Venous thromboembolism in relation to in vitro fertilization: an approach to determining the incidence and increase in risk in successful cycles

Venous thromboembolism associated with medically assisted reproduction (MAR): British fertility society policy and practice guidance for assessment and prevention

The association between Medically Assisted Reproduction (MAR) and thromboembolic complications has been reported widely in multiple published studies. Although venous thromboembolism (VTE) is not thought to be a common complication of MAR, it is associated with high morbidity and is often preventable. Since VTE usually occurs after completion of MAR treatment and is often managed outside of the treating fertility unit, these complications are likely to be underreported and there may be limited awareness of the risks among clinicians. As we continue to see a rise in the total number of MAR treatment cycles, particularly in women over 40 years of age, along with a steady increase in the number of fertility preservation cycles for both medical and social indications, it is likely that we will see an increase in absolute numbers of VTE complications. Currently, there is a lack of management guidance and reporting of VTE events associated with assisted conception treatment. The aim of this guidance is to provide clinicians with information on VTE risk factors, guidance on assessing VTE risk and the best practice recommendations on risk reducing strategies for individuals at risk of VTE undergoing ovarian stimulation and embryo transfer cycles.

Change of HeART: Cardiovascular Implications of Assisted Reproductive Technology

Cardiovascular (CV) disease is the leading cause of death in women, and it may manifest differently than in men, in part related to sex-specific CV risk factors. In females, assisted reproductive technologies (ARTs) are commonly used to treat infertility, and they utilize controlled ovarian stimulation involving the administration of exogenous sex hormones. ARTs, and especially controlled ovarian stimulation, have been associated with an increased pregnancy and short-term CV risk, although the long-term CV implications of these treatments in individuals treated with ARTs and their offspring remain unclear. This review endeavors to provide a comprehensive examination of what is known about the relationship between ART and CV outcomes for females treated with ARTs, as well as their offspring, and recommendations for future research. Novel insights into female-specific CV risk factors are critical to reduce the disproportionate burden of CV disease in Canadian women. ART has revolutionized reproductive medicine, offering hope to millions of individuals with infertility worldwide, and a further understanding of the CV implications of this important sex-specific CV risk factor is warranted urgently.

Managing Pulmonary Embolism With Right Ventricular Thrombus in In Vitro Fertilization-Related Pregnancy: A Clinical Insight

This case study provides an insightful examination of the management of high-risk pulmonary embolism (PE) in a 27-year-old pregnant patient following in vitro fertilization (IVF). Overlapping symptoms of PE and typical pregnancy manifestations, coupled with concerns about radiation exposure from diagnostic imaging, presented unique diagnostic challenges. Despite the heightened risk of thrombosis during pregnancy and elevated D-dimer levels, a conservative approach was strategically employed. This involved therapeutic anticoagulation using low-molecular-weight heparin, leading to significant patient improvement without the need for invasive interventions. This case highlights the imperative for a judicious yet proactive approach in managing PE among pregnant patients, meticulously considering both maternal and fetal health risks.

Swedish obstetric thromboprophylaxis guideline: background and update

Risk estimation concerning venous thromboembolism (VTE) and thromboprophylaxis for those at risk is routine in pregnancy. For 20 years, Swedish obstetricians have followed a weighted-risk algorithm guideline for risk estimation, based on which patient selection, timing, duration and dosage of thromboprophylaxis are determined. This article presents the latest update, the basis for the algorithm and its application for assessing moderate- to high obstetric VTE risk, defined as equal or greater absolute risk per time unit than the antepartum risk of women with one prior VTE. The risk score is based on risk factors conferring approximately fivefold increased risk of VTE or a multiple thereof. This article also presents algorithm efficacy data and describes lifestyle advice provided to patients. In our experience, the Swedish guideline for obstetric VTE risk estimation is easy to follow. It helps identify women at high risk. The risk of under- or overtreatment is thus minimised.

Venous Thromboembolism Associated with Assisted Reproductive Technology: A Systematic Review and Meta-analysis

BACKGROUND

 Hormonal exposure leads to an increased risk of venous thromboembolism (VTE) but the risk of VTE associated with assisted reproductive technology (ART) is not clearly determined.

METHODS

 We searched in PubMed, EMBASE, Web of Science, and the Cochrane Library databases and identified all relevant articles published up to February 1, 2021. The primary objective was to determine the frequency of VTE associated with ART. Secondary objectives were to determine (1) the risk of VTE associated with ART as compared to pregnancy without ART; (2) the risk of VTE associated with ovarian hyperstimulation syndrome (OHSS); and (3) to determine potential risk factors of VTE related to ART.

RESULTS

 Fourteen studies were included. The overall frequency of VTE associated with ART was 0.23% (95% confidence interval [CI]: 0.07-0.46). Women undergoing ART had a two- to threefold increased risk of VTE as compared to spontaneous pregnancy (relative risk [RR]: 2.66; 95% CI: 1.60-4.43). The overall frequency of VTE specifically related to OHSS was <0.001%. The risk of VTE after ART complicated by OHSS, as compared to ART without OHSS, was higher but not statistically significant (RR: 14.83; 95% CI: 0.86-255.62). Risk factors of VTE associated with ART were in vitro fertilization procedure (RR, odds ratio [OR], and hazard ratio varying from 1.77, 95% CI: 1.41-2.23 to 4.99, 95% CI: 1.24-20.05), hyperhomocysteinemia (OR: 15.2; 95% CI: 2.0-115.0), polycystic ovarian syndrome (PCOS) (RR: 4.8; 95% CI: 1.7-13.4), successful ART leading to pregnancy (OR: 13.94; 95% CI: 1.41-137.45).

CONCLUSION

 Further large prospective studies on risk factors of VTE in women undergoing ART are needed in order to optimize thromboprophylaxis in this context.

Right atrial thrombus and pulmonary thromboembolism related to ovarian hyperstimulation syndrome: A case report and literature review

A young lady with a history of infertility presented to the hospital with dyspnea and chest pain a few days after ovulation induction. Her manifestations were consistent with ovarian hyperstimulation syndrome (OHSS). Further investigations revealed right atrial thrombus and pulmonary thromboembolism. We successfully managed the condition with conservative therapy.

Pulmonary Embolism After in vitro Fertilization and Cesarean Section: Two Case Reports and Brief Review of the Literature

This paper reports two cases of postpartum pulmonary embolism in Taicang First People's Hospital affiliated to Soochow University. They share many similarities in age, fertilization way, birthing method, incidence of pulmonary embolism, treatment and prognosis. The main purpose is to inspire the current maternal PTE risk assessment, diagnosis and treatment, as well as to explore the existing limitations and problems.

Venous Thromboembolism Issues in Women

The lifetime risk of venous thromboembolism (VTE) is slightly higher in women than in men. There are several issues related to VTE that are unique to women. Combined hormonal contraceptives and pregnancy increase the risk of VTE in women of childbearing age, whereas hormone replacement therapy increases the VTE risk of postmenopausal women. Hereditary thrombophilia and risk factors such as older age, obesity, or smoking contribute to the risk increase. In women diagnosed with acute hormone-related VTE who are treated with oral anticoagulants, adequate contraception is mandatory to avoid unwanted pregnancies. According to current knowledge, hormonal contraception may be continued during anticoagulant therapy but must be switched to an estrogen-free contraception method at least 6 weeks before the termination of anticoagulation. VTE is also a major cause of maternal morbidity and mortality during pregnancy and the postpartum period. Currently, assisted reproduction technologies such as in vitro fertilization are widely used to treat couples affected by infertility. Complications of fertility treatment comprise VTE cases, especially in women with ovarian hyperstimulation syndrome. With this review, we intended to focus on VTE issues in women and summarize current evidence and guideline recommendations.

Emergency department utilization for ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a rare, but serious, risk of assisted reproductive technologies. In severe cases, patients may present to the emergency department (ED) for assessment, treatment of related complications, and even in-patient admission. Significant effort has been made to reduce the incidence and complications of OHSS; however, it is unknown if these strategies have decreased patient presentation for treatment in the ED.

PURPOSE

To assess ED utilization for OHSS over time and to examine admission rates, patient demographics, and charges.

METHODS

Retrospective longitudinal study utilizing data from the Nationwide Emergency Department Sample Database and the National ART Surveillance System. All ED visits between 2006 and 2016 with an ICD-9 or -10 diagnosis of OHSS were included. Demographics including age, geographic location, and income quartile and alternative diagnoses, admission rates, overall charges, and number of stimulation cycles annually were assessed.

RESULTS

The number of ovarian stimulation cycles steadily increased from 2006 (n = 110,183) to 2016 (n = 157,721), while the number of OHSS-related ED visits remained relatively stable (APC 2.08, p = 0.14). Admission rates for OHSS decreased from 52.7% in 2006 to 33.1% in 2016 (APC -4.43%, p < 0.01). The average charge for OHSS-related ED visits almost doubled from 2006 to 2016 (APC 8.53, p < 0.01) and was significantly higher than charges for non-OHSS-related visits for age-matched controls (p < 0.01).

CONCLUSION

Despite an increase in total stimulation cycles, there was no significant change in the estimated number of patients presenting to the ED; however, admission rates significantly declined. These observations suggest a possible shift in the severity and/or management of OHSS during the study period.

The Risk of Thrombosis Around Pregnancy: Where Do We Stand?

Pregnancy and puerperium increase the relative risk of venous thromboembolism (VTE) and the absolute risk remains low, around 1 per 1,000, with induced mortality of around 1 per 100,000. Analysis of large databases has helped specify the modes of presentation and risk factors (RF) whose impact is greater after than before childbirth, since VTE during pregnancy and post-partum obey different RFs. The evolution of the population concerned (mostly women over 35, obese, of multi-ethnicity undergoing medically assisted reproduction) affects the frequency of these RFs. Pulmonary embolism (PE) is over-represented after childbirth, but 30% of PE in pregnancy occurs without any RFs. Recommendations for prevention, mainly from expert groups, are heterogeneous and often discordant. Low molecular weight heparins (LMWH) are the mainstay of pharmacological thromboprophylaxis, in a field where randomized controlled studies are definitely lacking. VTE risk assessment in pregnancy must be systematic and repetitive. Risk assessment methods and scores are beginning to emerge to guide thromboprophylaxis and should be used more systematically. In the future, analyzing observational data from huge, nationwide registries and prospective cluster clinical trials may bring to light clinically relevant outcomes likely to feed comprehensive guidelines.

Ovarian hyperstimulation syndrome and adverse pregnancy outcome

INTRODUCTION

The aim of this study was to investigate the association between ovarian hyperstimulation syndrome (OHSS) and adverse pregnancy outcome.

EVIDENCE ACQUISITION

Medline, Embase and Cochrane databases were searched. The primary outcome was a composite score of adverse maternal outcome including either preterm birth (PTB), gestational diabetes mellitus (GDM), pre-eclampsia (PE) or pregnancy induced hypertension, intrahepatic cholestasis of pregnancy, thromboembolic events or need for caesarean section (CS). Secondary outcomes were a composite score of adverse fetal outcome including either miscarriage, low birthweight, fetal anomalies or intrauterine fetal death (IUD) and the individual components of both primary and secondary outcomes.

EVIDENCE SYNTHESIS

Thirteen studies (3303 ART pregnancies with and 89,720 without OHSS) were included. The risk of composite adverse maternal outcome (RR: 8.8, 95% CI: 8.1-9.5) was higher in women with compared to those without OHSS. The association between OHSS and adverse pregnancy outcome was mainly due to the higher risk of PTB (RR: 11.4, 95% CI: 10.5-12.4), while there was no difference in the risk of others primary outcome. Likewise, the risk of composite fetal outcome was higher in pregnancies with a prior OHSS (RR: 1.5, 95% CI: 1.1-2.0). The strength of association between OHSS and composite adverse maternal outcome persisted when considering singleton pregnancies or those with severe disease.

CONCLUSIONS

Pregnancies complicated by OHSS are at high risk of adverse pregnancy outcome, especially PTB.

Venous thromboembolism during pregnancy and postpartum period

Venous thromboembolism (VTE) is one of the leading causes of maternal mortality. Rates of VTE during pregnancy and the postpartum period have not decreased over the past two decades and pregnancyassociated VTE continues to pose a significant health challenge. Pregnant and postpartum women are at a higher risk for VTE owing to many factors. There are hormonally mediated and pregnancy-specific alterations of coagulation that favor thrombosis, including increased production of clotting factors. There are physiologic and anatomic mechanisms that also contribute, including a decreased rate of venous blood flow from the lower extemities as pregnancy progresses. Cesarean delivery also introduces VTE risk. In addition, studies have demonstrated that pregnancy-associated complications such as pre-eclampsia or peri-partum infections are associated with increased VTE rates. In this review, we discuss the recent epidemiological studies, pathogenesis, risk factors and clinical presentation as well as therapeutic options for VTE during pregnancy and the postpartum period. We also provide proposed diagnostic algorithms for diagnosis and management of VTE during pregnancy and the postpartum period based on updated evidence. Finally, we highlight knowledge gaps to guide future research.

Thrombophilia, Thrombosis and Thromboprophylaxis in Pregnancy: For What and in Whom?

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.

Prophylaxis and management of venous thromboembolism during pregnancy and postpartum period

Introduction. Venous thromboembolism (VTE) is one of the lead causes for maternal mortality and morbidity during pregnancy in the majority of developed countries. The incidence rate of VTE per pregnancy-year increases during pregnancy and postpartum period about by 4-fold and at least 14-fold, respectively.

Aim: to analyze and summarize current view on risk factors of thrombotic events during gestation and to discuss recent guidelines for the management of venous thromboembolic complications during pregnancy and postpartum, by taking into account a balance between risks and benefits of using anticoagulants.

Materials and Methods. The literature search covering the last 10 years was carried out in the electronic scientific databases RSCI, PubMed/MEDLINE, and Embase. While formulating a search strategy for evidence-based information, the PICO method (P = Patient; I = Intervention; C = Comparison; O = Outcome) and the key terms “venous thromboembolism” and “pregnancy” were used.

Results. Risk factors were found to include a personal history of VTE, verified inherited or acquired thrombophilia, a family history of VTE and general medical conditions, such as immobilization, overweight, varicose veins, some hematological diseases and autoimmune disorders. VTE is considered being potentially preventable upon prophylactic administration of anticoagulants, but no high confidence randomized clinical trials comparing diverse strategies of thromboprophylaxis in pregnant women have been proposed so far. Because heparins do not cross the placenta, weight-adjusted therapeutic-dose low molecular weight heparins (LMWH) represent the anticoagulant treatment of choice for VTE during pregnancy. Once- and twice-daily dosing regimens are acceptable. However, no evidence suggesting benefits for measurement of factor Xa activities and consecutive LMWH dose adjustments to improve clinical outcomes are available. In case of uncomplicated pregnancy-related VTE, no routine administration of vitamin K antagonists, direct thrombin or factor Xa inhibitors, fondaparinux, or danaparoid is recommended. Lactating women may switch from applying LMWH to warfarin. Anticoagulation therapy should be continued for 6 weeks postpartum with total duration lasting at least for 3 months.

Conclusion. VTE is a challenging task in pregnant women expecting to apply a multi-faceted approach for its efficient solution by taking into account updated recommendations and personalized patient-oriented features.

Ovarian Hyperstimulation: Diagnosis, Prevention, and Management

Ovarian hyperstimulation syndrome (OHSS) is a severe complication of controlled ovarian stimulation (COS). Pathogenesis of the disease is based on massive transudation of protein-rich fluid from the vascular compartment into the peritoneal, pleural and pericardial spaces, with a variable picture of clinical manifestations depending on its severity. Nowadays OHSS can easily be avoided by several prevention methods, ranging from identification of high-risk patients, choice of a correct protocol stimulation, trigger with gonadotropin-releasing hormone (GnRH) agonists or, finally, the freeze-all strategy. When OHSS occurs, it can usually be managed as outpatient care. Only if severe/critical cases are diagnosed hospitalization is necessary for appropriate rehydration, monitoring of fluid balance and eventual drainage of ascitic fluid. One of the most dangerous complications of OHSS is venous thromboembolism (VTE). Thromboprophylaxis has shown to be cost effective and widely used, while there are controversies regarding the usage of low dose aspirin (LDA) as a preventive measure.

Infertility, Infertility Treatment and Cardiovascular Disease: An Overview

The prevalence of maternal cardiovascular disease (CVD) has risen throughout the developed world, reflecting an increase in acquired cardiovascular risk factors, such as hypertension and diabetes, and the improved life expectancy of those living with congenital CVD due to advances in care. Because many cardiovascular risk factors or cardiovascular conditions are associated with infertility, reproductive-aged women with CVD may increasingly seek reproductive assistance. The worldwide use of assisted reproductive technologies (ART), such as in-vitro fertilization (IVF) with or without intracytoplasmic sperm injection, or intrauterine insemination following pharmacological ovulation induction have increased steadily over the last several decades. It is incumbent among providers who care for reproductive-aged women with pre-existing CVD or CVD risk factors to understand and appreciate the types of treatments offered and inherent risks related to infertility treatments, in order to guide their patients to making safe reproductive choices in line with their values and preferences. While infertility treatments increase the risk of complicated pregnancy, whether these risks are compounded among individuals with pre-existing CVD is less well known. In this review, we summarize current available evidence regarding short-term and long-term cardiovascular implications of ART among individuals with and without CVD, as well as treatment considerations for these women. Existing knowledge gaps and priority areas for further study are presented.

Prior Thromboembolic Disease and Assisted Reproductive Therapy

Assisted reproductive therapy (ART) increases the risk of venous thrombosis (VT) by 2- to 4-fold, whereas pregnancy increases the risk by 5- to 10-fold. Women with a history of VT undergoing ART are often suggested thromboprophylaxis. The literature is scarce and international guidelines are lacking. We made a review of the literature and base our suggestions primarily on expert opinions. We suggest women with a prior VT to use low-molecular-weight heparin as thromboprophylaxis starting from ovarian stimulation, throughout pregnancy, and 6 weeks postpartum. Assessment of VT risk should be done prior to ART. Adjustment of treatment to minimize the thrombotic risk, such as preventing ovarian hyperstimulation syndrome, single-embryo transfer, cryopreservation, and transfer of frozen embryos instead of fresh embryo in high-risk women, is suggested. Women with previous arterial thrombosis should continue aspirin during ART treatment, pregnancy, and postpartum.

The Pathophysiology of Hypercoagulability and Infertility

Alongside an interplay of a multitude of factors, attainment of a favorable pregnancy outcome is predicated on successful implantation, which in itself is a complex process anchored by balanced interchange with the hemostatic system. Among other etiologies, failure of implantation can result in infertility, and lead affected couples to consider assisted reproductive technology (ART) in an effort to fulfill their desire for procreation. Given the critical role of the hemostatic system in the process of implantation, documentation of a hypercoagulable state during controlled ovarian stimulation in the context of in vitro fertilization, as well as the potential association of its derangement in the setting of thrombophilia, with infertility, ART, ovarian hyperstimulation syndrome, and failure of implantation are explored. Additionally, current evidence addressing the relationship between ART and thromboembolism is examined, as is the role of therapy with heparin and aspirin to decrease thrombotic risk and improve ART-related pregnancy outcomes. Evidence-based recommendations from relevant professional societies are summarized.

Pulmonary Embolism in Pregnancy

Even though venous thromboembolism is a leading cause of maternal mortality in high-income countries, there are limited high-quality data to assist clinicians with the management of pulmonary embolism in this patient population. Diagnosis, prevention, and treatment of pregnancy-associated pulmonary embolism are complicated by the need to consider fetal, as well as maternal, well-being. Recent studies suggest that clinical prediction rules and D-dimer testing can reduce the need for diagnostic imaging in a subset of patients. Low-molecular-weight heparin is the preferred anticoagulant for both prophylaxis and treatment in this setting. Direct oral anticoagulants are contraindicated during pregnancy and in breastfeeding women. Thrombolysis or embolectomy should be considered for pregnant women with pulmonary embolism complicated by hemodynamic instability. Treatment of pregnancy-associated pulmonary embolism should be continued for at least 3 months, including 6 weeks postpartum. Management of anticoagulants at the time of delivery should involve a multidisciplinary individualized approach that uses shared decision making to take patient and caregiver values and preferences into account.

Incidence of and risk factors for thromboembolism during pregnancy and postpartum: A 10-year nationwide population-based study

OBJECTIVE

Knowledge of the incidence of pregnancy-related thromboembolism and its risk factors is clinically important because thromboembolism is the leading cause of maternal death. However, there are insufficient large population-based studies on this topic. The purpose of this study was to estimate the incidence of and identify the risk factors for thromboembolism during pregnancy and puerperium.

MATERIALS AND METHODS

We analyzed data from 2007 to 2016 using the Health Insurance Review and Assessment Service (HIRA) database. Women who gave birth in the Republic of Korea were identified. Thromboembolism was defined as the simultaneous presence of both the diagnostic and test codes. Risk factors for thromboembolism were identified using logistic regression.

RESULTS

A total of 1,188 delivery episodes with thromboembolism were extracted from 4,243,393 delivery episodes. The incidence of thromboembolism was 0.28 per 1,000 deliveries, and it increased over the 10-year period. The incidence of antepartum thromboembolism was 0.1 per 1,000 deliveries (418 cases), and the incidence of postpartum thromboembolism was 0.18 per 1,000 deliveries (770 cases). Thromboembolism was associated with ovarian hyperstimulation syndrome, low socioeconomic status, multiple birth, cesarean birth, preeclampsia, postpartum hemorrhage, placenta previa, advanced maternal age, hyperemesis and primiparity. The factors associated with mortality from thromboembolism were cesarean birth and preterm premature rupture of membranes.

CONCLUSION

The incidence of pregnancy-related thromboembolism increased over the 10-year study period. Low socioeconomic status, ovarian hyperstimulation syndrome, cesarean delivery and premature rupture of membranes were high-risk factors. This study provides an important reference for thromboprophylaxis for pregnancy-related thromboembolism.

Cardiovascular problems associated with IVF therapy

We are now in the beginning of the fifth decade of in vitro fertilization (IVF) with more than ten million children born and an annual growth rate of half a million. It was recently found that there is a sevenfold increase in the incidence of pulmonary embolism (PE) during the first trimester of an IVF pregnancy as compared to spontaneous pregnancy. PE is a major cause of maternal mortality, and it is thus of outmost importance to understand the pathophysiological mechanism. The oestrogen surge during the ovarian stimulation has been hypothesized to be the initiating pathophysiological event. A support of this is a current report showing that embryo transfer performed directly after ovarian stimulation increased the risk of PE more than eightfold, whereas no such increase was noted after delayed embryo transfer. This increased risk coincides with a persisting increased oestrogen level. Further reported cardiovascular problems are arterial thromboses, pre-eclampsia and gestational hypertension. Global haemostasis tests change in the direction of increased coagulability, but mostly within normal limits. Cell-bound haemostasis and in particular platelet activation are less studied. However, a major increase in the number of microvesicles (MVs) and markers indicating platelet activation was reported during ovarian stimulation. We now need longitudinal data concerning haemostatic variables that extends into the first trimester. A major research focus should be to identify biomarkers that could be used already before instigation of IVF. Another way to avoid risk could be to delay embryo transfer by adapting a freeze-all strategy.

The freeze-all strategy after IVF: which indications?

The freeze-all strategy is gaining popularity worldwide as an alternative to the conventional fresh embryo transfer. It consists of cryopreservation of the entire embryo cohort and the embryo transfer in a subsequent cycle that takes place separately from ovarian stimulation. The freeze-all strategy was initially a 'rescue' strategy for women at high risk of ovarian hyperstimulation syndrome; however, this approach has been extended to other indications as a scheduled strategy to improve implantation rates. This assumes that ovarian stimulation can alter endometrial receptivity in fresh cycles owing to the effect of supraphysiological levels of steroids on endometrial maturation. The procedure, however, has not been associated with increased live birth rates in all infertile couples, and concerns have been raised about the occurrence of several adverse perinatal outcomes. It is, therefore, crucial to identify in which subgroups of patients a freeze-all strategy could be beneficial. The aim of this review is to summarize current scientific research in this field to highlight potential indications for this strategy and to guide clinicians in their daily practice.

Incidence of pulmonary and venous thromboembolism in pregnancies after in vitro fertilization with fresh respectively frozen-thawed embryo transfer: Nationwide cohort study

BACKGROUND

The assisted reproductive technique in vitro fertilization (IVF) is associated with an increased risk of venous thromboembolism (VTE) and pulmonary embolism (PE) during the first trimester.

OBJECTIVES

To compare the incidence of VTE and PE during the first trimester of IVF pregnancies using fresh or frozen-thawed embryo transfer to that during natural pregnancies.

PATIENT/METHODS

Nationwide Swedish registry-based cohort study of women who gave birth (n = 902 891) at the age of 15-50 years to their first child from the 1st of January 1992 until the 31st of December 2012. Exposure groups were IVF with fresh respectively frozen-thawed embryo transfer. Incidences of VTE and PE were calculated, and time-varying hazard ratios estimated for all trimesters after fresh respectively frozen-thawed embryo transfer IVF and compared to natural conception.

RESULTS AND CONCLUSION

Women giving birth after fresh embryo transfer IVF had a more than eightfold increased incidence of venous thromboembolism (hazard ratio [HR] 8.96, 95% CI 6.33 to 12.67) and pulmonary embolism during the first trimester, (HR 8.69, 95% CI 3.83 to 19.71) compared to women giving birth after natural conception. The incidence of VTE in women giving birth after frozen-thawed embryo transfer was not increased during the first trimester. To conclude, fresh embryo transfer IVF was associated with a significantly increased incidence of VTE and PE during the first trimester. These results suggest that frozen-thawed embryo transfer could be a preferred method of IVF with a minimised maternal risk.

Venous thromboembolism in women: new challenges for an old disease

In countries that have controlled classic causes of maternal death, such as eclampsia and hemorrhage, venous thromboembolism (VTE) has become the major concern. Prevention of VTE during pregnancy and postpartum by applying guidelines and implementing pharmacoprophylaxis is still the best strategy to reduce occurrence of this complication. Hormonal contraceptives and hormone replacement therapy also increase the risk of VTE, but women cannot be deprived of their benefits, which increase their freedom at childbearing age and reduce their symptoms at menopause. Both indiscriminate use and unmotivated prohibition are inappropriate. Contraceptive and hormone replacement methods should be chosen with care, evaluating the patients’ contraindications, eligibility criteria, and autonomy. This article presents a nonsystematic review of recent literature with the aim of evaluating and summarizing the associations between VTE and clinical situations peculiar to women.

Prevention of Venous Thromboembolism during Pregnancy and the Puerperium with a Special Focus on Women with Hereditary Thrombophilia or Prior VTE-Position Paper of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH)

Venous thromboembolism (VTE) is a major cause of maternal morbidity during pregnancy and the postpartum period. Because there is a lack of adequate study data, management strategies for the prevention of VTE during pregnancy have mainly been deduced from case-control and observational studies and extrapolated from recommendations for non-pregnant patients. The decision for or against pharmacologic thromboprophylaxis must be made on an individual basis weighing the risk of VTE against the risk of adverse side effects such as severe bleeding complications. A comprehensive, multidisciplinary approach is often essential as the clinical scenario is made more complex by the specific obstetric context, especially in the peripartum period. As members of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH), we summarize the evidence from the available literature and aim to establish a more uniform strategy for VTE risk assessment and thromboprophylaxis in pregnancy and the puerperium. In this document, we focus on women with hereditary thrombophilia, prior VTE and the use of anticoagulants that can safely be applied during pregnancy and the lactation period.

Assisted reproduction and thromboembolic risk in the COVID-19 pandemic

The COVID-19 pandemic has significantly increased mortality in many countries, with the number of infected cases increasing exponentially worldwide. One of the main determining factors of the poor prognosis in these patients is the development of coagulopathy. Moreover, it is well known that assisted reproductive technology procedures confer a risk of thromboembolic complications. This commentary analyses specific aspects coexisting between the thrombotic risk described during virus infection and that reported in the context of assisted reproduction treatments. Based on known pathophysiological aspects of virus infection and of ovarian stimulation, there are common elements that deserve to be taken into account. In the present context, any risk of hyperstimulation should be avoided. Gonadotrophin-releasing hormone agonist triggering should be mandatory in high-responder patients and/or those with COVID-19 infection. In both cases, the cycle should be segmented. A proposal is made for the use of prophylactic low molecular weight heparin not only in those cases in which oocyte retrieval has been performed, but also in those in which cancellation has been decided. In addition, endometrial preparation for frozen-thawed embryo transfers should use the transdermal route in order to minimize the higher thrombotic risk associated with the oral route.

Pregnancy and cardiovascular disease

Cardiovascular disease complicates 1-4% of pregnancies - with a higher prevalence when including hypertensive disorders - and is the leading cause of maternal death. In women with known cardiovascular pathology, such as congenital heart disease, timely counselling is possible and the outcome is fairly good. By contrast, maternal mortality is high in women with acquired heart disease that presents during pregnancy (such as acute coronary syndrome or aortic dissection). Worryingly, the prevalence of acquired cardiovascular disease during pregnancy is rising as older maternal age, obesity, diabetes mellitus and hypertension become more common in the pregnant population. Management of cardiovascular disease in pregnancy is challenging owing to the unique maternal physiology, characterized by profound changes to multiple organ systems. The presence of the fetus compounds the situation because both the cardiometabolic disease and its management might adversely affect the fetus. Equally, avoiding essential treatment because of potential fetal harm risks a poor outcome for both mother and child. In this Review, we examine how the physiological adaptations during pregnancy can provoke cardiometabolic complications or exacerbate existing cardiometabolic disease and, conversely, how cardiometabolic disease can compromise the adaptations to pregnancy and their intended purpose: the development and growth of the fetus.

Prophylaxis and Therapy of Venous Thrombotic Events (VTE) in Pregnancy and the Postpartum Period

Venous thromboembolisms and pulmonary embolisms are one of the main causes of morbidity and mortality in pregnancy. The increased risk of thrombotic events caused by the physiological changes during pregnancy alone does not justify any medical antithrombotic prophylaxis. However, if there are also other risk factors such as a history of thromboses, hormonal stimulation as part of fertility treatment, thrombophilia, increased age of the pregnant woman, severe obesity or predisposing concomitant illnesses, the risk of thrombosis should be re-evaluated - if possible by a coagulation specialist - and drug prophylaxis should be initiated, where applicable. Low-molecular-weight heparins (LMWH) are the standard medication for the prophylaxis and treatment of thrombotic events in pregnancy and the postpartum period. Medical thrombosis prophylaxis started during pregnancy is generally continued for about six weeks following delivery due to the risk of thrombosis which peaks during the postpartum period. The same applies to therapeutic anticoagulation after the occurrence of a thrombotic event in pregnancy; here, a minimum duration of the therapy of three months should also be adhered to. During breastfeeding, LMWH or the oral anticoagulant warfarin can be considered; neither active substance passes into breast milk.

Case-based discussion on the implications of exogenous estrogens in hemostasis and thrombosis: the obstetrician's view

This is the obstetrician's view on 3 different clinical scenarios involving bleeding and thrombotic disorders. In the first scenario, an 18 year old with a history of heavy menstrual bleeding since menarche presents with abdominal pain and ultrasound findings suggestive of a hemorrhagic ovarian cyst. The association with an underlying bleeding disorder is recognized. The goals of management, which are controlling hemorrhage and preserving fertility, are stated. Ovarian suppression, the most effective method to prevent recurrent hemorrhagic ovarian cysts, is outlined. Long-term management of heavy menstrual bleeding with hormonal contraception is described. In the second scenario, the same patient returns 5 years later for a preconception visit. The potential risks to an unborn baby with von Willebrand disease (VWD) are addressed. The natural rise in von Willebrand factor (VWF) during pregnancy is discussed, but the fact that women with VWD do not achieve the same VWF levels as women without VWD is emphasized and the implications are presented. In anticipation of pregnancy, the need for nonhormonal management of heavy menstrual bleeding and hemorrhagic ovarian cysts is mentioned. In the third and final scenario, the patient's cousin with factor V Leiden seeks consultation regarding the risks of thrombosis with in vitro fertilization. The steps of assisted reproductive technology are described. The strategies to prevent venous thromboembolism by preventing ovarian hyperstimulation and reducing the likelihood of multiple gestation are detailed.

Low molecular weight heparins use in pregnancy: a practice survey from Greece and a review of the literature

Background

Use of LMWH in pregnancy is not only limited to VTE management, but it extends, to the management of vascular gestational complications and the optimization of IVF pregnancies despite the lack of concrete scientific evidence. In this context, we conducted the present study aiming to gain insights regarding the use of LMWH during pregnancy and puerperium. We recorded indication for use, diagnostic work-up as well as the safety and efficacy of the treatment, trying to elucidate the clinical practice in our country.

Methods

We analyzed data regarding 818 pregnant women received LMWH during 2010-2015.Our cohort had a median age of 33.9 years and a BMI of 23.6.There were 4 groups: those with a history of VTE [Group-A: 76], those with pregnancy complications [Group-B: 445], those undergoing IVF [Group-C: 132] and those carrying prothrombotic tendency (thrombophilia, family history of VTE, other) [Group-D: 165]. Mean duration of LMWH administration was 8.6 ± 1.5 months. Out of the total number, 440 received LMWH in fixed prophylactic dose, 272 in higher prophylactic-weight adjusted dose and 106 in therapeutic dose. Moreover, 152 women received in addition low-dose acetylsalicylic acid (ASA). 93.8% of pregnancies were single and 6.2% were multiple ones. Live births occurred in 98.7% of pregnancies.

Results

Anticoagulation was efficacious and well tolerated. Seventeen VTE events were recorded; 7 of them antepartum and 10 postpartum. No major bleeding events were observed while 13 clinical relevant non-major bleeding events were recorded. Regarding gestational vascular complications, 28 IUGR events were recorded, as well as 48 cases of preterm labor of which 12 were concomitant with IUGR (25%). Six early pregnancy losses were recorded; there were 3 fetal deaths and 3 cases of pre-eclampsia/eclampsia.

Conclusions

LMWHs are used extensively during pregnancy and puerperium in Greece for VTE treatment and prophylaxis and for a variety of other indications as well. Although the drug has been shown to be both safe and efficacious, its use for some indications has no proven scientific evidence. In order to clearly define the role of LMWHs in pregnancy, beyond thromboprophylaxis, large prospective studies are required, which could be based on the conclusions of this study.

American Society of Hematology 2018 guidelines for management of venous thromboembolism: venous thromboembolism in the context of pregnancy

BACKGROUND

Venous thromboembolism (VTE) complicates ∼1.2 of every 1000 deliveries. Despite these low absolute risks, pregnancy-associated VTE is a leading cause of maternal morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians and others in decisions about the prevention and management of pregnancy-associated VTE.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The McMaster University GRADE Centre supported the guideline development process, including updating or performing systematic evidence reviews. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

The panel agreed on 31 recommendations related to the treatment of VTE and superficial vein thrombosis, diagnosis of VTE, and thrombosis prophylaxis.

CONCLUSIONS

There was a strong recommendation for low-molecular-weight heparin (LWMH) over unfractionated heparin for acute VTE. Most recommendations were conditional, including those for either twice-per-day or once-per-day LMWH dosing for the treatment of acute VTE and initial outpatient therapy over hospital admission with low-risk acute VTE, as well as against routine anti-factor Xa (FXa) monitoring to guide dosing with LMWH for VTE treatment. There was a strong recommendation (low certainty in evidence) for antepartum anticoagulant prophylaxis with a history of unprovoked or hormonally associated VTE and a conditional recommendation against antepartum anticoagulant prophylaxis with prior VTE associated with a resolved nonhormonal provoking risk factor.

Life-threatening complications among women with severe ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome is a potentially life-threatening clinical condition.

OBJECTIVE

The objective of this study was to evaluate risk factors for life-threatening complications for patients with severe ovarian hyperstimulation syndrome in a United States nationwide sample.

MATERIALS AND METHODS

Ovarian hyperstimulation syndrome admissions from 2002 to 2011 from the Nationwide Inpatient Sample were included in this study. The association between patient and hospital factors and life-threatening complications (deep vein thrombosis/pulmonary embolism, acute respiratory distress syndrome, acute renal failure, intubation), nonroutine discharge (discharge to skilled nursing facility, transfer hospital), prolonged length of stay, and total hospital charges were analyzed. Survey-adjusted multivariable logistic regression analyses were performed for these outcomes, controlling for risk factors, with adjusted odds ratios with 95% confidence intervals as the measures of effect.

RESULTS

A total of 11,562 patients were hospitalized with severe ovarian hyperstimulation syndrome from 2002 to 2011. The majority were white (55.7%), with private insurance (87.7%), aged 25-39 years (84.6%), and hospitalized in an urban location (95%). In all, 19.3% of patients had medical comorbidities including hypertension, diabetes, obesity, hypothyroidism, and anemia. Life-threatening complications occurred in 4.4% of patients (deep vein thrombosis/pulmonary embolism, 2.2%; acute renal failure; acute respiratory distress syndrome, 0.9%; intubation, 0.5%). Patients ≥40 years old (odds ratio, 4.02; 95% confidence interval, 1.37, 11.76), those with comorbidities (odds ratio, 2.29; 95% confidence interval, 1.46, 3.57), and African American patients (odds ratio, 2.15; 95% confidence interval, 1.25, 3.70) were more likely to develop life-threatening conditions. Patients with medical comorbidities (odds ratio, 0.39; 95% confidence interval, 0.24, 0.63) were also less likely to be routinely discharged from the hospital. Adjusting for patient and hospital demographics, patients with comorbidities were more likely to develop deep vein thrombosis/pulmonary embolism (adjusted odds ratio, 2.44; 95% confidence interval, 1.28, 4.65) and acute renal failure (adjusted odds ratio, 2.26; 95% confidence interval, 1.21, 4.23). Patients who developed life-threatening complications had longer hospital length of stay (adjusted odds ratio, 3.72; 95% confidence interval, 2.28, 6.07) and higher hospital costs (adjusted odds ratio, 5.20; 95% confidence interval, 3.22,8.39).

CONCLUSION

Patients with common medical comorbidities are at higher risk for life-threatening complications in the setting of severe ovarian hyperstimulation syndrome. Furthermore, these complications are associated with high hospital costs and hospital burden. Given the increasing number of in vitro fertilization patients with medical comorbidities, closer monitoring of at-risk patients may be indicated. As assisted reproductive technology practice changes in recent years with strategies designed to reduce ovarian hyperstimulation syndrome risk, future studies are needed to assess the impact of these changes on hospitalization and complication risk.

An enhanced clot growth rate before in vitro fertilization decreases the probability of pregnancy

Background

The shift towards hypercoagulation during in vitro fertilization (IVF) can lead to the impairment of embryo implantation and placental blood circulation, which is believed to be a factor in an unsuccessful IVF cycle.

Objectives

To assess coagulation in women with infertility before the start of an IVF cycle and during treatment to reveal the association between coagulation imbalance and IVF outcome.

Patients/Methods

We conducted a prospective cohort observational study including 125 participants who underwent fresh IVF cycles. Blood samples were collected at five time points: before IVF, one week after the start of controlled ovarian stimulation (COS), on the day of follicular puncture, on the day of embryo transfer (ET) and one week after ET. Coagulation tests (clotting times: activated partial thromboplastin time (APTT) and prothrombin; fibrinogen and D-dimer concentrations; thrombodynamics) were performed.

Results

Women with an elevated clot growth velocity (>32.3 μm/min, detected by thrombodynamics) before IVF demonstrated a higher risk of negative IVF outcomes (adjusted RR = 1.38; 95% CI 1.28–1.49; P<0.001). During the procedure, we observed increases in prothrombin, fibrinogen and D-dimer concentrations, a slight shortening of APTT and a hypercoagulation shift in the thrombodynamics parameters. The hemostasis assay values during COS and after ET had no associations with IVF outcomes.

Conclusions

Hypercoagulation in the thrombodynamics before the start of IVF treatment was associated with negative IVF outcomes. After the start of COS, all tests demonstrated a hypercoagulation trend, but the hypercoagulation did not influence IVF outcome. This research is potentially beneficial for the application of thrombodynamics assay for monitoring hemostasis in infertile women prior to an IVF procedure with the goal of selecting a group requiring hemostasis correction to increase the chances of pregnancy.

Towards complication-free assisted reproduction technology

Assisted reproductive technology (ART) has vastly improved over the last 40 years, from a frequently unsuccessful and complicated procedure requiring hospital admission and routine laparoscopy to a fairly simple outpatient technique with relatively high success rates. However, it is important to stress that ART is not without risk and medical complications may still occur. The incidence of most of these ART-related complications is associated with how women undergo ovarian stimulation. For this reason, physicians should be aware that a carefully thought-out ovarian stimulation protocol and cycle monitoring are of paramount importance to maximise the success of the treatment while avoiding potentially life-threating complications to occur in this frequently otherwise healthy patient population. This review discusses the rationale and evolution of ovarian stimulation strategies over the years and the current developments towards finding a balance between the retrieval of a sufficient number of oocytes and ART-related complication prevention.

Multimodality imaging of acute locoregional and systemic complications in the setting of assisted reproduction

Over the past 40 years since the first in vitro fertilization was performed, both the role of assisted reproductive technology (ART) in establishing viable pregnancy as well as the available treatment options have expanded enormously. Annually in the USA, nearly 2% of pregnancies now employ some form of ART assistance, with in vitro fertilization (IVF) being the most commonly utilized methodology. Both maternal and fetal risks are elevated in ART pregnancies, the latter including adverse outcome due to both increased gestational number as well as advanced maternal age. Maternal risks may be divided into locoregional and systemic complications. Adverse pelvic complications include those relating to gamete harvesting and transfer, ovarian hyperstimulation, the sequela of ectopic and heterotopic pregnancies, as well as ovarian torsion, all of which are elevated in the ART cohort. Ovarian hyperstimulation syndrome is the most commonly encountered complication, with both systemic and pelvic features relating to increased vascular permeability, hemoconcentration, and ascites. While life-threatening cases are relatively rare, moderate and severe manifestations may occur in up to 10% of ART cycles and, as such, are a not infrequent cause for ER visitation. Familiarity with the clinical and imaging manifestations of ART complications as well as their prognostic implications will facilitate a timely diagnosis and assist the interpreting radiologist in best expediting appropriate clinical care. In this article, we will briefly discuss the current methodology of ART then present an imaging-based multimodality review of the potentially encountered adverse maternal sequela, highlighting key diagnostic features and differential considerations as well as potential prognostic implications.

Obstetric venous thromboembolism: a systematic review of dalteparin and pregnancy

A systematic review of studies published between 1 January 1985 and 31 August 2017 was performed to analyse the efficacy of the low-molecular-weight heparin, dalteparin, in venous thromboembolism (VTE) treatment and prophylaxis during pregnancy, and to evaluate dosing practices, anticoagulant monitoring and adverse events. A therapeutic dosing throughout pregnancy or followed by reduced doses effectively prevented VTE recurrence. Anti-factor Xa activity was the most commonly used method of dose monitoring. The risk of bleeding with dalteparin was generally minor. Major bleeding was observed when a high dose of dalteparin was employed during (or close to) delivery, or postpartum. Other adverse events were minor. Disparity exists in VTE treatment and thromboprophylaxis, with wide variety in the dosing regimens, treatment strategies and monitoring practices employed. Large randomised controlled trials are warranted but due to ethical reasons, and the rarity of VTE-associated obstetric complications, case-control, registry and large observational studies present more likely options.

Does low-dose aspirin improve pregnancy rate in women undergoing frozen-thawed embryo transfer cycle? A pilot double-blind, randomized placebo-controlled trial

AIM

To evaluate the effect of adjuvant low-dose aspirin therapy on clinical pregnancy rate and uterine perfusion in women undergoing frozen-thawed embryo transfer (FET) cycles.

METHODS

This study was performed as a pilot randomized, double-blind placebo-controlled trial, from May 2012 to February 2015. Overall, 60 available eligible women who were candidates for FET were randomly assigned to two groups receiving either 100 mg oral aspirin (n =30) or placebo (n =30). The primary outcome measure was clinical pregnancy rate. Secondary outcome measures were pulsatility index (PI), resistance index (RI), implantation rate, live birth rate and miscarriage rate.

RESULTS

There was no significant difference in endometrial thickness, PI and RI. However, the study group had higher rates of clinical pregnancy, implantation, live birth (P = 0.042, P = 0.031 and P = 0.007, respectively) and lower rate of miscarriage (P = 0.020) as compared to the control group. Twin birth rate was comparable between the two groups.

CONCLUSION

Our pilot study demonstrated that administration of low-dose aspirin in FET cycles results in better pregnancy, implantation and live birth rates without changing the uterine hemodynamics or endometrial thickness. However, further randomized clinical studies in larger populations are needed to confirm these findings.