thrombophilia) has been studied for the past 30 years. METHODS We performed a comprehensive review of the literature on the strength of the association between thrombophilia and pregnancy loss, the pathophysiological mechanisms and the efficacy of antithrombotic therapy to increase the chance of live birth. RESULTS The association between pregnancy loss and thrombophilia varies according to the type of thrombophilia (e.g. antiphospholipid syndrome versus forms of inherited thrombophilia) and according to the type of pregnancy loss (single versus recurrent pregnancy loss and early versus late pregnancy loss). Thrombophilia may induce thrombosis in decidual vessels or impair placentation through hypercoagulability and inflammation, but these hypotheses need further verification. For women with antiphospholipid syndrome, evidence from small-sized trials suggests a beneficial effect of antithrombotic therapy but additional randomized controlled trials are essential to confirm this. Whether antithrombotic therapy increases the chance of live birth in women with inherited thrombophilia is unknown. Recent randomized controlled trials have consistently shown that antithrombotic therapy does not increase the chance of live birth in women with unexplained recurrent miscarriage. CONCLUSIONS There are large gaps in knowledge and a lack of evidence for treatment of women with pregnancy loss with thrombophilia. To provide a solid base for clinical practice, further studies on the role of coagulation in reproduction, as well as international collaborations in randomized controlled trials of antithrombotic therapy in women with pregnancy loss, and antiphospholipid syndrome or inherited thrombophilia are urgently needed.

Cerebral venous thrombosis (CVT) is a rare manifestation of venous thromboembolism (VTE) and stroke. The aim of our systematic review was to provide an updated summary of the strength of association between CVT and thrombophilia and to explore the relevance of thrombophilia for recurrence of CVT or other VTE, or other outcome variables. MEDLINE (via PubMed), EMBASE (via Ovid), and CENTRAL were systematically searched, including references of retrieved articles. Cohort studies of ≥ 40 patients and case-control studies comparing the prevalence of thrombophilia in patients with CVT and unrelated controls were eligible. Two reviewers independently selected studies, assessed quality, and extracted data. A meta-analysis was performed for high quality case-control studies with unselected cases and healthy controls. Odds ratios with 95% confidence intervals were calculated and pooled. We included 23 cohort studies and 33 case-control studies. A significant association was demonstrated between CVT and all inherited thrombophilic factors, as well as increased levels of homocysteine. Inconclusive results were found on the relevance of thrombophilia for recurrent CVT or other VTE. Although there is a strong association between CVT and thrombophilia, the clinical relevance of thrombophilia testing in patients with CVT seems limited, similarly to other forms of VTE., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: Tests for thrombophilia are being performed on a large scale in people after venous thromboembolism (VTE) even though the benefits of testing are still subject to debate. The most important benefit would be a reduction in the risk of recurrent VTE due to the use of additional prophylactic measures. This is an update of a review first published in 2009., Objectives: The objective of this review was to assess the benefit of testing for thrombophilia after VTE in terms of risk reduction of recurrent VTE., Search Methods: For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched May 21 2012) and CENTRAL (2012, Issue 5). The authors searched MEDLINE and EMBASE., Selection Criteria: Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared the rate of recurrent VTE in participants with VTE who were tested for thrombophilia with the rate in participants with VTE who were not tested were eligible., Data Collection and Analysis: We planned to extract data from identified studies using data extraction forms., Main Results: No studies were included because no RCTs or CCTs could be identified., Authors' Conclusions: There are currently no randomized controlled trials or controlled clinical trials that have assessed the benefit(s) of testing for thrombophilia on the risk of recurrent VTE.

Venous thromboembolism (VTE) is a leading cause of maternal mortality and morbidity during pregnancy in developed countries. The incidence of VTE per pregnancy-year increases about 4-fold during pregnancy and at least 14-fold during the puerperium. Risk factors include a personal history of VTE, presence of inherited or acquired thrombophilia, a family history of VTE and general medical conditions, such as immobilisation, overweight, varicose veins, some haematological diseases and inflammatory disorders. VTE is considered potentially preventable with the prophylactic administration of anticoagulants, but there are no high quality randomized clinical trials that compared different strategies of thromboprophylaxis in pregnant women. Balancing the absolute risk of VTE against the risks of exposure to anticoagulants, this review provides advice regarding which women may benefit from thromboprophylaxis during and after pregnancy., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: The use of anticoagulant therapy during pregnancy is challenging because of the potential for both fetal and maternal complications. This guideline focuses on the management of VTE and thrombophilia as well as the use of antithrombotic agents during pregnancy., Methods: The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement., Results: We recommend low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women instead of unfractionated heparin (Grade 1B). For pregnant women with acute VTE, we suggest that anticoagulants be continued for at least 6 weeks postpartum (for a minimum duration of therapy of 3 months) compared with shorter durations of treatment (Grade 2C). For women who fulfill the laboratory criteria for antiphospholipid antibody (APLA) syndrome and meet the clinical APLA criteria based on a history of three or more pregnancy losses, we recommend antepartum administration of prophylactic or intermediate-dose unfractionated heparin or prophylactic low-molecular-weight heparin combined with low-dose aspirin (75-100 mg/d) over no treatment (Grade 1B). For women with inherited thrombophilia and a history of pregnancy complications, we suggest not to use antithrombotic prophylaxis (Grade 2C). For women with two or more miscarriages but without APLA or thrombophilia, we recommend against antithrombotic prophylaxis (Grade 1B)., Conclusions: Most recommendations in this guideline are based on observational studies and extrapolation from other populations. There is an urgent need for appropriately designed studies in this population.

Approximately 1-5% of women trying to conceive experience recurrent miscarriage, and in 50% of these women, the cause of the preceding miscarriages is unknown. Inherited thrombophilias such as factor V Leiden mutation, prothrombin gene mutation (PT 20210A), and deficiencies of natural anticoagulants protein C, protein S, and antithrombin are associated with recurrent miscarriage. Knowledge of the association between inherited thrombophilia and recurrent miscarriage and of potential treatment options for improving chances of a live birth could tempt physicians to test for inherited thrombophilia in women with recurrent miscarriage. However, the strength of the association between inherited thrombophilia and recurrent miscarriage is not very strong, and more importantly, no evidence indicates that the use of anticoagulants improves the chance of live birth in these women. With the current state of evidence, testing for inherited thrombophilia should not lead to altered clinical management and therefore, should not be performed routinely in women with recurrent miscarriage but only in the context of scientific studies., (© Thieme Medical Publishers.)

Inherited thrombophilia is defined as a genetically determined tendency to develop venous thromboembolism. In children, inherited thrombophilia contributes to the development of pediatric thromboembolic disease. As a consequence, pediatric hematologists are increasingly requested to test thrombophilia in pediatric patients with thrombosis or asymptomatic children from thrombophilic families. This article reviews the benefits and limitations of testing for thrombophilic disorders, for example, factor V Leiden, prothrombin mutation, and deficiencies of antithrombin, protein C, or protein S in childhood., (© Thieme Medical Publishers.)

Thrombophilia can be identified in about half of all patients presenting with VTE. Testing has increased tremendously for various indications, but whether the results of such tests help in the clinical management of patients has not been settled. I use evidence from observational studies to conclude that testing for hereditary thrombophilia generally does not alter the clinical management of patients with VTE, with occasional exceptions for women at fertile age. Because testing for thrombophilia only serves limited purpose this should not be performed on a routine basis.

Thrombophilia is found in many patients presenting with venous thromboembolism (VTE). However, whether the results of such tests help in the clinical management of such patients has not been determined. Thrombophilia testing in asymptomatic relatives may be useful in families with antithrombin, protein C, or protein S deficiency or homozygosity for factor V Leiden, but is limited to women who intend to become pregnant or who would like to use oral contraceptives. Careful counseling with knowledge of absolute risks helps patients in making an informed decision in which their own preferences can be taken into account. Observational studies show that patients who have had VTE and have thrombophilia are at most at a slightly increased risk for recurrence. In an observational study, the risk of recurrent VTE in patients who had been tested for inherited thrombophilia was not lower than in patients who had not been tested. In the absence of trials comparing routine and prolonged anticoagulant treatment in patients testing positive for thrombophilia, testing for such defects to prolong anticoagulant therapy cannot be justified. Diagnosing antiphospholipid syndrome (APS) in women with recurrent miscarriage usually leads to treatment with aspirin and low-molecular-weight heparin (LMWH), although the evidence to support this treatment is limited. Because testing for thrombophilia serves a limited purpose, this test should not be performed on a routine basis.

Thrombophilia screening is controversial. In a retrospective family cohort, where probands had thrombosis and a thrombophilic defect, 2479 relatives were tested for thrombophilia. In antithrombin-, protein C-, and protein S-deficient relatives, annual incidences of venous thrombosis were 1.77% (95% CI, 1.14-2.60), 1.52% (95% CI, 1.06-2.11), and 1.90% (95% CI, 1.32-2.64), respectively, at a median age of 29 years and a positive family history of more than 20% symptomatic relatives. In relatives with factor V (FV) Leiden, prothrombin 20210G>A, or high FVIII levels, these were 0.49% (95% CI, 0.39-0.60), 0.34% (95% CI, 0.22-0.49), and 0.49% (95% CI, 0.41-0.51), respectively. High FIX, FXI, and TAFI, and hyperhomocysteinemia were not independent risk factors. Annual incidence of major bleeding in antithrombin-, protein C-, or protein S-deficient relatives on anticoagulants was 0.29% (95% CI, 0.03-1.04). Cumulative recurrence rates in relatives with antithrombin, protein C, or protein S deficiency were 19% at 2 years, 40% at 5 years, and 55% at 10 years. In relatives with FV Leiden, prothrombin 20210G>A, or high levels FVIII, these were 7%, 11%, and 25%, respectively. Considering its clinical implications, thrombophilia testing should address hereditary deficiencies of antithrombin, protein C, and protein S in patients with first venous thrombosis at young age and/or a strong family history of venous thrombosis.

Despite knowledge of various inherited risk factors associated with venous thromboembolism (VTE), no definite cause can be found in about 50% of patients. The lack of an intermediate phenotype in VTE impedes the discovery of new familial risk factors. We set out to define an intermediate phenotype for VTE by performing global coagulation analyses in unexplained thrombophilic families. Families were selected through a proband with VTE but without one of the known thrombophilic defects and at least one 1st or two 2nd degree family members with VTE. Clinical data were collected using a standardized questionnaire. Blood samples were collected for overall haemostasis assays (i.e. thrombin generation time [TGT], endogenous thrombin potential [ETP], prothrombin fragment 1+2 [F1+2] and activated protein C-sensitivity ratio [APC-sr] and clot lysis time [CLT]). Data were analysed using logistic regression. Coagulation assays were performed in 353 individuals of whom 41 (12%) had a history of VTE; these belonged to 17 thrombophilic families. Of the tested variables only the ETP was associated with VTE (odds ratio [OR] 1.03 for each % increase, 95% confidence interval [CI] 1.01-1.05). However, the relatively low number of cases does not firmly exclude the other assays as candidate intermediate phenotypes for venous thrombosis. We found that an increased ETP may serve as an intermediate phenotype for VTE and may be used to discover novel inherited risk factors by genetic linkage analysis.

Background: Since hypercoagulability might result in recurrent miscarriage, anticoagulant agents could potentially increase the live-birth rate in subsequent pregnancies in women with either inherited thrombophilia or unexplained recurrent miscarriage., Objectives: To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two miscarriages without apparent causes other than inherited thrombophilia., Search Strategy: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2008), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 1), MEDLINE (January 1966 to March 2007), and EMBASE (1980 to March 2007). We scanned bibliographies of all located articles for any unidentified articles., Selection Criteria: Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on the live-birth rate in women with a history of at least two miscarriages (up to 20 weeks of amenorrhoea) without apparent causes other than inherited thrombophilia were eligible. Interventions included aspirin, unfractionated heparin, and low molecular weight heparin for the prevention of miscarriage. One treatment could be compared with another or with placebo., Data Collection and Analysis: Two authors assessed the trials for inclusion in the review and extracted the data. We double checked the data., Main Results: Two studies (189 participants) were included in the review. In one study, 54 pregnant women with recurrent miscarriage (RM) but no detectable anticardiolipin antibodies were randomised to low-dose aspirin or placebo. RM was defined as three or more consecutive miscarriages (occurring before 22 weeks' gestational age (based on last menstrual period)). Similar live-birth rates were observed with aspirin and placebo, both 81% (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.78 to 1.29). In the other study, 107 women with consecutive recurrent miscarriage without any apparent cause and no hereditary thrombophilia were randomised between enoxaparin and aspirin. Here RM was stated as three or more consecutive first trimester miscarriages or at least two consecutive second trimester miscarriages. Similar live birth rates were observed with enoxaparin and aspirin, respectively 82% and 84% (RR 0.97, 95% CI 0.81 to 1.16)., Authors' Conclusions: There is a paucity in studies on the efficacy and safety of aspirin and heparin in women with a history of at least two miscarriages without apparent causes other than inherited thrombophilia. The two reviewed trials studied different treatments and only one study was placebo-controlled. Neither of the studies showed a benefit of one treatment over the other. Therefore, the use of anticoagulants in this setting is not recommended. However, large randomised placebo-controlled trials are still urgently needed.

Background: Tests for thrombophilia are being performed on a large scale in people after venous thromboembolism (VTE) even though the benefits of testing are still subject to debate. The most important benefit would be a reduction in the risk of recurrent VTE due to the use of additional prophylactic measures., Objectives: The objective of this review was to assess the benefit of testing for thrombophilia after VTE in terms of risk reduction of recurrent VTE., Search Strategy: The Cochrane Peripheral Vascular Diseases (PVD) Group searched their Trials Register (last searched 15 October 2008) and CENTRAL (last searched The Cochrane Library 2008, Issue 4). We searched MEDLINE, EMBASE, and reference lists., Selection Criteria: Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared the rate of recurrent VTE in participants with VTE who were tested for thrombophilia with the rate in participants with VTE who were not tested were eligible., Data Collection and Analysis: We planned to extract data from identified studies using data extraction forms., Main Results: No studies were included because no RCTs or CCTs could be identified., Authors' Conclusions: There are currently no randomized controlled trials or controlled clinical trials that have assessed the benefit(s) of testing for thrombophilia on the risk of recurrent VTE.

Thrombophilia can be identified in about half of all patients presenting with venous thrombosis. Testing has increased tremendously for various indications, but whether the results of such tests help in the clinical management of patients has not been settled. Here, we review the most commonly tested thrombophilic abnormalities, i.e. protein C, protein S, and antithrombin deficiencies, the F5 R506Q (factor V Leiden) and F2 G20210A (prothrombin G20210A) mutations, and elevated levels of coagulation factor VIII, and their association with venous and arterial thrombosis as well as pregnancy complications. We conclude that testing for hereditary thrombophilia generally does not alter the clinical management of patients with venous or arterial thrombosis or pregnancy complications. Because testing for thrombophilia only serves limited purpose this should not be performed on a routine basis.

The NOSTRADAMUS study (ISRCTN07836779) was prematurely terminated due to low inclusion rates. There were several causes for this low inclusion: delay of approval by medical ethics committees, competition with industry-initiated intervention studies with a higher financial compensation, and the lack of study staff and allowance of expenses. We advise restraint with respect to testing for thrombophilia in patients with a first deep vein thrombosis or pulmonary embolism, as the benefit of this procedure has yet to be demonstrated.

Background: Inherited thrombophilia is only weakly associated with recurrence in patients with a first venous thrombosis (VT). In spite of this, thrombophilia testing is often performed in these patients. Positive results may influence patient management such as prolonged anticoagulant treatment or intensified prophylaxis in high-risk situations., Objective: To investigate whether thrombophilia testing reduces the risk of recurrent VT by virtue of these management alterations., Methods: From a large case-control study of patients (MEGA study), aged 18-70 years, with a first VT between 1999 and 2004, we selected 197 patients who had had a recurrence during follow-up. We compared the incidence of thrombophilia testing to that of a control cohort of 324 patients. We calculated the odds ratio (OR) for recurrent thrombosis in tested vs. non-tested patients. Only patients who were tested before recurrence were regarded as tested. All first and recurrent thrombotic events were objectively confirmed., Results: Thrombophilia tests were performed in 35% of cases and in 30% of controls. The OR for recurrence was 1.2 [95% confidence interval (CI) 0.9-1.8] for tested vs. non-tested patients. After correction for age, sex, family history, geographic region, presence of clinical risk factors, and year of first VT, the OR remained unchanged., Discussion: Thrombophilia testing in patients with a first VT does not reduce the incidence of recurrence in clinical practice.

Inherited thrombophilias are not yet established as a cause of placenta-mediated pregnancy complications, such as fetal growth restriction, preeclampsia, abruption, and pregnancy loss. An inherited thrombophilia is only one of many factors that lead to development of these diseases and is unlikely to be the unique factor that should drive management in subsequent pregnancies. The paucity of evidence for benefit, coupled with a small potential for harm, suggests that low molecular weight heparin should be considered an experimental drug for these indications until data from controlled trials are published. At present, women with a history of placenta-mediated pregnancy complications, with or without a thrombophilia, should be followed closely without routine prophylactic low molecular weight heparin other than for prevention of venous thromboembolism in limited circumstances.

Background: Nowadays, large numbers of patients are tested for thrombophilia, even though the benefits of this strategy remain unclear. A potential disadvantage of this predominantly genetic testing is the psychological impact, including fear, depression and worry., Objectives: To systematically review studies that determined the nature and extent of the psychological impact of testing for thrombophilia., Patients/methods: We searched the MEDLINE data base (1966-2008), the EMBASE data base (1985-2008) and the PsychInfo data base (1806-2008) for relevant trials, without language restrictions. Bibliographies of relevant articles were scanned for additional articles. We reviewed all relevant studies that focused on the psychological impact of testing for thrombophilia. Only full papers of studies that included 15 patients or more were considered eligible for this review. Two reviewers independently extracted data and assessed quality., Results: Six studies fulfilled the eligibility criteria. As these studies varied appreciably in methodology, the pooling of data was not possible. Studies of psychological impact of genetic testing for thrombophilia report few negative results, although most assessments were limited to short-term follow-up, or lacked methodological accuracy., Conclusions: No valid conclusions can be drawn about the psychological impact of genetic testing in patients based on the current available literature. Given the large number of patients that are being exposed to testing for thrombophilia, and the uncertain benefits, there is an urgent need for more uniformity in the measurement of the psychological impact of thrombophilia testing.

High levels of thrombin-activatable fibrinolysis inhibitor (TAFI) are a supposed risk factor for thrombosis. However, results from previous studies are conflicting. We assessed the absolute risk of venous and arterial thromboembolism in subjects with high TAFI levels (>126 U/dl) versus subjects with normal levels, and the contribution of other concomitant thrombophilic defects. Relatives from four identical cohort studies in families with either deficiencies of antithrombin, protein C or protein S, prothrombin 20210A, high factor VIII levels, or hyperhomocysteinemia were pooled. Probands were excluded. Of 1,940 relatives, 187 had high TAFI levels. Annual incidences of venous thromboembolism were 0.23% in relatives with high TAFI levels versus 0.26% in relatives with normal TAFI levels (adjusted relative risk [RR] 0.8; 95% confidence interval [CI], 0.5-1.3). For arterial thrombosis these were 0.31% versus 0.23% (adjusted RR 1.4; 95% CI, 0.9-2.2). High levels of factor VIII, IX and XI were observed more frequently in relatives with high TAFI levels. Only high factor VIII levels were associated with an increased risk of venous and arterial thrombosis, independently of TAFI levels. None of these concomitant defects showed interaction with high TAFI levels. High TAFI levels were not associated with an increased risk of venous and arterial thromboembolism in thrombophilic families.

In the last decades, the knowledge on the etiology of venous thromboembolism (VTE) has increased tremendously. In approximately half of patients presenting with VTE, one or more thrombophilic defects can be identified. This has led to widespread testing for thrombophilia, despite the fact that, at present, it is unclear whether this should have therapeutic consequences. Here we review the currently established hereditary and acquired thrombophilic defects, and focus on the pros and cons of testing in the setting of VTE. Thrombophilia is defined as a disorder associated with an increased tendency to venous thromboembolism (VTE). Thrombophilia can be acquired, such as in patients with cancer, or congenital, in which case a defect in the coagulation system is hereditary. Egeberg was the first to use the term thrombophilia in 1965, when he described a Norwegian family that had a remarkable tendency to VTE, based on a deficiency of antithrombin. Since then, various laboratory abnormalities, both hereditary and acquired, have been discovered that increase the risk of VTE. This article reviews the currently established thrombophilic abnormalities and discusses the potential usefulness and implications of testing for thrombophilia.

As homocysteine-lowering treatment has not reduced the risk of recurrent thrombosis in recent clinical trials, we hypothesized that mild hyperhomocysteinaemia is an epiphenomenon or associated with a low absolute risk of thrombosis. In this retrospective study, we enrolled 478 evaluable first-degree relatives of consecutive patients with venous thrombosis or premature atherosclerosis, and hyperhomocysteinemia. Absolute risks of thrombosis and effects of concomitant thrombophilic defects were compared. Relative risks were adjusted for clustering in families, age, sex, and atherosclerotic risk factors, where appropriate. Annual incidence of venous thrombosis was 0.16% (95% confidence interval [CI], 0.08-0.30) in hyperhomocysteinemic relatives versus 0.11% (CI, 0.05-0.20) in normohomocysteinemic relatives; adjusted relative risk 1.6 (CI, 0.6-4.5). Annual incidences of arterial thrombosis were 0.34% (CI, 0.21-0.52) and 0.24% (CI, 0.15-0.37) in hyperhomocysteinemic and normohomocysteinemic relatives, respectively; adjusted relative risk 1.5 (CI, 0.6-3.5). Concomitance of multiple thrombophilic risk factors increased the risk of venous thrombosis in hyperhomocysteinemic relatives 20 fold, but a comparable effect was demonstrated in normohomocysteinemic relatives. We conclude that hyperhomocysteinaemia is associated with a low absolute risk of venous and arterial thrombosis. Concomitant thrombophilic defects are probably main determinants on the risk of venous thrombosis, rather than hyperhomocysteinaemia itself.

Both acquired and inherited thrombophilia is associated with an increased risk of pregnancy failure (i.e. sporadic and recurrent miscarriage, late fetal loss), as well as hypertensive pregnancy complications such as pre-eclampsia and HELLP syndrome. The question of whether this relationship can be considered causal is rather philosophical. For practical purposes, the consistency and strengths of associations, potential mechanisms and, most importantly, the possibility to intervene with anticoagulants are reviewed. Relevant methodological issues in the case of thrombophilia and pregnancy complications consist of differences between observational and experimental research and quality issues in randomized controlled trials. The mechanisms associating thrombophilia and pregnancy complications are likely to involve effects on trophoblast differentiation rather than mere hypercoagulability. Therapeutic options comprise aspirin as well as (low molecular weight) heparin. For women with antiphospholipid antibody syndrome, this treatment is often suggested although the evidence is limited. For women with inherited thrombophilia and unexplained recurrent pregnancy loss, at present there is no evidence supporting treatment. Observational research is hampered by severe methodological flaws or inconsistent results. Two published randomized trials have not used an adequate comparator (i.e. no treatment or placebo). Currently, randomized controlled trials with no treatment or placebo are being carried out and results should be awaited before implementing a potentially harmful intervention in pregnant women with inherited thrombophilia and a history of pregnancy complications.

Heritable thrombophilia is associated with an increased risk for pregnancy failure, defined as sporadic and recurrent miscarriage, late fetal loss, and other vascular pregnancy complications such as preeclampsia and intrauterine growth retardation. The pathogenesis is likely to include effects on trophoblast differentiation and not solely hypercoagulability. This is in line with the observation that most recurrent miscarriages occur early. Therapeutic options include aspirin as well as low-molecular-weight heparin. However, in women with heritable thrombophilia and unexplained recurrent pregnancy loss, evidence is not available as published trials have not used an adequate comparator (no treatment or placebo). Currently, randomized controlled trials with no treatment or placebo are being carried out and results should be awaited before implementing a potentially harmful intervention in pregnant women with heritable thrombophilia and a history of pregnancy failure. Both infertility and pregnancy failure are extremely distressing for couples with the desire to have children. Pregnancy failure comprises (recurrent) early miscarriage, as well as late pregnancy loss. The role of heritable thrombophilia in pregnancy failure is reviewed, with a focus on recurrent miscarriage, in terms of epidemiology, etiology, and potential therapeutic implications.

Many inherited thrombophilias have been detected and the pathophysiologic insight has increased tremendously during the last decades. Despite, however, the overwhelming observational evidence on the association between inherited thrombophilia and several women's health issues, including VTE, thus far the implications for clinical practice are uncertain. Although there is firm epidemiologic evidence that is helpful in counseling women who have inherited thrombophilia to prevent a first or recurrent VTE, the uncertainty is particularly present for women who have other pregnancy complications, such as recurrent pregnancy loss and pre-eclampsia. For this group, well-designed placebo-controlled trials to assess the harm-benefit ratio are urgently needed.

In more than half of the couples with recurrent miscarriage, no underlying cause can be found. Both acquired and hereditary risk factors for venous thrombosis, i.e. thrombophilia, constitute an aetiologic factor in a minority of patients with recurrent miscarriage. In women with a diagnosis of antiphospholipid antibody syndrome, treatment with low-dose acetylsalicylic acid and low-molecular-weight heparin has been shown by a valid randomised controlled trial to improve the results of a subsequent pregnancy. However, it is unknown whether anticoagulant treatment of women with recurrent miscarriage and hereditary risk factors for thrombophilia improves the outcome of a subsequent pregnancy.

Background: Since hypercoagulability might result in recurrent pregnancy loss, anticoagulant agents could potentially increase the live-birth rate in subsequent pregnancies in women with either inherited thrombophilia or unexplained pregnancy loss., Objectives: To evaluate the efficacy and safety of anticoagulant agents, such as aspirin and heparin, in women with a history of at least two spontaneous miscarriages or one later intrauterine fetal death without apparent causes other than inherited thrombophilias., Search Strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register (March 2004), the Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2004), MEDLINE (January 1966 to March 2004), and EMBASE (1980 to March 2004). We scanned bibliographies of all located articles for any unidentified articles., Selection Criteria: Randomised and quasi-randomised controlled trials that assessed the effect of anticoagulant treatment on the live-birth rate in women with a history of at least two spontaneous miscarriages or one later intrauterine fetal death without apparent causes other than inherited thrombophilias were eligible. Interventions included aspirin, unfractionated heparin, and low molecular weight heparin for the prevention of birth loss. One treatment could be compared with another or with placebo., Data Collection and Analysis: Two authors assessed the trials for inclusion in the review and extracted the data. Data were entered into the Review Manager software and double checked., Main Results: Two studies (242 participants) were included in the review and for both of them data were extracted for the subgroups of women fulfilling the inclusion criteria of the review. In one study, 54 pregnant women with recurrent spontaneous abortion without detectable anticardiolipin antibodies were randomised to low-dose aspirin or placebo. Similar live-birth rates were observed with aspirin and placebo (relative risk (RR) 1.00, 95% confidence interval (CI) 0.78 to 1.29). In another study, a subgroup of 20 women who had had a previous fetal loss after the 20th week and had a thrombophilic defect were randomised to enoxaparin or aspirin. Enoxaparin treatment resulted in an increased live-birth rate, as compared to low-dose aspirin, RR 10.00, 95% CI 1.56 to 64.20)., Authors' Conclusions: The evidence on the efficacy and safety of thromboprophylaxis with aspirin and heparin in women with a history of at least two spontaneous miscarriages or one later intrauterine fetal death without apparent causes other than inherited thrombophilias is too limited to recommend the use of anticoagulants in this setting. Large, randomised, placebo-controlled trials are urgently needed.

Venous thromboembolism, which includes deep vein thrombosis and pulmonary embolism, is the result of an imbalance among procoagulant, anticoagulant and profibrinolytic processes. This imbalance reflects a complex interplay between genetic and environmental or acquired risk factors. Genetic thrombophilic defects influence the risk of a first episode of thrombosis. How these defects influence the risk of recurrence in patients whose first episode of venous thromboembolism was unprovoked is less certain. Thus, when anticoagulants are stopped, patients with unprovoked venous thromboembolism have a risk of recurrence of at least 7% to 10% per year, even in the absence of an underlying thrombophilic defect. Consequently, there is a trend toward longer durations of anticoagulation therapy for these patients, which is problematic given the limitation of existing anticoagulants. This chapter provides an overview of the thrombophilic defects and how they influence the risk of venous thromboembolism. The chapter also details advances in anticoagulant therapy, focusing on new inhibitors of factor Xa and thrombin. In Section I, Dr. Saskia Middeldorp describes the various thrombophilic defects and reviews their relative importance in the pathogenesis of a first episode of venous thromboembolism. She then discusses the influence of these defects on the risk of recurrent thrombotic events in patients with unprovoked venous thromboembolism and in those whose thrombosis occurred in association with a known risk factor, such as surgery. In Section II, Dr. William Geerts reviews the pharmacology of new parenteral and oral factor Xa inhibitors and describes the results of the Phase II and III clinical trials with these agents. He then provides perspective on the potential advantages and drawbacks of these drugs for the prevention and treatment of venous thromboembolism. In Section III, Dr. John Heit focuses on direct thrombin inhibitors. He discusses their mechanism of action and compares and contrasts their pharmacological profiles prior to describing the results of Phase II and III clinical trials. Dr. Heit then provides perspective on the potential advantages and limitations of these drugs relative to existing anticoagulants.

Acquired and inherited thrombophilic factors increase the risk for (recurrent) venous thrombotic disease. However, little is known about the pathophysiological mechanisms causing these recurrences, or the persistence of thrombosis despite adequate treatment. Because residual thrombosis has been associated with a worse prognostic outcome, we performed an explorative study in order to investigate the prevalence of residual thrombotic lesions after anticoagulant treatment in patients with deep venous thrombosis. Thrombotic parameters as assessed by ultrasonography after a 12-week course of anticoagulants were used. Both thrombophilia in general and acquired thrombophilia in particular were found to be associated with the extent of residual thrombosis. Of the individual thrombophilic factors, protein C deficiency, prothrombin 20210A mutation, active malignant disease and lupus anticoagulant were associated with an increased risk of residual thrombotic mass. Patients with inherited thrombophilia did not differ from patients without any thrombophilic abnormality with regard to residual thrombotic mass [relative risk (RR) 1.3, 95% confidence interval (CI) 0.9-1.8], while acquired thrombophilic disorders increased the risk for residual thrombotic mass as compared to patients without any defect (RR 1.7, 95% CI 1.2-2.2). Although these results should be confirmed in a larger study, they might help us form hypotheses concerning why patients with thrombophilia are more prone to recurrent venous thromboembolic disease., (Copyright 2004 S. Karger AG, Basel.)