Elevated venous thromboembolism risk in preeclampsia: molecular mechanisms and clinical impact

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

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

Evaluating Thromboprophylaxis Strategies for High-Risk Pregnancy: A Current Perspective

Venous thromboembolism (VTE) represents one of the leading causes of death during pregnancy. The greatest risk for it is the presence of medical or family history of VTE, stillbirth, cesarean section and selected thrombophilia. Appropriate thromboprophylaxis has the potential to decrease the risk of VTE in at-risk pregnant patients by 60-70%. Based on this, the authors reviewed the PubMed, Web of Science and Scopus databases to identify the possibilities of thromboprophylaxis in pregnant patients with a high risk of VTE. Moreover, they summarized its management in specific situations, such as cesarean delivery or neuraxial blockade. Currently, low-molecular-weight heparins (LMWH) are the preferred drugs for anticoagulant thromboprophylaxis in the course of pregnancy and postpartum due to easy administration and a lower rate of adverse events.

Extensive Postpartum Upper and Lower Extremity Deep Vein Thrombosis in a Patient With a History of Preeclampsia

We describe the case of a 19-year-old woman with no significant medical history who developed progressive right-sided neck pain and palpitations one month following a pregnancy complicated by preeclampsia. Family history was significant for unprovoked deep vein thrombosis (DVT) and pulmonary embolism (PE) in her father at age 44. Systemic examination revealed mild swelling of the right upper extremity with pain on palpation. Computed tomography (CT) of the thorax with contrast demonstrated extensive occlusion of right upper extremity veins and collateralization of chest wall veins. Pulmonary emboli were present bilaterally in the segmental and subsegmental branches of the lower lobe pulmonary arteries. CT of the abdomen with contrast revealed thrombi in the left common and external iliac veins. Thrombophilia screening was normal. The patient was treated with enoxaparin and ampicillin/sulbactam. Her clinical condition improved, and she was discharged with an outpatient clinic follow-up appointment.

Pregnancy complications and later life women's health

There has been increasing recognition of the association between various pregnancy complications and development of chronic disease in later life. Pregnancy has come to be regarded as a physiological stress test, as the strain it places on a woman's body may reveal underlying predispositions to disease that would otherwise remain hidden for many years. Despite the increasing body of data, there is a lack of awareness among healthcare providers surrounding these risks. We performed a narrative literature review and have summarized the associations between the common pregnancy complications including gestational hypertension, pre-eclampsia, gestational diabetes, placental abruption, spontaneous preterm birth, stillbirth and miscarriage and subsequent development of chronic disease. Hypertensive disorders of pregnancy, spontaneous preterm birth, gestational diabetes, pregnancy loss and placental abruption are all associated with increased risk of various forms of cardiovascular disease. Gestational diabetes, pre-eclampsia, early miscarriage and recurrent miscarriage are associated with increased risk of diabetes mellitus. Pre-eclampsia, stillbirth and recurrent miscarriage are associated with increased risk of venous thromboembolism. Pre-eclampsia, gestational diabetes and stillbirth are associated with increased risk of chronic kidney disease. Gestational diabetes is associated with postnatal depression, and also with increased risk of thyroid and stomach cancers. Stillbirth, miscarriage and recurrent miscarriage are associated with increased risk of mental health disorders including depression, anxiety and post-traumatic stress disorders. Counseling in the postnatal period following a complicated pregnancy, and advice regarding risk reduction should be available for all women. Further studies are required to establish optimal screening intervals for cardiovascular disease and diabetes following complicated pregnancy.

Preeclampsia: Platelet procoagulant membrane dynamics and critical biomarkers

A state-of-the-art lecture titled "Preeclampsia and Platelet Procoagulant Membrane Dynamics" was presented at the International Society on Thrombosis and Haemostasis (ISTH) Congress in 2022. Platelet activation is involved in the pathophysiology of preeclampsia and contributes to the prothrombotic state of the disorder. Still, it remains unclear what mechanisms initiate and sustain platelet activation in preeclampsia and how platelets drive the thrombo-hemorrhagic abnormalities in preeclampsia. Here, we highlight our findings that platelets in preeclampsia are preactivated possibly by plasma procoagulant agonist(s) and overexpress facilitative glucose transporter-3 (GLUT3) in addition to GLUT1. Preeclampsia platelets are also partially degranulated, procoagulant, and proaggregatory and can circulate as microaggregates/microthrombi. However, in response to exposed subendothelial collagen, such as in injured vessels during cesarean sections, preeclampsia platelets are unable to mount a full procoagulant response, contributing to blood loss perioperatively. The overexpression of GLUT3 or GLUT1 may be monitored alone or in combination (GLUT1/GLUT3 ratio) as a biomarker for preeclampsia onset, phenotype, and progression. Studies to further understand the mediators of the platelet activation and procoagulant membrane dynamics in preeclampsia can reveal novel drug targets and suitable alternatives to aspirin for the management of prothrombotic tendencies in preeclampsia. Finally, we summarize relevant new data on this topic presented during the 2022 ISTH Congress.

Vital NETosis vs. suicidal NETosis during normal pregnancy and preeclampsia

Background: NETosis occurs in the context of infection or inflammation and results in the expulsion of decondensed DNA filaments called NETs (Neutrophil Extracellular Traps) into the extracellular environment. NETosis activates coagulation and contributes to the thrombotic risk of inflammatory diseases. To date, two mechanisms of NETosis have been identified: suicidal NETosis, in which neutrophils die after expelling the filaments; and vital NETosis, in which expulsion appears without altering the membrane. Human pregnancy is associated with a mild pro-inflammatory state, which is increased in the event of complications such as preeclampsia (PE). NETosis has been observed in these situations, but the mechanism of its production has not yet been studied. The aim of our study was to evaluate the balance of vital vs. suicidal NETosis in normal pregnancy and in PE. Patients/Methods: Neutrophils from healthy volunteers were stimulated with plasma from normal pregnancies (n = 13) and from women developing preeclampsia (n = 13). Immunofluorescent labelling was performed to determine the percentages and origin of NETs in both groups. Inhibition with suicidal or vital NETosis inhibitors was also performed to validate our results. Results: We found a significant increase in NETs in women with PE compared to women with normal pregnancies. We showed that vital and non-vital NETosis are present in normal and preeclamptic pregnancies. We demonstrated that the higher proportion of NETs observed in PE was due to non-vital NETosis whose main component is represented by suicidal NETosis. Discussion: These results suggest the important part of non-vital NETosis in the pathophysiology of PE.

Preeclampsia and Venous Thromboembolism: Pathophysiology and Potential Therapy

Preeclampsia (PET) is a multisystem inflammatory disorder that represents a leading cause of feto-maternal morbidity and mortality, complicating 2–5% of all pregnancies. PET incurs an increased risk of venous thromboembolism, which is one of the leading causes of death in pregnancy and in the postpartum period. This prothrombotic phenotype is attributable to the maternal phase of PET, which is characterized by a systemic inflammatory response and coagulation activation. Research continues to be undertaken in terms of preventative measures, however, currently revolves around pharmacological low dose aspirin initiated in the first trimester of pregnancy for those with risk factors. Treatment involves antenatal corticosteroids for fetal lung development in preterm birth, parenteral magnesium sulfate for fetal neuroprotection and maternal seizure prophylaxis, and timely birth of the fetus and placenta being the only definitive treatment of PET. Patients with a venous thromboembolism (VTE) risk deemed to be >1–3% are treated with pharmacological thromboprophylaxis in the form of low molecular weight heparin. Completing each woman’s VTE risk assessment is crucial, particularly in the setting of PET, as there is also a proven associated competing hemorrhagic risk.

Viscoelastic haemostatic point-of-care assays in the management of postpartum haemorrhage: a narrative review

Viscoelastic haemostatic assays provide rapid testing at the bed-side that identify all phases of haemostasis, from initial fibrin formation to clot lysis. In obstetric patients, altered haemostasis is common as pregnancy is associated with coagulation changes that may contribute to bleeding events such as postpartum haemorrhage, as well as thrombosis events. In this narrative review, we examine the potential clinical utility of viscoelastic haemostatic assays in postpartum haemorrhage and consider the current recommendations for their use in obstetric patients. We discuss the clinical benefits associated with the use of viscoelastic haemostatic assays due to the provision of (near) real-time readouts with a short turnaround, coupled with the identification of coagulation defects such as hypofibrinogenaemia. The use of viscoelastic haemostatic assay-guided algorithms may be beneficial to diagnose coagulopathy, predict postpartum haemorrhage, reduce transfusion requirements and monitor fibrinolysis in women with obstetric haemorrhage. Further studies are required to assess whether viscoelastic haemostatic assay-guided treatment improves clinical outcomes, and to confirm the utility of prepartum viscoelastic haemostatic assay measurements for identifying patients at risk of postpartum haemorrhage.

Circulatory Neutrophils Exhibit Enhanced Neutrophil Extracellular Trap Formation in Early Puerperium: NETs at the Nexus of Thrombosis and Immunity

Pregnancy is associated with elevated maternal levels of cell-free DNA of neutrophil extracellular trap (NET) origin, as circulatory neutrophils exhibit increased spontaneous NET formation, mainly driven by G-CSF and finely modulated by sex hormones. The postpartum period, on the other hand, involves physiological alterations consistent with the need for protection against infections and fatal haemorrhage. Our findings indicate that all relevant serum markers of neutrophil degranulation and NET release are substantially augmented postpartum. Neutrophil pro-NETotic activity in vitro is also upregulated particularly in post-delivery neutrophils. Moreover, maternal puerperal neutrophils exhibit a strong pro-NETotic phenotype, associated with increased levels of all key players in the generation of NETs, namely citH3, MPO, NE, and ROS, compared to non-pregnant and pregnant controls. Intriguingly, post-delivery NET formation is independent of G-CSF in contrast to late gestation and complemented by the presence of TF on the NETs, alterations in the platelet activity status, and activation of the coagulation cascade, triggered by circulating microparticles. Taken together, our results reveal the highly pro-NETotic and potentially procoagulant nature of postpartum neutrophils, bridging an overt immune activation with possible harmful thrombotic incidence.

Platelet-derived extracellular vesicles may contribute to the hypercoagulable state in preeclampsia

It has previously been shown that preeclampsia is associated with disturbed hemostasis and that extracellular vesicles (EVs) play important role in the regulation of hemostatic homeostasis. Thus, we hypothesized that the altered procoagulant characteristics of circulating platelet-derived EVs may contribute to the disturbed hemostasis in preeclampsia. Using multicolor flow cytometry, we have analyzed both tissue factor expressing procoagulant EVs and platelet-derived EV subpopulations derived from resting and activated thrombocytes by examining them in plasma samples of preeclamptic patients and pregnancy-matched healthy individuals. Compared to pregnancy-matched healthy individuals in preeclamptic patients a significantly (p < 0.05) higher ratio of Annexin-V positive activated platelets and a higher number of CD142⁺ tissue factor bearing procoagulant EVs were found, whereas the absolute amount of circulating CD41a⁺ platelet-derived EVs and CD62P⁺/CD41a⁺ EVs produced by activated thrombocytes was significantly lower in the plasma of preeclamptic women. In the plasma samples, there was no significant difference in the amount of CD63⁺ platelet-derived EVs. We propose that increased platelet activation and tissue factor expression of platelet derived extracellular vesicles may contribute to the hypercoagulable state observed in preeclampsia.

Prothrombotic state associated with preeclampsia

PURPOSE OF REVIEW

Preeclampsia is a common complication of pregnancy and contributes significantly to maternal and fetal morbidity and mortality. A protective hypercoagulable state is often developed during late pregnancy and can evolve into a prothrombotic state in patients with preeclampsia. The underlying mechanism of this prothrombotic transition remains poorly understood. We discuss recent progress in understanding the pathophysiology of preeclampsia and associated prothrombotic state.

RECENT FINDINGS

The hypercoagulable state developed during pregnancy is initiated by placental factors and progresses into the prothrombotic state in preeclampsia when the placenta is subjected ischemic and oxidative injuries. The cause of the preeclampsia-induced prothrombotic state is multifactorial, involving not only placental factors but also maternal conditions, which include genetic predisposition, preexisting medical conditions, and conditions acquired during pregnancy. Endotheliopathy is the primary pathology of preeclampsia and contributes to the prothrombotic state by inducing the dysregulation of coagulation, platelets, and adhesive ligands.

SUMMARY

Patients with preeclampsia often develop a severe prothrombotic state that predisposes them to life-threatening thrombosis and thromboembolism during and after pregnancy. Early recognition and treatment of this prothrombotic state can improve maternal and infant outcomes of preeclampsia patients.

Risk of pre-eclampsia in patients with a maternal genetic predisposition to common medical conditions: a case-control study

OBJECTIVE

To assess whether women with a genetic predisposition to medical conditions known to increase pre-eclampsia risk have an increased risk of pre-eclampsia in pregnancy.

DESIGN

Case-control study.

SETTING AND POPULATION

Pre-eclampsia cases (n = 498) and controls (n = 1864) in women of European ancestry from five US sites genotyped on a cardiovascular gene-centric array.

METHODS

Significant single-nucleotide polymorphisms (SNPs) from 21 traits in seven disease categories (cardiovascular, inflammatory/autoimmune, insulin resistance, liver, obesity, renal and thrombophilia) with published genome-wide association studies (GWAS) were used to create a genetic instrument for each trait. Multivariable logistic regression was used to test the association of each continuous scaled genetic instrument with pre-eclampsia. Odds of pre-eclampsia were compared across quartiles of the genetic instrument and evaluated for significance.

MAIN OUTCOME MEASURES

Genetic predisposition to medical conditions and relationship with pre-eclampsia.

RESULTS

An increasing burden of risk alleles for elevated diastolic blood pressure (DBP) and increased body mass index (BMI) were associated with an increased risk of pre-eclampsia (DBP, overall OR 1.11, 95% CI 1.01-1.21, P = 0.025; BMI, OR 1.10, 95% CI 1.00-1.20, P = 0.042), whereas alleles associated with elevated alkaline phosphatase (ALP) were protective (OR 0.89, 95% CI 0.82-0.97, P = 0.008), driven primarily by pleiotropic effects of variants in the FADS gene region. The effect of DBP genetic loci was even greater in early-onset pre-eclampsia cases (at <34 weeks of gestation, OR 1.30, 95% CI 1.08-1.56, P = 0.005). For other traits, there was no evidence of an association.

CONCLUSIONS

These results suggest that the underlying genetic architecture of pre-eclampsia may be shared with other disorders, specifically hypertension and obesity.

TWEETABLE ABSTRACT

A genetic predisposition to increased diastolic blood pressure and obesity increases the risk of pre-eclampsia.

Oxidative status of maternal blood in pregnancies burdened by inherited thrombophilias

Oxidative status of maternal blood represents an important parameter of pregnancy that is involved in both, regulation of physiological processes and (if significantly altered) development of different pregnancy complications. Inherited thrombophilias represent genetic disorders that increase the risk of thromboembolism in pregnancy. Little is known about the impact of thrombophilia on the oxidative status of maternal blood. In this study, we analyzed oxidative status of blood of 56 women with pregnancies burdened by inherited thrombophilias. The status was established at three different trimesters using biochemical assays and electrochemical measurements, and it was compared to 10 age- and trimester-matching controls. Activities of superoxide dismutase, catalase, and glutathione reductase in the 1st and the 2nd trimester of thrombophilic pregnancy were lower than controls. Also, there was less oxidation in the plasma, according to higher concentration of reduced thiols and lower oxidation-reduction potential. Therefore, it appears that thrombophilic mothers do not experience oxidative stress in the circulation in the first two trimesters. However, the rise in GPx, GR and SOD activities in the 3rd trimester of thrombophilic pregnancy implies that the risk of oxidative stress is increased during the late pregnancy. These results are important for developing antioxidative treatment that could tackle thrombophilia-related pregnancy complications.

Immediate postpartum management of patients with severe hypertensive disorders of pregnancy: pathophysiology guiding practice

Developing clinically-focused evidence and experience-based approaches to improve maternity care is a national priority. Safety and quality collaborative initiatives related to management of hypertensive disorders of pregnancy are vital in the implementation of improved care. We reviewed the obstetric literature to construct a concise summary of the core pathophysiologic issues, practice principles and clinical interventions which are foundational for physicians providing immediate postpartum care for patients with severe pregnancy-related hypertension (including those with eclampsia, HELLP syndrome, and superimposed preeclampsia inclusive of those with gestational hypertension that develop severe range blood pressures). While based largely upon the American College of Obstetrics and Gynecology (ACOG) Hypertension Task Force Guidelines released in 2013 as well as updated 2018 guidelines set forth by ACOG for hypertensive disorders of pregnancy, this summary goes beyond the basic safety bundles for hypertension management and lays a pathophysiologic foundation for the immediate postpartum care of patients with severe hypertensive disorders of pregnancy.

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.

Hypertensive Complications of Pregnancy and Risk of Venous Thromboembolism

Hypertension during pregnancy and preeclampsia are associated with increased arterial thrombotic risk in later life. Whether these complications are associated with risk of venous thromboembolism (VTE) on the short term after pregnancy and on the long term, that is, outside pregnancy, is largely unknown. We conducted a nationwide cohort study in women with at least 1 pregnancy and their first VTE risk by linking the Dutch perinatal registry (Perined) to anticoagulation clinics. We used Cox proportional hazard models to estimate hazard ratios (HRs) and corresponding 95% CI for VTE risk in women with hypertension during pregnancy, women with preeclampsia, compared with women with uncomplicated pregnancies (reference). A total of 1 919 918 women were followed for a median of 13.7 (interquartile range, 7.6–19.2) years for a total of 24 531 118 person-years in which 5759 first VTEs occurred; incidence rate: 2.3 (95% CI, 2.3–2.4) per 10 000 person-years. In the first pregnancy and 3-month postpartum period, VTE risk was higher in women with hypertension, HR, 2.0 (95% CI, 1.7–2.4), and highest among women with preeclampsia, HR, 7.8 (95% CI, 5.4–11.3), versus the reference group. On the long term, women with hypertension during pregnancy and preeclampsia had a higher VTE risk: HR, 1.5 (95% CI, 1.4–1.6) and HR, 2.1 (95% CI, 1.8–2.4), respectively, versus the reference group. When excluding events during pregnancy and postpartum, these HRs were 1.4 (95% CI, 1.3–1.5) and 1.6 (95% CI, 1.4–2.0), respectively. In conclusion, hypertension during pregnancy and preeclampsia are associated with an increased VTE risk during pregnancy and postpartum period and in the 13 years after.

The role of neutrophil activation in determining the outcome of pregnancy and modulation by hormones and/or cytokines

Neutrophils are often exclusively considered as a first-line innate immune defence, able to rapidly kill or trap pathogens and causing in case of over-activation tissue damage. In the female reproductive tract, however, the presence and activity of neutrophils seems to be tightly regulated. Major players in orchestrating this regulation are cyclical steroid sex hormones present during the menstrual cycle and pregnancy. This review describes the role of sex hormones in regulating directly or indirectly the functionality of neutrophils, the role of neutrophils during fertilization and pregnancy and in controlling viral, fungal and bacterial infection. This review also discusses the consequence of overt neutrophil activation in pregnancy pathologies.

Alteration of heat shock protein 20 expression in preeclamptic patients and its effect in vascular and coagulation function

Preeclampsia (PE) is a pregnancy-specific, multi-system disorder and the leading cause of maternal and perinatal morbidity and mortality in obstetrics worldwide. Excessive vasoconstriction and dysregulated coagulation function are closely associated with PE. Heat shock protein 20 (HSP20) is ubiquitously expressed under normal physiological conditions and has important roles in vascular dilatation and suppression of platelet aggregation. However, the role of HSP20 in the pathogenesis of PE remains unclear. In this study, we collected chorionic plate resistance arteries (CPAs) and serum from 118 healthy pregnant women and 80 women with PE and detected the levels of HSP20 and its phosphorylated form. Both HSP20 and phosphorylated HSP20 were downregulated in CPAs from women with PE. Comparison of the vasodilative ability of CPAs from the two groups showed impaired relaxation responses to acetyl choline in preeclamptic vessels. In addition to the reduced HSP20 in serum from women with PE, the platelet distribution width and mean platelet volume were also decreased, and the activated partial thromboplastin time and thromboplastin time were elevated.With regard to the vital roles of HSP20 in mediating vasorelaxation and coagulation function, the decreased HSP20 might contribute to the pathogenesis of PE.