Thrombocalc: implementation and uptake of personalized postpartum venous thromboembolism risk assessment in a high-throughput obstetric environment

Thrombotic complications in pregnancy: a case-based review of the evidence

Pregnancy is a prothrombotic state due to an estrogen-driven shift in the coagulation system, increased venous stasis, and external restriction of blood flow caused by the gravid uterus. Venous thromboembolism (VTE) is a leading cause of morbidity and mortality in pregnancy. Preventing, recognizing, and treating thrombosis in pregnancy, as well as the postpartum period, often challenges decision making in the clinical setting. In early pregnancy, guidance with respects to thrombophilia testing and anticoagulation in increasing the likelihood of live birth among patients with recurrent miscarriages is evolving. This review explores emerging data that support clinical decision making in thrombosis care in women with common thrombotic complications in pregnancy. The first case outlines VTE diagnosis in pregnancy, initial anticoagulation management, management around delivery and postpartum, and subsequent long-term anticoagulation treatment. The second case examines testing for inherited and acquired thrombophilia in the setting of recurrent miscarriage and the management of obstetric antiphospholipid syndrome. Lastly, the third case reviews VTE risk assessment and prevention in pregnancy and the postpartum period, as well as duration and dose of postpartum thromboprophylaxis. Review of these common clinical scenarios surrounding thrombotic complications in pregnancy demonstrates recent advances in high-quality data, current gaps in knowledge, and variation in expert opinion. Ultimately, multidisciplinary discussion and teamwork remain key to optimal, safe care. Clinicians must prioritize collaborative, high-quality trials and prospective clinical management studies to better understand and define best practice in this population.

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

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

Pathophysiology of the Venous Thromboembolism Risk in Preeclampsia

Preeclampsia complicates up to 8% of pregnancies and is a leading cause of fetomaternal morbidity andmortality. Treatment options are limited, with supportive care and delivery of the placenta representing the cornerstone of current management strategies. Derangements in blood coagulation are wellrecognised in this disorder and appear to favour an increased risk of venous thromboembolism among affected women. This risk appears to be most significant in the postpartum period. The mechanisms underlying this increased thrombosis risk remain to be fully elucidated although increased expression of procoagulant factors, endothelial dysfunction, attenuation of endogenous anticoagulant activity and increased platelet activity have been implicated in the prothrombotic tendency. Preeclampsia is also occasionally complicated by life-threatening haemorrhagic events and current evidence suggests that in some severe manifestations of this disease a coagulopathy with a clinical bleeding tendency may be the predominant haemostatic abnormality. Identifying affected women at significant risk of thrombosis and managing the competing thrombotic and haemorrhagic risks continue to be a significant clinical challenge. Derangements in blood coagulation are also implicated in the pathogenesis of preeclampsia; however, the role of antiplatelet or anticoagulant drugs in the prevention and treatment of this disorder remains a source of considerable debate. In addition, the potential role of specific haemostatic markers as diagnostic or screening tools for preeclampsia has also yet to be determined. Further characterisation of the underlying molecular mechanisms would likely be of major translational relevance and could provide insights into the pathogenesis of this disease as well as the associated haemostatic dysfunction.

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.

Prevalence of postpartum venous thromboembolism risk factors in an Irish urban obstetric population

BACKGROUND

Obstetric venous thromboembolism (VTE) is a leading cause of maternal morbidity and mortality. A clear understanding of the burden of VTE risk at a population level is a prerequisite to effective prevention; however, existing data are limited.

OBJECTIVES

Describe the prevalence and patterns of VTE risk factors among postpartum women and consider the implications for VTE prevention practices.

METHOD

We undertook a cross-sectional study of prospectively collected data from sequential postpartum VTE risk assessments completed between January 2015 and December 2017 in the Rotunda Hospital, Dublin.

RESULTS

We analyzed postpartum VTE risk factors in a large unselected Irish urban obstetric cohort of 21 019 consecutively sampled women. This represents more than 90% of all women giving birth in a single institution over a 3-year period. The most common VTE risk factors related to maternal characteristics and delivery characteristics, including overweight and obesity (36%), age ≥35 (35%) and cesarean delivery (32%). More than three-quarters of women had at least 1 VTE risk factor (78%) and more than 40% had multiple (2 or more) VTE risk factors. One-fifth of women had no VTE risk factors before delivery, yet went on to develop VTE risk factors during delivery or in the postpartum period. Reflecting the differences in thromboprophylaxis thresholds internationally, the proportion of women who would have received a recommendation for postpartum thromboprophylaxis ranged from 7% to 37% under various clinical guidelines.

CONCLUSION

This study demonstrates the high prevalence of VTE risk factors among postpartum women. Postpartum VTE risk is highly individualized and complex.

Venous thromboembolism incidence in the Ireland east hospital group: a retrospective 22-month observational study

OBJECTIVES

To determine the incidence of venous thromboembolism (VTE) and the incidence of hospital-acquired VTE (HA-VTE) arising within the population served by the Ireland East Hospital Group (IEHG).

DESIGN

/home/user/Documents/Sathish Kumar G/RFO/June/21-06-2019/bmjopen_iss_9_7_20190621_1/ A retrospective observational study was conducted using hospital discharge data obtained from the hospital inpatient enquiry data reporting system. In this system, VTE events recorded as 'primary diagnosis' represented the reason for initial hospital admission, whereas VTE recorded as a 'secondary diagnosis' occurred following admission and were therefore used as an approximation of HA-VTE. These data were used to estimate the overall incidence of VTE and the proportion of these events which were hospital-acquired.

SETTING

The IEHG is the largest hospital group in the Irish healthcare system and serves a population of over 1 million individuals.

PARTICIPANTS

Data were generated from records pertaining to the 2727 patient admission episodes where a diagnosis of VTE was made during the 22-month study period.

RESULTS

During the study period, 2727 VTE events were recorded within the IEHG (which serves a population of 1 036 279) corresponding to an incidence of 1.44 (95% CI 1.36 to 1.51) per 1000 per annum. 1273 (47%) of VTE events were recorded as secondary VTE. The incidence of VTE was highest among individuals over 85 years of age (16.03 per 1000;95% CI 12.81 to 19.26) and was more common following emergency hospital admission.

CONCLUSION

These data suggest that HA-VTE accounts for at least 47% of all VTE events arising within a hospital group serving a population of over 1 million individuals within the Ireland. Given that HA-VTE is a well-recognised source of (potentially preventable) hospital deaths, these findings provide a compelling argument for prioritising strategies directed at reducing the risk of VTE among hospital patients served by the IEHG and within the Ireland as a whole.

United Kingdom recommendations for obstetric venous thromboembolism prophylaxis: Evidence and rationale

Venous thromboembolism (VTE) is a leading cause of maternal death in the United Kingdom. To address this problem guidance from the Royal College of Obstetricians and Gynaecologists (RCOG) has been developed that recommends the assessment of a woman's risk of thrombosis at specific time-points during pregnancy and postnatally at the time of delivery. The RCOG guidelines provide clinicians with a framework to inform decision-making on the use of thromboprophylaxis and are based on the premise that the higher risk a woman has for VTE, the more likely she is to benefit from prophylaxis - determining her level of risk is based on the number and characteristics of the risk factors that she has. This article will address the pathophysiology of VTE in pregnancy, evidence behind the risk factors for VTE and the use of thromboprophylactic agents. Further, it will reflect on the rationale behind the RCOG guidance.