Strategies for diagnosis and prevention of venous thromboembolism during pregnancy

Management of Acute Saddle Pulmonary Embolism in Pregnancy Following Fetal Surgery

A 33-year-old gravidity three parity three (G3P3) woman at 34 weeks of pregnancy underwent fetal surgery to repair an open lumbosacral myelomeningocele at 22 weeks gestation and experienced preterm premature rupture of membranes as a result. She developed a saddle pulmonary embolus with signs of right heart strain while on prolonged bed rest. She was treated emergently with aspiration thrombectomy and suprarenal inferior vena cava (IVC) filter placement, followed by an uncomplicated cesarean delivery thereafter.

Venous Thromboembolism in Pregnancy: Challenges and Solutions

Venous thromboembolism (VTE) is a serious medical condition that can lead to severe morbidity and mortality, making it a significant public health concern. VTE is a multifactorial condition that results from the interaction of genetic, acquired, and environmental factors. Physiological changes during pregnancy increase the risk of VTE as they express Virchow's triad (increased coagulation factors, decreased fibrinolysis, trauma, and venous stasis). Moreover, pregnancy-related risk factors, such as advanced maternal age, obesity, multiple gestations, and cesarean delivery, further increase the risk of VTE. Managing VTE in pregnancy is challenging due to the complexity of balancing the risks and benefits of anticoagulant therapy for both the mother and the fetus. A multidisciplinary approach involving obstetricians, hematologists, and neonatologists, is necessary to ensure optimal outcomes for both the mother and baby. This review aims to discuss the current challenges associated with VTE in pregnancy and identify potential solutions for improving outcomes for pregnant women at risk for VTE.

Maternal mortality following thromboembolism; incidences and prophylaxis strategies

BACKGROUND

Thromboembolism is one of the main causes of maternal mortality, which can be prevented in many cases. The present study was designed to investigate the incidence and prophylaxis strategies for maternal mortality following thromboembolism in postnatal.

METHODS

In this case series study, the data of the mortality cases were extracted according to the ethical and security standards of the Ministry of Health of the country and compared with a healthy control group. The thromboembolism risk factors measured and scored using a questionnaire entitled "the evaluation of risk factors for maternal mortality following thromboembolism during pregnancy, labor, or post-partum".

RESULTS

The maternal mortality rate was 16 per 100,000 live births. Among 297 mortality cases, 27 (9%) death were due to thromboembolism. The mean gestational age was 32.5 weeks. Dyspnea (88.8%) and tachycardia (18.5%) were found as common clinical manifestations in these patients. Sixteen cases (59.3%) did not get heparin, 6 (22.2%) received single dose and 5 (18.5%) received two doses and more. In these 11 cases, 5 (45%) patients received heparin before surgery, 1 after surgery, and 5 before and after surgery. Twenty cases deceased in the first hours after delivery and the rest after 2 to 12 days. The average score of risk for thromboembolism based on Royal College of Obstetricians & Gynecologist (RCOG) guideline was 4.6.

CONCLUSION

It seems that one of the most important cause of maternal mortality in this study was the lack of recognition of high-risk patients and the lack of prescription for prophylaxis with heparin and this clearly explains the need for accurate screening of high-risk mothers, designing a standard form and the care and treatment of these patients.

Knowledge, Awareness and Risk of Occurrence of Venous Thromboembolism of Perinatal Women

PURPOSE

The purpose of this study is to identify knowledge, awareness, and risk of occurrence of venous thromboembolism among pregnant women.

METHODS

Subjects were 106 pregnant women treated as inpatients and outpatients at a women's health hospital in a metropolitan city February 19-March 22, 2018. Instruments consisted of questionnaires that included knowledge, awareness, and risk of occurrence of venous thromboembolism queries. Collected data were analyzed by t-test, one-way analysis of variance, Mann-Whitney U test and Kruskal-Wallis test.

RESULTS

Mean score of subjects' knowledge of venous thromboembolism was 4.47 (0-15), mean score of subjects' awareness of venous thromboembolism was 66.98 (25-100), and mean score of subjects' risk factor of venous thromboembolism was 0.98 (0-44). CONCLUSIONS: Pregnant women's level of knowledge and awareness of prevention and risk factors on venous thromboembolism, is significantly low. To raise their awareness of risk symptoms and prevent occurrence of the disease, it is essential for nurses as well as medical staffs to: 1) provide an educational program on venous thromboembolism for patients; 2) assess and monitor pregnant women with a risk factor of venous thromboembolism; and 3) implement proper prophylaxis for patients.

Association between prophylactic low-molecular-weight heparin use in pregnancy and macrosomia: analysis of the Ottawa and Kingston birth cohort

Essentials Low-molecular-weight heparin (LMWH) is used to prevent venous thromboembolism (VTE) in pregnancy. We evaluated the association between LMWH and large for gestational age (LGA) infants. We found no significant associations between LMWH use and LGA. LMWH does not appear to increase the risk for the delivery of an LGA infant. SUMMARY: Background Low-molecular-weight heparin (LMWH), an anticoagulant, is the recommended drug for thromboprophylaxis and treatment of venous thromboembolism (VTE) in pregnancy. During pregnancy, LMWH is routinely prescribed to mothers with an increased risk of VTE or with a history of thrombosis. Although clinical reports of larger offspring born to women administered LMWH have been noted, no studies to date have evaluated or associated the use of LMWH and large for gestational age (LGA) infants. Objectives To determine whether there is an association between LMWH usage in mothers and the prevalence of LGA. Patients/Methods We performed an analysis of the Ottawa and Kingston (OaK) Birth Cohort and report characteristics of LMWH and association LGA (> 10%ile). We used coarsened exact matching (CEM) methods to account for bias and confounding. Results A total of 7519 women from the OaK Birth Cohort were included; 59 were administered LMWH during pregnancy (0.78%). Mothers prescribed LMWH had significantly greater BMI (P = 0.0001), age (P = 0.0001) and parity (P = 0.02). Gestational length was shorter among women administered LMWH compared to those without treatment (37.7 ± 2.0 vs. 39.2 ± 2.0, P < 0.0001), an iatrogenic finding. The odds ratio of an LGA delivery among women administered LMWH was 1.02 (95% confidence interval [CI], 0.48-2.16; P = 0.96) in unadjusted analyses and was 1.15 (95% CI, 0.49-2.71) in the matched sample adjusted for maternal age, BMI and gestational age. Conclusions These results, although exploratory, provide indirect evidence of no increased risk of LGA infants among women prescribed LMWH.

Physical Exertion Immediately Prior to Placental Abruption: A Case-Crossover Study

While there is consistent evidence that episodes of physical exertion are associated with an immediately higher risk of acute ischemic vascular events, the risk of placental abruption immediately following episodes of physical exertion has not been studied. In a multicenter case-crossover study, we interviewed 663 women with placental abruption at 7 Peruvian hospitals between January 2013 and August 2015. We asked women about physical exertion in the hour before symptom onset and compared this with their frequency of physical exertion over the prior week. Compared with times with light or no exertion, the risk of placental abruption was 7.8 (95% confidence interval (CI): 5.5, 11.0) times greater in the hour following moderate or heavy physical exertion. The instantaneous incidence rate ratio of placental abruption within an hour of moderate or heavy physical exertion was lower for women who habitually engaged in moderate or heavy physical activity more than 3 times per week in the year before pregnancy (rate ratio (RR) = 3.0, 95% CI: 1.6, 5.9) compared with more sedentary women (RR = 17.3, 95% CI: 11.3, 26.7; P for homogeneity < 0.001), and the rate ratio was higher among women with preeclampsia/eclampsia (RR = 13.6, 95% CI: 7.0, 26.2) than among women without (RR = 6.7, 95% CI: 4.4, 10.0; P for homogeneity = 0.07).

A Unique Recombinant Fluoroprobe Targeting Activated Platelets Allows In Vivo Detection of Arterial Thrombosis and Pulmonary Embolism Using a Novel Three-Dimensional Fluorescence Emission Computed Tomography (FLECT) Technology

Progress in pharmaceutical development is highly-dependent on preclinical in vivo animal studies. Small animal imaging is invaluable for the identification of new disease markers and the evaluation of drug efficacy. Here, we report for the first time the use of a three-dimensional fluorescence bioimager called FLuorescence Emission Computed Tomography (FLECT) for the detection of a novel recombinant fluoroprobe that is safe, easily prepared on a large scale and stably stored prior to scan. This novel fluoroprobe (Targ-Cy7) comprises a single-chain antibody-fragment (scFv_Targ), which binds exclusively to activated-platelets, conjugated to a near-infrared (NIR) dye, Cy7, for detection. Upon mouse carotid artery injury, the injected fluoroprobe circulates and binds within the platelet-rich thrombus. This specific in vivo binding of the fluoroprobe to the thrombus, compared to its non-targeting control-fluoroprobe, is detected by the FLECT imager. The analyzed FLECT image quantifies the NIR signal and localizes it to the site of vascular injury. The detected fluorescence is further verified using a two-dimensional IVIS^® Lumina scanner, where significant NIR fluorescence is detected in vivo at the thrombotic site, and ex vivo, at the injured carotid artery. Furthermore, fluorescence levels in various organs have also been quantified for biodistribution, with the highest fluoroprobe uptake shown to be in the injured artery. Subsequently, this live animal imaging technique is successfully employed to monitor the response of the induced thrombus to treatment over time. This demonstrates the potential of using longitudinal FLECT scanning to examine the efficacy of candidate drugs in preclinical settings. Besides intravascular thrombosis, we have shown that this non-invasive FLECT-imaging can also detect in vivo pulmonary embolism. Overall, this report describes a novel fluorescence-based preclinical imaging modality that uses an easy-to-prepare and non-radioactive recombinant fluoroprobe. This represents a unique tool to study mechanisms of thromboembolic diseases and it will strongly facilitate the in vivo testing of antithrombotic drugs. Furthermore, the non-radiation nature, low-cost, high sensitivity, and the rapid advancement of optical scanning technologies make this fluorescence imaging an attractive development for future clinical applications.

The potential of target-specific oral anticoagulants for the acute and long-term treatment of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) comprises both deep vein thrombosis and pulmonary embolism. VTE is a leading cause of morbidity and mortality worldwide and its increasing incidence and prevalence are a major health concern. The primary medical objective during the acute phase of VTE treatment is to prevent thrombus extension and embolization. Extended treatment aims to prevent or minimize long-term complications, such as recurrent VTE, post-thrombotic syndrome and chronic thromboembolic pulmonary hypertension.

SCOPE

Anticoagulant therapy has been the mainstay of treatment for VTE and traditionally involves initial therapy with heparin, overlapping with and followed by a vitamin K antagonist. Although effective, standard heparin/vitamin K antagonist therapy has several limitations that can be overcome by more recently developed target-specific oral anticoagulants (TSOACs). These agents have predictable pharmacokinetics, a rapid onset of action and few drug-drug or drug-food interactions. Furthermore, TSOACs offer convenient anticoagulation without the need for routine coagulation monitoring and dose adjustment.

FINDINGS

The efficacy and safety data from phase III clinical trials support the use of TSOACs for VTE treatment, including in special patient populations. Risk-stratification tools and strategies have been developed to assist physicians in managing anticoagulation treatment.

CONCLUSIONS

Rivaroxaban is the first TSOAC to gain widespread approval for the treatment of acute deep vein thrombosis and pulmonary embolism and the long-term prevention of recurrent VTE as monotherapy. Dabigatran has also been approved for this indication recently. TSOACs, especially as monotherapy, represent a paradigm shift in clinical practice for the management of patients with VTE.

Use of fibrin monomer complex for screening for venous thromboembolism in the late pregnancy and post-partum period

AIM

We measured fibrin monomer complex (FMC) levels in all subjects who gave birth at our hospital and evaluated the feasibility of using FMC for screening for venous thromboembolism (VTE) in patients during late pregnancy and the post-partum period.

METHODS

From August 2010 to January 2012, all women who gave birth at our hospital were included. FMC and D-dimer levels were determined during the late pregnancy and post-partum periods. Compression ultrasonography of the lower extremities was performed in women with high FMC values.

RESULTS

Of the 673 women enrolled, measurements were performed in 595 women (88.4%) during late pregnancy and in 610 women (90.6%) during the post-partum period. The FMC levels were normal during late pregnancy in 400 women (67.2%) and during the post-partum period in 399 women (78.5%) having vaginal delivery and 83 women (81.4%) who underwent a cesarean section. The FMC levels were abnormal during late pregnancy in 50 women (8.4%) and during the post-partum period in nine women (1.8%) having vaginal delivery and in none (0%) who underwent a cesarean section. Ultrasonography detected thrombi in three (6.0%) women during late pregnancy. The FMC levels were strongly correlated with D-dimer levels (R = 0.726, P < 0.0001, in late pregnancy; and R = 0.888, P < 0.0001, in the post-partum period following vaginal delivery).

CONCLUSION

FMC levels could identify pregnancy-related abnormalities requiring compression ultrasonography examination, without changing the cut-off values for non-pregnant individuals. Thus, this marker may be used to screen for VTE.

Body weight gain and serum leptin levels of non-overweight and overweight/obese pregnant women

Background

Our objective was to evaluate changes in serum leptin levels during pregnancy in overweight/obese and non-obese women and to assess total and percent weight gain during pregnancy as possible factors that influence leptin levels.

Material/Methods

In a prospective study of 42 low-risk pregnant women receiving prenatal care, we assessed serum leptin levels at gestational weeks 9–12, 25–28, and 34–37. Based on their pre-pregnancy body mass indices (BMIs), the cohort was divided into: non-overweight (BMI <25 kg/m²) and overweight/obese (BMI ≥25 kg/m²) subjects.

Results

We found a progressive increase in maternal weight gain during pregnancy in both groups. There was also a progressive increase in leptin levels in the 2 strata; however, the increase was significantly higher in the non-overweight patient group. We found that non-overweight pregnant women had a noticeably larger total weight gain. When analyzing the percent weight gain during pregnancy compared to the pre-pregnancy weight, the non-overweight group had a significantly greater percent weight gain than the overweight/obese group.

Conclusions

Our results suggest that the greater increase in leptin levels in non-overweight pregnant women can be explained by the higher percent weight gain in this group compared to overweight/obese women. These findings suggest that controlling the percent weight gain may be an important preventive measure when controlling leptin levels during pregnancy and subsequent medical complications.

Anticoagulant treatment of pulmonary embolism: impact and implications of the EINSTEIN PE study

Pulmonary embolism (PE), which can develop as a consequence of deep vein thrombosis (DVT), is a serious and potentially fatal venous thromboembolic event. Patients with PE are at increased risk of venous thromboembolism (VTE) recurrence and serious complications such as chronic thromboembolic pulmonary hypertension. Anticoagulants, namely heparins and vitamin K antagonists (VKAs), have been the main treatments for PE in patients who are haemodynamically stable. However, use of these agents can be complex and is associated with an increased risk of bleeding (a characteristic that is common to all anticoagulants). Simplified, effective treatment regimens for PE would be very beneficial for patients, physicians and payers. Compared with DVT, PE is a different clinical manifestation of VTE; phase III trials have now started to focus specifically on patients with PE. Trials in patients with PE can provide further information on the optimal management of these patients. Results of the phase III EINSTEIN PE study demonstrated non-inferiority in the efficacy and safety of oral rivaroxaban compared with standard of care (enoxaparin/VKA) for the treatment of patients with acute symptomatic PE (with or without symptomatic DVT). Rates of major bleeding were significantly lower in patients receiving rivaroxaban. This review will discuss the findings of recent trials, particularly the potential impact of single, oral agents for both the initial and long-term treatment of a range of patients with PE, and how these results may influence the clinical management of PE.