Family History Of Thromboembolism Research Articles

Unexpected find of native aortic leaflet thrombus during surgical myocardial revascularization.

A 47-year-old woman was referred from a regional hospital for surgical myocardial revascularization after non-ST-elevation myocardial infarction. Medical history reported dyslipidaemia, hypothyroidism, endometriosis surgery, and a family history of thromboembolism. Coronary angiogram and transthoracic echocardiography (TTE) performed 13 days earlier showed two-vessel coronary disease with severe stenosis of the left anterior descending (LAD), diagonal and marginal arteries, and preserved left-ventricular ejection fraction (LVEF = 55%) without significant valve disease. Intraoperative transoesophageal echocardiography (iTEE) showed a large mass attached to the aortic non-coronary leaflet and sinus of Valsalva (Panel A, white star), with reduced leaflet motion but no valvular hemodynamic dysfunction (Panel A). The mass was closely attached to and moving with the leaflet, but clear cleavage planes with the leaflet and the aortic root were observable (Panel A, white triangles). An organized thrombus secondary to an initial lesion by the catheter during coronary angiogram was suspected, and confirmed by the macroscopic and histological examination (Panel B). The thrombus was completely removed, and myocardial revascularization by sequential left internal thoracic graft to the diagonal and LAD as well as radial Y-graft to the marginal artery was performed. Post-bypass iTEE examination showed complete thrombus removal and normal motion of the leaflet (Panel C). On the basis of familial history of thrombus, our consultant haematologist recommended oral anticoagulation therapy with warfarin until results of blood coagulation disorder tests are obtained. The patient was discharged 6 days after surgery without significant post-operative complication.

Clinical and genetic features of Chinese pediatric patients with severe congenital protein C deficiency who first presented with purpura fulminans: A case series study and literature review

IntroductionPurpura fulminans (PF) is a hematological emergency that can be caused by severe congenital protein C (PC) deficiency. It has been rarely reported in the Chinese population. We aimed to characterize the clinical and genetic features of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. Materials and methodsTwelve pediatric patients were diagnosed with severe congenital PC deficiency with PF, which was diagnosed based on our hospital records and previous reports from 1988 to July 2021 in China. We evaluated the clinical and genetic features of these patients. ResultsNine patients (9/12, 75%) had onsets that were observed within the first 48 h after birth. Six patients had a family history of thromboembolism. There was no consanguinity. Other symptoms were intracranial thrombosis or hemorrhage (4, 33.3%), ocular lesions (2, 16.7%), gastrointestinal hemorrhage (2, 16.7%) and kidney infarction before birth (1, 8.3%). All but one of the patients (one case not detected) had a plasma PC activity of <10%. The genetic study indicated that in the eight patients with inherited PC deficiency, two were homozygous, five were compound heterozygous and one was heterozygous for PC deficiency. ConclusionThis is the first and largest case series of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. It has been shown that treatment with both fresh frozen plasma and anticoagulants is recommended when PC concentrate is not easily available, especially in developing countries.

Errors of antithrombotic therapy in management of pregnancy and childbirth after in vitro fertilization and transfer of two embryos

Thrombophilia might be the essential pathogenetic mechanism of thromboembolism associated with pregnancy. Venous thromboembolism during or after assisted reproductive technologies is predicted to emerge due to increased number of women undergoing this technique. Low molecular weight heparins was effective for preventing recurrent thromboembolism and severe obstetric complications. Women with personal or family history of thromboembolism or with history of obstetric complications should be screened for thrombophilia.

Evaluation of the plasma protein S dynamics during pregnancy using a total protein S assay: Protein S-specific activity decreased from the second trimester.

The relationship between congenital protein S (PS) deficiency and complications during pregnancy remains unclear, partly due to the difficulty of precisely evaluating the PS level with conventional assays and the physiological decrease of PS during pregnancy. A new PS assay was developed to measure the total PS antigen and activity quantitatively and calculate PS-specific activity. This study aimed to evaluate the plasma PS dynamics during pregnancy using the new PS assay and establish the reference interval for pregnant women. A total of 253 pregnant women without a personal or family history of thromboembolism were recruited. Blood samples were obtained in the first, second and third trimesters and at one month post-partum. The total PS antigen, activity, and PS-specific activity were studied. Results were analyzed by the repeated measures single-factor anovas followed by a post-hoc test using Excel Statistics. The mean ± standard deviation (IU/mL) of the total PS antigen levels in the first, second and third trimesters and 1 month post-partum were 0.67 ± 0.12, 0.67 ± 0.09, 0.68 ± 0.11 and 0.92 ± 0.13, respectively. The total PS activity (IU/mL) in the first, second and third trimesters and 1 month post-partum were 0.69 ± 0.14, 0.59 ± 0.10, 0.58 ± 0.12 and 0.87 ± 0.15, respectively. The PS-specific activity was within the normal range of nonpregnant women in the first trimester (1.02 ± 0.10) but decreased in the second and third trimesters (0.88 ± 0.09 and 0.85 ± 0.09, respectively) before increasing in the post-partum period (0.94 ± 0.08). The total PS antigen and activity decrease throughout pregnancy, while the PS-specific activity decreases in the second and third trimesters.

Thromboprophylaxis in pregnant women with thrombophilia and a history of thrombosis.

Background Despite intensive research, thromboembolism still accounts for significant maternal morbidity and mortality. We examined thrombophilia in patients with thromboembolism during pregnancy and evaluated the efficiency of antithrombotic prophylaxis in patients with thrombophilia for the prevention of recurrent thromboembolism. Materials and methods Sixty-eight women with a history of thromboembolism were managed during pregnancy, in light of their thrombotic history and the result of thrombophilia assessment. Group I (n=50) received prophylaxis with low molecular weight heparin (LMWH)±aspirin (50-100 mg/day) in preconception period or from the 1st trimester, during pregnancy and at least 6 weeks postpartum. Group II (n=18) received LMWH±aspirin from the II to III trimester. Results Thromboses were associated with pregnancy in 27 patients (39.7%), with systemic diseases - in nine (13.2%), oral contraceptives use - 22 (32.3%), immobilization due to surgery and/or trauma, long flight - six (8.9%), septic complications - two (2.9%). Nevertheless, 24.5% of patients had no apparent provoking factor for the development of thrombotic complications. Thirty-seven (54%) patients with venous thromboembolism (VTE) had familial history of VTE, and 25 (36.7%) had personal history of pregnancy complications (fetal loss syndrome, preeclampsia and placental abruption) (P<0.05 vs. control). Thrombophilia was detected in 58 (85.3%). Usual thrombogenic polymorphisms [factor V (FV) Leiden and prothrombin G20210A, heterozygous forms] were revealed in 16 (23.5%) and eight (11.7%) patients, respectively. Antiphospholipid antibodies (aPL) circulation was found in 34 (50%) patients. Non-usual thrombogenic polymorphisms were identified in 44 (64.7%) of the women and hyperhomocysteinemia - in 30 (44.2%). In group I no one had severe obstetric complications. All the patients were delivered at term and all the babies were alive. In group II moderate-to-severe obstetric complications were noted: preeclampsia - in 11 (16.2%), severe preeclampsia - seven (10.3%), preterm delivery - in 18 (26.4%) patients from subgroup II (P<0.05). Conclusions Women with a personal or a family history of thromboembolism and obstetric complications should be screened for thrombophilia. Beginning anticoagulant therapy early in such patients is effective not only for preventing recurring thrombosis but also preventing obstetric complications. Late prophylaxis after the completion of the trophoblast invasion therapy is much less effective.

Platelet activation by ADP is increased in selected patients with anterior ischemic optic neuropathy or retinal vein occlusion

To investigate whether adenosine diphosphate (ADP)-induced platelet hyperaggregability is associated with nonarteritic anterior ischemic optic neuropathy (NAION) or retinal vein occlusion (RVO).We retrospectively reviewed thrombophilia screening data of patients with NAION or RVO without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse. Patients with a positive family history for thromboembolism were not excluded. Platelet aggregation (area under the curve, AUC) after induction of 0.5, 1.0, and 2.0 µmol of ADP was estimated in 25 NAION and RVO patients and compared with 25 healthy controls.We observed significantly greater platelet aggregation post 0.5 (P = 0.002) and 1.0 (P = 0.008) µmol of ADP among NAION and RVO patients compared with healthy controls. Platelet hyperaggregability was significantly more prevalent in patients than in controls (56% vs. 8%; P = 0.0006).Our results suggest that in NAION and RVO patients without a history of arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, and cigarette abuse, platelets are significantly hyperreactive after induction of very low concentrations of ADP when compared with healthy individuals. This hyperreactivity is particularly evident in patients with a family history of thromboembolism.

Elevated lipoprotein (a) levels are an independent risk factor for retinal vein occlusion

To investigate the prevalence of lipoprotein (a) [Lp(a)] and other thrombophilic disorders among retinal vein occlusion (RVO) patients with regard to age and various risk factors. We retrospectively reviewed the medical records of 100 patients with central, hemicentral or branch RVO who had undergone routine thrombophilia screening. Data were compared with 100 controls. Both cohorts were divided into three subgroups (≤45years, >45-≤60years or >60years), depending on the patients' age at the time of the RVO or a previous thromboembolic event. Elevated Lp(a) plasma levels were significantly more prevalent among RVO patients than among controls (p<0.0001; OR: 4.8). Moreover, we determined age ≤60years by the time of the first thromboembolic event as astrong predictor of elevated Lp(a) (p=0.0002). The coincidence of elevated Lp(a) with other coagulation disorders further increased the OR for RVO to 9.3 (95% CI 2.1-41.8). Multivariate analysis revealed the presence of cardiovascular risk factors (OR: 3.1, p=0.0004), elevated lipoprotein (a) levels (OR: 5.2, p=0.0001) and increased factor VIII activity (OR: 5.9, p=0.001) as independent risk factors for the development of RVO among patients. Our results indicate that elevated plasma levels of Lp(a) are associated with the development of RVO. Selective screening of young patients and subjects with a personal or family history of thromboembolism may be helpful in identifying RVO patients with elevated Lp(a).

Selective Thrombophilia Screening in Young Patients with Retinal Artery Occlusion

Purpose: To investigate the prevalence of various thrombophilic disorders among young patients with retinal artery occlusion (RAO). Procedures: We retrospectively reviewed thrombophilia screening data of young patients ≤60 years of age with RAO and healthy controls matched for gender and age. Results: Thrombophilia screening data of 25 young patients and 62 healthy controls were analyzed. Mean patient age by the time of the RAO was 43.3 ± 10.8 years. Overall, thrombophilic defects were found to be present in 17 patients (68%) compared with 11 of 62 controls (17.7%; p < 0.0001). Multivariate logistic regression analysis confirmed a statistically significant association between the development of RAO and increased levels of lipoprotein(a) (odds ratio: 9.48; p = 0.001) and factor VIII (odds ratio: 6.41; p = 0.024). There was a strong association between the presence of thrombophilic disorders and a personal or family history of thromboembolism (p = 0.01). Conclusions: Our results indicate that screening for thrombophilic disorders among selected young patients with RAO yields positive results in a high percentage of cases.

End-stage renal disease and thrombophilia.

Chronic kidney disease is an established risk factor for arterial and venous thromboembolism (TE). Whereas the overall risk of TE in moderately decreased kidney function is approximately 2.5-fold higher compared to patients with normal renal function, the risk increase is 5.5-fold in patients with severe renal dysfunction. In patients with renal dysfunction and arterial thrombosis (OR: 4.9), malignancy (OR: 5.8) surgery (OR: 14.0) or thrombophilia (OR: 4.3) the risk to suffer from venous TE is higher compared to the risk associated to the baseline renal dysfunction alone. The treatment options for end-stage renal diseases include hemodialysis, peritoneal dialysis and kidney transplantation. During all treatment modalities thrombotic complications have been described, namely catheter malfunction and shunt thrombosis in patients undergoing hemodialysis in up to 25% of patients, and TE, pulmonary embolism or graft vessel thrombosis in approximately 8% of patients. The reported incidence of reno-vascular thrombosis following renal transplantation leading to hemorrhagic infarction with organ rejection or organ loss varied between 2-12%. Keeping in mind the multifactorial etiology of TE in patients with kidney dysfunction a general screening for thrombophilia in this patient group is not indicated. Selected screening on an individual patient basis should be discussed if the family history for TE is positive or the patient itself had suffered one thrombosis before the onset of the renal disease or multiple TEs during hemodialysis or post kidney transplantation in patients waiting for living donor kidney transplantation.

Molecular basis and thrombotic manifestations of antithrombin deficiency in 15 unrelated Chinese patients

Antithrombin (AT) deficiency is associated with an increasing risk of thrombosis. 15 unrelated patients with AT deficiency defined by thrombophilic assays were recruited and detailed clinical information about patients, focusing on the personal and family history of thromboembolism (TE), were recorded. Mutation analysis was performed by direct sequencing of an AT gene (SERPINC1) in the patients and their family members. A total of 15 heterozygous causative mutations, each being identified in one family, were identified. Five mutations (33.3%) were reported here for the first time, including three null mutations (Ser36X, Lys70X and Try307X) and two missense mutations (Phe123Cys and Leu340Phe) probably impairing the structural integrity and stability of protein based on the AT structural analysis. Of the 15 patients, 33.3% (5/15) had additional risk factors and only one patient presented with additional genetic alteration causing an early onset of thrombosis. Fourteen patients (93.9%) suffered from multisite recurrent thrombotic episodes after a first episode of thrombosis. 93.3% of the patients experienced deep vein thrombosis (DVT) and 40.0% presented with mesenteric venous thrombosis (MVT). In addition, both venous and arterial thrombosis was present in two unrelated patients. 51.0% subjects with AT deficiency in the 15 unrelated pedigrees experienced TE events. Prophylactic anticoagulation may be suggested in AT-deficient patients to avoid the recurrent and multisite thrombosis. The association of primary MVT and AT deficiency is highlighted.

Postpartum deep vein thrombosis and pulmonary embolism in twin pregnancy: undertaking of clinical symptoms leading to massive complications

BackgroundDeep Vein Thrombosis (DVT) is an important cause of morbidity and is the first cause of maternal death after delivery in Western Nations. The risk of venous thromboembolism is present throughout the pregnancy and is maximal during postpartum, especially after twin delivery. Many of the signs and symptoms of DVT overlap those of a normal pregnancy causing difficulty for diagnosis.Case reportWe report the case of a 33 year-old woman transferred to our Department one week after caesarean section for twin delivery. She presented with severe abdominal pain, fever, abdominal distension and shortness of breath. She had no personal or family history of thromboembolism. Computerized Tomography Scan revealed right ovarian vein thrombosis, left renal vein thrombosis extending up to the Inferior Vena Cava and pulmonary embolism with bilateral pleural effusion. Caval filter was positioned and anticoagulation therapy associated with antibiotics was instituted. Pancreatitis showed up two days after and was promptly treated. Three months after discharge the caval filter was removed and oral anticoagulation was stopped. During a 12-months follow-up, she remained stable and symptom free.ResultsOvarian vein thrombosis is rare but recognition of signs and symptoms is fundamental to start adequate therapy and avoid potential serious sequelae. The risk for maternal postpartum ovarian vein thrombosis is increased by caesarean section delivery of twins. Such patients should be closely monitored. We illustrated how an underestimated condition can lead to massive complications.

High Prevalence of Thrombophilic Traits in Children with Family History of Thromboembolism

High Prevalence of Thrombophilic Traits in Children with Family History of Thromboembolism

Coagulation disorders and the risk of retinal vein occlusion

Over the past years, there has been a dramatic increase in the number of identifiable causes of thrombophilia. However, to date, there are no large, prospective studies to assess an optimal, cost-effective approach with regard to screening and case finding for thrombophilic risk factors in patients presenting with retinal vessel occlusion. Two hundred twenty-eight patients with retinal vein occlusion (RVO) and 130 age-matched healthy controls were prospectively screened for thrombophilic risk factors. Both cohorts were divided into three subgroups, depending on the patients' age at the time of the RVO or a previous thromboembolic event. Patient age < or =45 years was associated with a high prevalence of coagulation disorders (p<0.0001). Among patients < or =45 years and >45 to < or =60 years, a family history of thromboembolism was strongly associated with the presence of thrombophilic disorders. The absence of cardiovascular risk factors was found to be a strong predictor for the presence of coagulation disorders in all patient groups (< or =45 years, p=0.003; >45 to < or =60 years, p=0.0008; >60 years, p=0.001). Multivariate analysis revealed the presence of resistance to activated protein C (p=0.014), antiphospholipid antibodies (p=0.022), and deficiency of the anticoagulant proteins (p=0.05) as independent risk factors for the development of RVO among patients < or =45 years. Our results indicate that thrombophilic disorders are associated with the development of retinal vein occlusion in patients < or =45 years by the time of the RVO or a previous thromboembolic event, in patients with a family history of thromboembolism, or in patients without cardiovascular risk factors.

Prothrombin Gene G20210A Mutation and Obstetric Complications

To estimate whether maternal carriage of the prothrombin gene G20210A mutation is associated with pregnancy loss, preeclampsia, placental abruption, or small for gestational age (SGA) neonates in a low-risk, prospective cohort. This was a secondary analysis of the Eunice Kennedy Shriver National Institute of Child Health and Human Development factor V Leiden study, a multicenter, prospective, observational cohort of 5,188 unselected singleton gestations. A total of 4,167 first-trimester samples were available for analysis and were tested for the prothrombin G20210A mutation. Obstetric complications were compared between women with and without the prothrombin G20210A mutation by univariable and multivariable analysis. A total of 157 (3.8%) women had the prothrombin gene mutation (156 heterozygous and one homozygous). Carriers of the prothrombin G20210A mutation had similar rates of pregnancy loss, preeclampsia, SGA neonates, and abruption compared with noncarriers. Results were similar in a multivariable analysis controlling for age, race, prior pregnancy loss, prior SGA neonates, and family history of thromboembolism. Three thromboembolic events occurred in women testing negative for the mutation. There was no association between the prothrombin G20210A mutation and pregnancy loss, preeclampsia, abruption, or SGA neonates in a low-risk, prospective cohort. These data raise questions about the practice of screening women without a history of thrombosis or adverse pregnancy outcomes for this mutation. II.

Pulmonary embolism following thrombosis of the brachial vein after shoulder arthroscopy. A case report

Thromboembolic complications are very rare after arthroscopic surgery of the shoulder. We report the case of a 25-year-old who presented thrombophlebitis of the brachial vein complicated by pulmonary embolism following arthroscopic surgery for posterior instability of the shoulder. No hemostasis impairment was found in this patient. The factors arguing in favor of thrombosis that had been retained from the literature were the lateral decubitus position with traction of the limb in its axis, prolonged surgical time, use of interscalene brachial plexus block, and a general condition susceptible to thrombosis (personal or family history of thromboembolism, genetic risk factor for thrombosis, smoking, obesity, neoplasia). There are currently no guidelines on the need for thromboembolism prevention during shoulder arthroscopy.

Selektives Thrombophiliescreening junger Patienten mit venösen retinalen Gefäßverschlüssen

The potential impact of coagulation abnormalities on retinal vascular occlusive diseases, individually and in combination with cardiovascular risk factors, remains unclear. In a prospective case-control study a cohort of 74 young patients with central, hemicentral or branch retinal vein occlusion (RVO) (<or= 45 years at the time of the RVO or a previous thromboembolic event) and 74 subjects matched for age and sex were prospectively screened for thrombophilic risk factors. Overall, thrombophilic defects were found to be present in 38 of the 74 patients (51.4 %) and in 8 of 74 (10.8 %) controls (p < 0.0001). We found a strong association between the presence of thrombophilic disorders and a family history of thromboembolism (p < 0.0001). Patients without cardiovascular risk factors had a statistically significant higher frequency of coagulation disorders than patients with these risk factors (p = 0.0025). Our results indicate that thrombophilic disorders are associated with the development of retinal vein occlusion. Selective screening of young patients, patients with a personal or family history of thromboembolism, and patients without cardiovascular risk factors may be helpful in identifying retinal vein occlusion patients with thrombophilic defects.

Selective thrombophilia screening of patients with nonarteritic anterior ischemic optic neuropathy

To date, the question whether there is a relationship between thrombophilic disorders and the development of nonarteritic ischemic optic neuropathy (NAION) remains controversial. We sought to investigate the prevalence of various coagulation defects among NAION patients <65 years of age, and to provide clinical guidelines for a selective thrombophilia screening. A cohort of 35 patients <65 years of age with NAION and 70 controls matched for age and sex were prospectively screened for thrombophilic risk factors. Overall, thrombophilic defects were found to be present in 18 of 35 patients (51.4%) and in 12 of 70 (17.1%) controls (P = 0.0005). The most frequent coagulation disorders were increased levels of factor VIII (P = 0.015) and lipoprotein (a) (P = 0.005). Patients without cardiovascular risk factors had a statistically significant higher frequency of coagulation disorders than patients with these risk factors (P = 0.0059). There was a strong association of coagulation disorders and a personal or family history of thromboembolism (P = 0.028). Moreover, we determined the age of <or=55 years at the time of the first thromboembolic event or NAION as a strong predictor of underlying thrombophilia (P = 0.0002). Our results indicate that thrombophilic disorders are associated with the development of NAION in specific subgroups of patients. Selective screening of young patients, subjects with a personal or family history of thromboembolism, and patients without cardiovascular risk factors may be helpful in identifying NAION patients with thrombophilic defects.

Risk and Risk Estimation of Placental Abruption

Placental abruption remains a major cause of fetal and maternal morbidity, including stillbirths. Reported perinatal mortality rates vary widely, from 2% to 67%. There are several established risk factors such as smoking, hypertension, trauma, and thrombophilia. Thrombophilia is also associated with repeated first-trimester loss and second- or third-trimester loss, but whether a history of such losses also increases the risk of abruption has not been established. This retrospective case–control study sought risk factors for placental abruption in 161 affected women and 2371 control women. The diagnosis usually was made clinically based on profuse vaginal bleeding starting in the third trimester, painful contractions, and clinical examination of the placenta. Trimesters were defined by gestational ages of 13 and 26 weeks. Women with placental abruption had significantly higher prevalence rates of smoking, intrauterine growth retardation, preeclampsia, low Apgar scores, and cesarean deliveries. Affected women had lower first-trimester hemoglobin values than control women, and twice as many affected women had a final hemoglobin less than 11.0 mg/dL. Previous second-trimester and repeated fetal loss correlated significantly with an increased risk of placental abruption. In women with preeclampsia, the risk was increased 3-fold. Although none of the affected women had a history of venous thromboembolism, compared with 0.4% of control women, they were significantly more likely to have a family history of thromboembolism (19.6% vs 6.7%). Risk scores were derived from the data. The risk of placental abruption increased from 2.5-fold for those with a score of one to nearly 100-fold in those having a score of 4 or above. The corresponding odds ratios for placental abruption were 2.7 and 94.5. Second- and third-trimester fetal losses and repeated losses were significant risk factors for placental abruption in this retrospective study. The risk score may prove helpful in deciding on appropriate monitoring in women with third-trimester bleeding or premature contractions.

DIAGNOSTIC VALUE OF FAMILY HISTORIES OF THROMBOSIS TO IDENTIFY CHILDREN WITH THROMBOPHILIA

Thrombophilia screening is a time-consuming and expensive procedure. Information about thromboembolism among relatives may be a simple method to identify those at risk of having thrombophilia. In a cross-sectional clinical study the authors have investigated the role of such family histories to detect children with thrombophilia. In 202 children a family history of venous or arterial thromboembolism was recorded. The participants were either children with congenital heart defects at the time of a scheduled cardiac catheterization (n = 134) or children with newly diagnosed cancer (n = 68). Questions were answered, on the spot, by the parents, at the same time as blood samples for thrombophilia screening were taken. Questions about family history of thromboembolism were completed in 184 children, of whom 114 children (62%) were positive, and 35 of these had relatives with venous thromboembolic events. Only one child had an affected first-degree relative. Thrombophilic alterations were observed in 60 children (30%), and 25 of these were defined as inherited. A positive family history of venous origin increased the relative risk of a child having inherited thrombophilia to 2.35 (95% confidence interval 1.1–5.2). Information about familial arterial thromboembolism was not useful in spotting children with prothrombotic risk factors. These results indicate that questioning about family history of venous thromboembolism may identify children with genetic thrombophilia, but the association is not strong. The authors encourage similar larger-scale studies to enlighten the issue fully.

Thromboembolism.

Venous thomboembolism (VTE) causes only about 2% of maternal deaths in the developing world but is a leading cause of direct maternal deaths in developed countries. Pregnancy increases the risk of VTE through venous stasis, changes in blood coagulability and damage to vessels. Early diagnosis of VTE depends crucially on awareness of the condition but clinical diagnosis is unreliable in pregnancy and objective testing is essential. Compression or duplex ultrasonography is used to diagnose deep venous thrombosis and a ventilation/perfusion scan for pulmonary embolism. Low molecular weight heparins are safe and effective for treatment and for thromboprophylaxis in pregnancy. All women should undergo risk assessment in early pregnancy or preferably before pregnancy. Identifying risk factors such as obesity, or a past or family history of thromboembolism, allows at-risk women to be offered thromboprophylaxis. Guidelines on thromboprophylaxis have reduced deaths after caesarean section and are now being developed for all women.