Epidemiology of venous thromboembolism (VTE) associated with pregnancy

Incidence of maternal venous thromboembolism in China: A systematic review and meta-analysis

BACKGROUND

Venous thromboembolism (VTE) is one of the primary causes of maternal death. Although many studies have reported maternal VTE, no study has estimated the incidence of it in China.

OBJECTIVES

The aim of this work was to estimate the incidence of maternal VTE in China and to compare the risk factors for it.

SEARCH STRATEGY

The authors searched eight platforms and databases including PubMed, Embase, and Cochrane Library from inception to April 2022, with the search terms "venous thromboembolism" AND "puerperium (pregnancy)" AND "incidence" AND "China."

SELECTION CRITERIA

Studies provide data to calculate the incidence of maternal VTE among Chinese patients.

DATA COLLECTION AND ANALYSIS

The authors made a standardized table to collect data and calculated the incidence and 95% confidence intervals (CIs), founding source of heterogeneity by subgroup analysis and meta-regression and judging publication bias by funnel plot and Egger test.

MAIN RESULTS

The included 53 papers with a total sample size of 3 813 871 patients had 2539 cases of VTE, and the incidence of maternal VTE in China was 0.13% (95% CI, 0.11-0.16; P < 0.001).

CONCLUSIONS

The trend in the incidence of maternal VTE in China is stable. Cesarean section and advanced age are associated with a higher incidence of VTE.

Induction or spontaneous labor for pregnant patients on anticoagulants?

OBJECTIVE

There are two approaches to peripartum management for pregnant patients undergoing anticoagulation treatments: spontaneous labor or scheduling an induction. A long interval without anticoagulation is a thrombosis risk factor, while a short interval leads to risks of delivery without epidural analgesia or post partum hemorrhage. Our objective was to evaluate the impact of planned induction versus spontaneous labor on obtaining neuraxial analgesia.

MATERIALS AND METHODS

A retrospective single-center study was conducted from 2012 to 2020 including all patients on preventive or curative low molecular-weight heparin at the time of delivery, excluding planned cesarean sections. The rates of neuraxial analgesia were compared between two groups: spontaneous labor and induction, as well as the intervals without anticoagulants.

RESULTS

127 patients were included. In the spontaneous labor group, 78% (44/56) received neuraxial analgesia versus 88% (37/42) in the induction group (p = 0.29). For curative dose treatment, the rate of neuraxial analgesia was 45,5% in the spontaneous group versus 78,6% (p = 0.12). The median time without anticoagulation was 34 h [26-46] in the spontaneous labor group and 43 h [34-54] in the induction group (p = 0.01), without an increased incidence of thrombosis. The rate of postpartum hemorrhage did not differ between the two groups.

CONCLUSION

Planned induction tended to increase the rate of neuraxial analgesia, without reaching significance, and most women in spontaneous labor accessed analgesia. Peripartum management should be a shared decision with the patient considering the obstetrical and thrombosis risk context for each patient.

Antiphospholipid syndrome management: a 2023 update and practical algorithm-based approach

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS) is an acquired thrombo-inflammatory disease that has morbid and sometimes devastating effects on patients and their families. This review will discuss the most recent international societal treatment guidelines and propose practical management algorithms for various APS sub-types.

RECENT FINDINGS

APS represents a disease spectrum. Although thrombosis and pregnancy morbidities are traditional hallmarks of APS, a variety of extra-criteria clinical phenotypes can often be seen, which makes clinical management more challenging. Primary APS thrombosis prophylaxis should take a risk-stratified approach. Although vitamin K antagonists (VKAs) or heparin/low molecular weight heparin (LMWH) remain the preferred treatment for secondary APS thrombosis prophylaxis, some international society guidelines support the use of direct oral anticoagulants (DOACs) in certain circumstances. Careful monitoring and individualized obstetric care with the use of aspirin and heparin/LMWH will improve pregnancy outcomes among pregnant individuals with APS. Treatment of microvascular and catastrophic APS remains challenging. While the addition of various immunosuppressive agents is often utilized, further systemic evaluations of their use are warranted before definitive recommendations can be made. Several new therapeutic strategies are on the horizon that might enable more personalized and targeted APS management in the near future.

SUMMARY

Although the knowledge of APS pathogenesis has grown in recent years, the management principles and strategies are largely unchanged. There is an unmet need for evaluating pharmacological agents, beyond anticoagulants, that target diverse thromboinflammatory pathways.

Thrombin, protein C, and protein S values in mother-infant dyads in the postpartum period

INTRODUCTION

The objective of the study was to establish the normal range for the levels of antithrombin (AT), protein C (PC), and protein S (PS) in the first week post birth in mother-infant pairings, adjusting for obstetric and perinatal factors, based on 2 different laboratory methods.

METHODS

Determinations were carried out in 83 healthy term neonates and their mothers, establishing 3 postpartum age groups: 1-2 days, 3 days, and 4-7 days.

RESULTS

There were no differences in the levels of any of the proteins between the different age groups in neonates or mothers in the first week post birth. The adjusted analysis found no association with obstetric or perinatal factors. The AT and PC levels were higher in mothers compared to infants (P < .001), while the PS levels were similar in both. Overall, the correlation of maternal and infant protein values was poor, except for the levels of free PS in the first 2 days after delivery. Although we found no differences based on which of the 2 laboratory methods was applied, the absolute values did differ.

The effect of low molecular weight heparin combined with air pressure in the prevention of lower extremity venous thrombosis after cesarean section: A single-center retrospective study

In this study, we investigated the effect of low-molecular-weight heparin combined with pneumatic pressure in preventing lower extremity deep vein thrombosis after cesarean section, as well as on the visual analog scale (VAS) score. 120 women who underwent cesarean sections at full term in our hospital from January 2019 to January 2022 were included and divided into a control group (55 cases) and an observation group (65 cases) based on the different treatment methods: the control group was treated with low-molecular-weight heparin and the observation group was treated with pneumatic compression therapy based on the control group. The 2 groups were analyzed for thrombosis, clinical efficacy of the treatment methods, and VAS scores. The incidence of deep vein thrombosis in the observation group were significantly lower than in the control group (4.62% vs 21.82%, P < .05). There were no statistically significant differences in activated partial thromboplastin time, prothrombin time, and thrombin time between the 2 groups (P > .05) before treatment; however, after treatment, activated partial thromboplastin time, prothrombin time, and thrombin time in the observation group were significantly higher than those in the control group (P < .05). The clinical efficacy was significantly higher in the observation group compared with the control group (95.38% vs 78.18%, respectively). The VAS scores in the observation group were significantly lower than those in the control group (P < .05). Hence, low-molecular-weight heparin combined with pneumatic pressure therapy significantly reduces the incidence of lower limb deep vein thrombosis after cesarean section. It also improves the coagulation index and reduces post-operative pain. Therefore, it should be considered for use in clinical practice.

SARS-CoV-2 in Pregnancy, Birth and Puerperium. Guideline of the DGGG und DGPM (S2k-Level, AWMF Registry Number 015/092, March 2022)

Objective This S2k guideline of the German Society for Gynecology and Obstetrics (DGGG) and the German Society of Perinatal Medicine (DGPM) contains consensus-based recommendations for the care and treatment of pregnant women, parturient women, women who have recently given birth, and breastfeeding women with SARS-CoV-2 infection and their newborn infants. The aim of the guideline is to provide recommendations for action in the time of the COVID-19 pandemic for professionals caring for the above-listed groups of people.

Methods The PICO format was used to develop specific questions. A systematic targeted search of the literature was carried out using PubMed, and previously formulated statements and recommendations issued by the DGGG and the DGPM were used to summarize the evidence. This guideline also drew on research data from the CRONOS registry. As the data basis was insufficient for a purely evidence-based guideline, the guideline was compiled using an S2k-level consensus-based process. After summarizing and presenting the available data, the guideline authors drafted recommendations in response to the formulated PICO questions, which were then discussed and voted on.

Recommendations Recommendations on hygiene measures, prevention measures and care during pregnancy, delivery, the puerperium and while breastfeeding were prepared. They also included aspects relating to the monitoring of mother and child during and after infection with COVID-19, indications for thrombosis prophylaxis, caring for women with COVID-19 while they are giving birth, the presence of birth companions, postnatal care, and testing and monitoring the neonate during rooming-in or on the pediatric ward.

A retrospective study on the use of low-molecular-weight heparin for prevention of pregnancy-related recurrent venous thromboembolism and obstetrical complications

BACKGROUND

The risk of venous thromboembolism (VTE) is increased during pregnancy and it is further increased together with pregnancy complications in women with personal history of VTE and thrombophilia abnormalities. It is unclear how the use of low-molecular-weight heparin (LMWH) may prevent such complications.

OBJECTIVE

To evaluate the potential benefits and risks of the use of LMWH for prevention of pregnancy-related VTE and obstetrical complications in the first pregnancy after a previous VTE.

METHODS

This retrospective cohort study includes fertile women referred to the Thrombosis Center from January 2000 to September 2018 for a thrombophilia work-up, after having had at least one previous VTE and one pregnancy thereafter. Data on pregnancy-related recurrent VTE, pregnancy outcomes and the use of LMWH were collected.

RESULTS

Among 208 women, no thrombosis or major bleeding was recorded in 138 pregnancies conducted with LMWH, whereas 10 VTE (14%) were recorded in 70 pregnancies conducted without. Nine women (90%) with recurrent VTE had had a previous hormone-related event. The incidence of miscarriage was lower in pregnancies with LMWH than in those without (11% vs. 26%, relative risk 0.4, 95% confidence interval: 0.2-0.8), whereas late obstetrical complications and terminations were similar in the two groups. The prevalence of terminations was doubled in women with thrombophilia (12%) than in those without (6%).

CONCLUSIONS

LMWH prophylaxis during pregnancy appears to be effective and safe for the prevention of recurrent VTE and may reduce the incidence of miscarriage.

Autoimmune disease and risk of postpartum venous thromboembolism

Background

The risk of pregnancy-related mortality in the United States has nearly doubled since 1990, with venous thromboembolism (VTE) accounting for approximately 10% of these deaths.

Objectives

The objective of this study was to assess whether preexisting autoimmune disease is a risk factor for postpartum VTE.

Methods

Using the MarketScan Commercial and Medicare Supplemental administrative databases, a retrospective cohort study analyzed whether postpartum persons with autoimmune disease had a higher risk of postpartum VTE incidence than postpartum persons without autoimmune disease. Using International Classification of Diseases codes, we identified 757,303 individuals of childbearing age who had a valid delivery date with at least 12 weeks of follow-up.

Results

Individuals were, on average, 30.7 years old (SD, 5.4), and 3.7% (N = 27,997 of 757,303) of them had evidence of preexisting autoimmune disease. In covariate-adjusted models, postpartum persons with preexisting autoimmune disease had higher rates of postpartum VTE than postpartum persons without autoimmune disease (hazard ratio [HR], 1.33; 95% CI, 1.07-1.64). When analyzed by individual autoimmune disease, those with systemic lupus erythematosus (HR, 2.49; 95% CI, 1.47-4.21) and Crohn's disease (HR, 2.49; 95% CI, 1.34-4.64) were at an elevated risk of postpartum VTE compared with those without autoimmune disease.

Conclusion

Autoimmune disease was associated with a higher rate of postpartum VTE, with evidence that the association was most pronounced among individuals with systemic lupus erythematosus and Crohn's disease. These findings suggest that postpartum persons of childbearing age with autoimmune disease may require more monitoring and prophylactic care after delivery to prevent potentially fatal VTE events.

Maternal mortality related to pulmonary embolism in the United States, 2003-2020

BACKGROUND

Pulmonary embolism is a leading cause of maternal morbidity and mortality in Western countries. In the United States, pulmonary embolism-related mortality rates have plateaued in the general population after an initial decrease in the past 20 years.

OBJECTIVE

This study aimed to describe the changes in pulmonary embolism-related maternal mortality rates in the United States over the past 2 decades.

STUDY DESIGN

In this epidemiologic study of public vital registration data (death certificates encompassing underlying and contributing causes of death) from the Centers for Disease Control and Prevention Multiple Cause of Death database (2003-2020), we identified all maternal deaths with a pulmonary embolism code listed in any position of the death certificates. We investigated the changes in annual crude pulmonary embolism-related maternal mortality rates for the years 2003 to 2020, considering the effect of the introduction of the pregnancy checkbox in death certificates on the pulmonary embolism-related maternal mortality rates.

RESULTS

Overall, 735 pulmonary embolism-related maternal deaths out of 12,871 total maternal deaths (5.7%) were recorded between 2003 and 2020; the overall pulmonary embolism-related maternal mortality rate was 1.02 (95% confidence interval, 0.95-1.10) per 100,000 live births. The pulmonary embolism-related maternal mortality rate increased from 0.93 in 2003 to 1.96 in 2020; however, when accounting for the implementation of the pregnancy checkbox in the death certificates, the trends in pulmonary embolism-related maternal mortality were largely unchanged from 2003 to 2020. The crude pulmonary embolism-related maternal mortality rates differed across maternal age groups (overall 0.61, 1.09, and 3.83 maternal deaths per 100,000 live births for those aged ≤24, 25-39, and ≥40 years, respectively) and racial/ethnicity groups (2.89, 0.47, 0.77, and 0.63 maternal deaths per 100,000 live births for Black non-Hispanics, other non-Hispanics, White non-Hispanics, and Hispanics, respectively).

CONCLUSION

Maternal mortality rates related to pulmonary embolism did not decrease during the period from 2003 to 2020, as opposed to mortality rates related to pulmonary embolism in the general population. More research is required to assess whether improvement in venous thromboembolism prevention and pulmonary embolism diagnosis and management strategies might reduce death owing to pulmonary embolism in this vulnerable population.

Venous Thromboembolism During Pregnancy and the Postpartum Period: Risk Factors, Diagnostic Testing, and Treatment

Importance

The risk of venous thromboembolism (VTE) increases during pregnancy and the postpartum period. Deep vein thrombosis is the most common VTE during pregnancy, but pulmonary embolism is typically of greater concern as it contributes to far higher morbidity and mortality. Diagnosis and treatment of VTE during pregnancy differ substantially from the general nonpregnant population.

Objective

This review describes the epidemiology, risk factors, clinical presentation, diagnosis, and treatment of VTE during pregnancy and the postpartum period.

Evidence Acquisition

First, we reviewed the VTE guidelines from professional societies in obstetrics, cardiology, hematology, emergency medicine, pulmonology, and critical care. Second, we examined references from these documents and used PubMed to identify recent articles that cited the guidelines. Finally, we searched PubMed and Google Scholar for articles published since 2018 that included terms for pregnancy and the epidemiology, risk factors, diagnostic imaging, or treatment of VTE.

Results

Venous thromboembolism risk increases throughout pregnancy and peaks shortly after delivery. More than half of pregnancy-related VTE are associated with thrombophilia; other major risks include cesarean delivery, postpartum infection, and the combination of obesity with immobilization. Most VTE can be treated with low molecular weight heparin, but cases of limb- or life-threatening VTE require consideration of thrombolysis and other reperfusion therapies.

Conclusions and Relevance

Venous thromboembolism is far more frequent in antepartum and postpartum women than age-matched controls, and clinical suspicion for VTE in this population should incorporate pregnancy-specific risks. Treatment of limb- or life-threatening antepartum or postpartum VTE requires multispecialty coordination to optimize maternal and fetal outcomes.

Venous thrombosis risk factors in pregnant women

Venous thromboembolism (VTE) is the third most common cause of death on Earth after myocardial infarctions and strokes, according to the World Health Organization (WHO). Pregnancy is a unique condition of woman, when enormous changes occur in functioning of the most important systems of homeostasis in a relatively short time. These are physiological hypercoagulation, slowing of blood flow, increase in circulating blood volume, etc. However, while being physiological, these changes increase the risks of venous thromboembolism by almost 6 times. In some cases, there appears an imbalance or dissociation between the functioning of natural antithrombotic systems and the activation of coagulation as a consequence of genetically or acquired determined causes (genetic thrombophilia, antiphospholipid syndrome, comorbidities, obstetric complications and other exogenous and endogenous factors). Accordingly, identification of risk factors, their systematization, and determination of VTE risks in pregnancy and puerperium is one of the most important tasks of clinical medicine. Various recommendations have appeared for practitioners during the last 10-15 years on the basis of the risk factors analysis in order to prevent VTE in pregnant women more effectively. Nevertheless, none of these recommendations can yet take into account all risk factors, although convenient scoring systems have emerged for risk assessment and clear recommendations on anti-thrombotic prophylaxis regimens in risk groups in recent years. This article will review historical understanding of thrombosis in pregnant women, progress in understanding VTE risk factors in pregnant women, and available reserves in identifying new risk factors during pregnancy and puerperium in order to stratify risks more efficiently.

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.

How can Secondary Thromboprophylaxis in High-Risk Pregnant Patients be Improved?

Low-molecular-weight heparin (LMWH) is suggested for thromboprophylaxis in pregnant women with previous venous thromboembolism (VTE). Anyway, there is only limited amount of studies evaluating the effect of LMWH on hemostatic parameters during pregnancy of patients with previous VTE and the need of secondary thromboprophylaxis. We therefore provide results of prospective and longitudinal assessment of changes in hemostasis in high-risk pregnant women at four times during pregnancy (T1–T4) and one time after the postpartum period (T5) used for individualized modification of thromboprophylaxis. In this study, the results of coagulation factor VIII (FVIII) and protein S (PS) activity, ProC Global ratio and anti-Xa activity were evaluated. Despite the thromboprophylaxis, an increased predisposition to thromboembolic complications was detected (significant increase in FVIII activity and decrease in PS function, ProC Global ratio not normalized even after the postpartum period – p < .0001 between controls and T5 for PS and ProC Global). These results indicate that hemostasis may not be restored even 6 to 8 weeks after delivery and pose the question when is it safe to withdraw the anticoagulant thromboprophylaxis in high-risk patients with prior VTE.

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.

Position Paper on the Management of Pregnancy-Associated Superficial Venous Thrombosis. Balkan Working Group for Prevention and Treatment of Venous Thromboembolism

Venous thromboembolism (VTE) is a multifactorial disease that can possibly affect any part of venous circulation. The risk of VTE increases by about 2 fold in pregnant women and VTE is one of the major causes of maternal morbidity and mortality. For decades superficial vein thrombosis (SVT) has been considered as benign, self-limiting condition, primarily local event consequently being out of scope of well conducted epidemiological and clinical studies. Recently, the approach on SVT has significantly changed considering that prevalence of lower limb SVT is twice higher than both deep vein thrombosis (DVT) and pulmonary embolism (PE). The clinical severity of SVT largely depends on the localization of thrombosis, when it concerns the major superficial vein vessels of the lower limb and particularly the great saphenous vein. If untreated or inadequately treated, SVT can potentially cause DVT or PE. The purpose of this review is to discuss the complex interconnection between SVT and risk factors in pregnancy and to provide evidence-based considerations, suggestions, and recommendations for the diagnosis and treatment of this precarious and delicate clinical entity.

Association Between Maternal Weight Gain in Different Periods of Pregnancy and the Risk of Venous Thromboembolism: A Retrospective Case-Control Study

BACKGROUND

Venous thromboembolism (VTE) remains an important cause of maternal deaths. Little is known about the associations of specific periods of gestational weight gain (GWG) with the category of VTE, pulmonary embolism (PE), or deep venous thrombosis (DVT) with or without PE.

METHODS

In a retrospective case-control study conducted in Shanghai First Maternity and Infant Hospital from January 1, 2017 to September 30, 2021, cases of VTE within pregnancy or the first 6 postnatal weeks were identified. Controls without VTE were randomly selected from women giving birth on the same day as the cases, with 10 controls matched to each case. Total GWG and rates of early, mid, and late GWG values were standardized into z-scores, stratified by pre-pregnant body mass index (BMI). The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated through multivariate logistic regression models.

RESULTS

There were 196 cases (14.4 per 10,000) of VTE within pregnancy or the first 6 postnatal weeks were identified. Higher total weight gain was associated with increased risks of PE (aOR, 13.22; 95% CI, 2.03-85.99) and VTE (OR, 10.49; 95% CI, 1.82-60.45) among women with underweight. In addition, higher total weight gain was associated with increased risk of PE (aOR, 2.06; 95% CI, 1.14-3.72) among women with healthy weight. Similarly, rate of higher early weight gain was associated with significantly increased risk for PE (aOR, 2.15; 95% CI, 1.05-4.42) among women with healthy BMI. The lower rate of late weight gain was associated with increased risks of PE (aOR, 7.30; 95% CI, 1.14-46.55) and VTE (OR, 7.54; 95% CI, 1.20-47.57) among women with underweight. No significant associations between maternal rate of mid GWG and increased risk for any category of VTE, PE, or DVT with or without PE were present, regardless of maternal pre-pregnant BMI.

CONCLUSION

The GWG associations with the category of VTE, PE, or DVT with or without PE differ at different periods of pregnancy. In order to effectively improve maternal and child outcomes, intensive weight management that continues through pregnancy may be indispensable.

Safety and Efficacy of Endovascular Treatment on Pregnancy-Related Iliofemoral Deep Vein Thrombosis

Objective: This study investigates the safety and efficacy of endovascular treatments on pregnancy-related iliofemoral deep vein thrombosis (DVT). Methods: We retrospectively reviewed data of 46 patients who had symptomatic pregnancy-related iliofemoral DVT and underwent endovascular treatment. The patients treated with catheter-directed thrombolysis (CDT) were classified as the CDT group. In contrast, those treated with CDT combined with pharmacomechanical thrombectomy (PMT) or angioplasty/stenting were classified as the pharmacomechanical catheter-directed thrombolysis (PCDT) group. Results: Based on the immediate post-operative clot burden reduction rate analysis of 46 patients: 22 cases were completely dissolved (lysis grades III), 12 were partially dissolved (lysis grades II), and 12 failed (lysis grades I). There was a statistically significant difference in the rate of clot burden reduction between the CDT group (n = 19) and the PCDT group (n = 27) (p = 0.001). There was no statistically significant difference in the number of bleeding events between the two groups (p = 0.989). At 24 months, cumulative venous patency in the CDT group was 50.0%, compared to 78.2% in the PCDT group. Furthermore, there was a statistically significant difference in Villalta score (p = 0.001) and venous severity scoring (VCSS score) (p = 0.005) between the two groups. Conclusions: CDT treatment combined with PMT or angioplasty/stenting is comparatively safe and effective for pregnant-related DVT patients. PCDT outperforms CDT in terms of immediate efficacy and reduces the incidence of post-thrombotic syndrome with better midterm outcomes.

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.

Proteinuria and venous thromboembolism in pregnancy: a population-based cohort study

Background

Pregnancy-associated venous thromboembolism (VTE) is associated with high morbidity and mortality. Identification of risk factors of VTE may lead to improved maternal and foetal outcomes. Proteinuria confers a pro-thrombotic state, however, its association with VTE in pregnancy remains unknown. We set out to assess the association of proteinuria and VTE during pregnancy.

Methods

We conducted a population-based, retrospective cohort study of all pregnant women (≥16 years of age) with a proteinuria measure within 20 weeks of conception (n = 306 244; mean age 29.8 years) from Ontario, Canada. Proteinuria was defined by any of the following: urine albumin:creatinine ratio ≥3 mg/mmol, urine protein:creatinine ratio ≥5 mg/mmol or urine dipstick proteinuria ≥1. The main outcome measure was a diagnosis of VTE up to 24-weeks post-partum.

Results

A positive proteinuria measurement occurred in 8508 (2.78%) women and was more common with a history of kidney disease, gestational or non-gestational diabetes mellitus and hypertension. VTE events occurred in 625 (0.20%) individuals, with a higher risk among women with positive proteinuria [32 events (0.38%)] compared with women without proteinuria [593 events (0.20%); inverse probability-weighted risk ratio 1.79 (95% confidence interval 1.25-2.57)]. The association was consistent using a more specific VTE definition, in the post-partum period, in high-risk subgroups (hypertension or diabetes) and when the sample was restricted to women with preserved kidney function.

Conclusions

The presence of proteinuria in the first 20 weeks of pregnancy is associated with a significantly higher risk of VTE.

The interrelationship between pregnancy, venous thromboembolism, and thyroid disease: a hypothesis-generating review

Pregnancy induces physiological changes that affect the risk of thrombosis and thyroid disease. In this hypothesis-generating review, the physiological changes in the coagulation system and in thyroid function during a normal pregnancy are described, and the incidence of venous thromboembolism (VTE) and thyroid disease in and after a pregnancy are compared and discussed. Furthermore, evidence regarding the association between thyroid disease and VTE in non-pregnant individuals is scrutinized. In conclusion, a normal pregnancy entails hormonal changes, which influence the onset of VTE and thyroid disease. Current evidence suggests an association between thyroid disease and VTE in non-pregnant individuals. This review proposes the hypothesis that maternal thyroid disease associates with VTE in pregnant women and call for future research studies on this subject. If an association exists in pregnant women specifically, such findings may have clinical implications regarding strategies for thyroid function testing and potential thromboprophylaxis in selected individuals.

Society of Family Planning clinical recommendations: Management of individuals with bleeding or thrombotic disorders undergoing abortion

Individuals who have bleeding disorders, thrombophilias, a history of venous thromboembolism (VTE), or who are taking anticoagulation medication for other reasons may present for abortion. Clinicians should be aware of risk factors and histories concerning for excessive bleeding and thrombotic disorders around the time of abortion. This document will focus on how to approach abortion planning in these individuals. For first-trimester abortion, procedural abortion (sometimes called surgical abortion) is generally preferred over medical management for individuals with bleeding disorders or who are on anticoagulation. First-trimester procedural abortion in an individual on anticoagulation can generally be done without interruption of anticoagulation. The decision to interrupt anticoagulation for a second-trimester procedure should be individualized. Individuals at high risk for VTE can be offered anticoagulation post-procedure. Individuals with bleeding disorders or who are anticoagulated can safely be offered progestin intrauterine devices. Future research is needed to better assess quantitative blood loss and complications rates with abortion in these populations.

Venous thrombosis risk factors in pregnant women

OBJECTIVES

Assess all risk factors of venous thromboembolism (VTE) in pregnancy and puerperium.

METHODS

Different guidelines for VTE prevention have been analyzed.

RESULTS

Various recommendations have appeared for practitioners during the last 10-15 years on the basis of the risk factors analysis in order to prevent VTE in pregnant women more effectively. Nevertheless, none of these recommendations can yet take into account all risk factors, although convenient scoring systems have emerged for risk assessment and clear recommendations on anti-thrombotic prophylaxis regimens in risk groups in recent years.

CONCLUSIONS

VTE is the third most common cause of death on Earth after myocardial infarctions and strokes, according to the World Health Organization. Pregnancy is a unique condition of woman, when enormous changes occur in functioning of the most important systems of homeostasis in a relatively short time. These are physiological hypercoagulation, slowing of blood flow, increase in circulating blood volume, etc. However, while being physiological, these changes increase the risks of venous thromboembolism by almost six times. In some cases, there appears an imbalance or dissociation between the functioning of natural antithrombotic systems and the activation of coagulation as a consequence of genetically or acquired determined causes (genetic thrombophilia, antiphospholipid syndrome, comorbidities, obstetric complications and other exogenous and endogenous factors). Accordingly, identification of risk factors, their systematization, and determination of VTE risks in pregnancy and puerperium is one of the most important tasks of clinical medicine. This article will review historical understanding of thrombosis in pregnant women, progress in understanding VTE risk factors in pregnant women, and available reserves in identifying new risk factors during pregnancy and puerperium in order to stratify risks more efficiently.

Outcomes of Multidetector Computed Tomography Pulmonary Angiography in Pregnant and Postpartum Women With Suspected Pulmonary Embolism

PURPOSE

Verify whether there is a difference in likelihood of developing pulmonary embolism (PE) between pregnant women, nonpregnant women of reproductive age, and postpartum (up to 6 weeks) women, by comparing their outcomes on computed tomography pulmonary angiography (CTPA) done for suspicion of PE.

MATERIALS AND METHODS

Retrospective cohort study of 1463 CTPA done for suspicion of PE in females of reproductive age (18-40 years), nonpregnant, pregnant (antepartum), and postpartum, from 2 tertiary-care academic hospitals between October 2006 and September 2015. Primary outcome was diagnosis of PE on imaging. Additional assessment was made of technical adequacy of the studies and method of delivery for the postpartum cohort (vaginal vs caesarean birth). Twenty-nine technically nondiagnostic studies were excluded. The effect of any potential variable on PE status was tested using univariate logistic regression. Subgroup analysis was performed after excluding patients with independent risk factors for PE.

RESULTS

The rate of CTPA positive for PE was less among pregnant patients compared to early postpartum and nonpregnant women of similar age, 2.9% vs 11.5% and 10.3%, respectively. Pregnancy was associated with statistically significant decreased odds ratio of developing a PE on CTPA, 0.23 (0.09-0.89), P value = .004. After excluding patients with additional independent risk factors for PE, there was no statistically significant odds ratio association between presence of PE on CTPA and pregnancy 0.41 (0.13-1.34), P value = .14.

CONCLUSION

Rate of CTPA positive for PE in pregnant women was lower than in nonpregnant and early postpartum women. Pregnancy was statistically significantly less likely to be associated with positive PE on a CTPA study. The common perception that pregnancy (antepartum state) is associated with an increased risk of PE may require a thorough critical reappraisal.

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.

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.

Antithrombin concentrate during pregnancy in congenital antithrombin deficiency: a single-center experience

: Pregnancy carries a high risk of thromboembolic complications, especially in the postpartum period. This risk is particularly high in women with inherited thrombophilias, among these antithrombin deficiency seems to carry the highest risk. In this case, the use of low molecular weight heparin (LMWH) is recommended, while the use of antithrombin concentrate is controversial. We report our experience of seven pregnancies occurred in five women: two, with a personal and familiar history negative for venous thromboembolism, were treated with LMWH during pregnancy and antithrombin concentrate immediately before and after the delivery. The other three women had a personal and familiar history positive for venous thromboembolism and were treated with LMWH and antithrombin concentrate during all the pregnancy and the postpartum period. No thromboembolic or hemorrhagic complications were observed in both groups, demonstrating that our strategy could be safe and effective.

Venous thromboembolism as a cause of severe maternal morbidity and mortality in the United States

In the U.S., deaths due to pulmonary embolism (PE) account for 9.2% of all pregnancy-related deaths or approximately 1.5 deaths per 100,000 live births. Maternal deaths and maternal morbidity due to PE are more common among women who deliver by cesarean section. In the past decade, the clinical community has increasingly adopted venous thromboembolism (VTE) guidelines and thromboprophylaxis recommendations for pregnant women. Although deep vein thrombosis rates have decreased during this time-period, PE rates have remained relatively unchanged in pregnancy hospitalizations and as a cause of maternal mortality. Changes in the health profile of women who become pregnant, particularly due to maternal age and co-morbidities, needs more attention to better understand the impact of VTE risk during pregnancy and the postpartum period.

Minimally invasive spinal anesthesia for cesarean section in maternal anticoagulation therapy: a randomized controlled trial

BACKGROUND

Anticoagulant therapy during pregnancy is widely used due to the increasing awareness of maternal hypercoagulability. Few studies have reported the use of minimally invasive spinal anesthesia in these parturients. The objective of this study was to evaluate the safety and feasibility of minimally invasive spinal anesthesia in parturients with anticoagulation therapy undergoing cesarean section.

METHODS

This was a randomized, controlled study conducted in 239 parturients using anticoagulants and undergoing selective cesarean section. 37 parturients withdrew, and finally parturients received spinal anesthesia using 27gauge pen type fine spinal needles (experimental group, n = 110) and 22gauge traditional spinal needles (control group, n = 92). The primary efficacy outcomes included low back pain (LBP) and postdural puncture headache (PDPH) after delivery. Secondary efficacy outcomes included visual analogue scale during subarachnoid puncture (VASdural), difference between visual analogue scale (VAS) during peripheral venipuncture and VASdural (∆VAS), VAS of back puncture point 24, 48 and 72 h after operation (VASdural-24 h, VASdural-48 h and VASdural-72 h, respectively), maternal satisfaction and hospitalization stay.

RESULTS

No parturient had PDPH and was suspected with spinal or intracranial haematoma in two groups. There was no significant difference in VASlbp-24 h, VASlbp-48 h and VASlbp-72 h (P = 0.056; P = 0.813; P = 0.189, respectively) between two groups. In experimental group, VASdural (P = 0.017), ∆VAS (P = 0.001) and VASdural-24 h (P < 0.0001) were lower, whereas maternal satisfaction was higher (P = 0.046). There was no significant difference in VASdural-48 h, VASdural-72 h, urination function, strength recovery and hospitalization stay (P = 0.069; P = 0.667; P = 0.105; P = 0.133; P = 0.754, respectively) between the two groups.

CONCLUSIONS

Minimally invasive spinal anesthesia provided lower VASdural, VASdrual-24 h and a higher maternal satisfaction. Hence, it is considered as a safe, reliable and reasonable option for cesarean section parturients during maternal anticoagulation therapy with normal platelet count and coagulation time.

TRIAL REGISTRATION

This study was registered at www.ClinicalTrials.gov at November 11th, 2016 ( NCT02987192 ).

Amniotic fluid as a potent activator of blood coagulation and platelet aggregation: Study with rotational thromboelastometry

INTRODUCTION

Pulmonary thromboembolism (PTE) is a leading cause of maternal death and frequently occurs during early puerperium. Amniotic fluid components are frequently observed in the maternal circulation in parturition; however, it currently remains unclear whether amniotic fluid contamination in maternal blood is related to the high incidence of PTE in early postpartum.

OBJECTIVES

To examine the influence of amniotic fluid on blood coagulation and fibrinolysis systems with thromboelastometry.

MATERIALS AND METHODS

Twenty-one pregnant women were recruited. We used whole citrated blood in ROTEM® (Tem Innovations GmbH, Munich, Germany), including the non-activated assay (NATEM), assessments for extrinsic (EXTEM) and intrinsic pathways (INTEM), fibrin polymerization (FIBTEM), and hyperfibrinolysis (APTEM), with amniotic fluid contamination, and measured the clotting time (CT), clot formation time (CFT), alpha, amplitude at 10 min (A10), maximum clot firmness (MCF), and lysis indices at 30 min (LI30) and 60 min (LI60).

RESULTS

Short CT in all assays as well as short CFT, high alpha, and increased A10 and MCF in NATEM were observed with amniotic fluid contamination. A10 and MCF as well as LI30 and LI60 decreased in EXTEM. Decreased LI60 with the mixture of amniotic fluid was not improved by tranexamic acid in APTEM.

CONCLUSIONS

Amniotic fluid accelerated thrombin production and activated platelet aggregation without inducing hyperfibrinolysis in whole blood. The activated tissue factor pathway with amniotic fluid produced soft and fragile clots due to its influence on platelets, which may be associated with, at least partly, the high incidence of PTE in early puerperium, particularly after cesarean section.

Predictive value of platelet aggregation rate in postpartum deep venous thrombosis and its possible mechanism

The present study investigated the predictive value of the platelet aggregation rate in postpartum deep venous thrombosis and its possible mechanism. From January 2014 to January 2016, 23 patients with postpartum deep vein thrombosis of lower extremity treated in the Department of Obstetrics of Beijing Chaoyang Hospital were as assigned as the observation group. At the same time, 25 cases with normal recovery were assigned as the control group. Blood samples were collected from all the subjects. The platelet aggregation rate was measured using a platelet aggregation apparatus. Plasma platelet activating factor (PAF) levels were measured by ELISA. The positive rate of platelet P-selectin (CD62p) and lysosomal membrane glycoprotein (CD63) was measured by flow cytometry. PI3K expression and AKt phosphorylation levels were measured by western blot analysis. The ROC curve was used to evaluate the value of the platelet aggregation rate in predicting postpartum deep vein thrombosis of lower extremity. The correlation between the platelet aggregation rate and PAF and PI3K/AKt expression was also analyzed. The cesarean section rate, platelet 5-min maximum aggregation rate, PAF level and the positive rate of CD62p and CD63 were significantly higher in the control than those in the observation group (P<0.05). Furthermore, the platelet aggregation rate was positively correlated with the expression of PAF, CD62p and CD63 (r=0.389, 0.451, and 0.452; all P<0.05). The platelet 5-min maximum aggregation rate for predicting postpartum deep vein thrombosis of lower extremity was reflected by the area under the ROC curve (AUC=0.797, P=0.000). The PI3Kp110β/β-actin and p-AKt/AKt ratio was significantly higher in the observation compared with the control group (P<0.05). In addition, the platelet aggregation rate was positively correlated with the expression of PI3K and phosphorylation level of AKt (r=0.441, 0.430; all P<0.05). The results suggested that platelet aggregation activity is elevated in postpartum deep vein thrombosis patients. It has a certain predictive value for the occurrence of postpartum deep vein thrombosis of lower extremity. Thuss, the PI3K/AKt signaling pathway may be one of the mechanisms of platelet aggregation.

The laboratory control of anticoagulant thromboprophylaxis during the early postpartum period after cesarean delivery

INTRODUCTION

The incidence of venous thromboembolism (VTE) after cesarean section is up to 0.6%, and the widespread use of cesarean section draws attention to this group. The dosage and duration of low-molecular-weight heparin (LMWH) prophylaxis after delivery is estimated by anamnestic risk-scales; however, the predictive potency for an individual patient's risk can be low. Laboratory hemostasis assays are expected to solve this problem. The aim of this study was to estimate the potency of tests to reflect the coagulation state of patients receiving LMWH in the early postpartum period.

MATERIALS AND METHODS

We conducted an observational study on 97 women undergoing cesarean section. Standard coagulation tests (Fg, APTT, prothrombin, D-dimer), an anti-Xa assay, rotation thromboelastometry and thrombodynamics/thrombodynamics-4D were performed. Coagulation assay parameters were compared in groups formed in the presence or absence of LMWH to estimate the laboratory assays' sensitivity to anticoagulation.

RESULTS

Coagulation assays revealed hypercoagulation after delivery and a tendency toward normalization of coagulation during early postpartum. The thromboprophylaxis results revealed a higher percentage of coagulation parameters within the normal range in the LMWH group.

CONCLUSION

This research is potentially beneficial for the application of thrombodynamics and thrombodynamics-4D in monitoring coagulation among patients with high VTE risk who receive thromboprophylaxis with heparin.

Treatment Outcomes of Anticoagulant Therapy and Temporary Inferior Vena Cava Filter Implantation for Pregnancy Complicated by Venous Thrombosis

Objective: Although deep vein thrombosis (DVT) followed by pulmonary thromboembolism (PE) is a critical complication during pregnancy, there have been few reports about its intrapartum management. We evaluated intrapartum management by using a temporary inferior vena cava filter (IVCF) in pregnant women with PE/DVT.

Materials and Methods: Eleven women with PE/DVT during pregnancy between January 2004 and December 2016 were included. The patients were hospitalized for intravenous unfractionated heparin infusion after acute PE/DVT onset. Seven patients were discharged and continued treatment with subcutaneous injection of heparin at the outpatient unit. IVCF was implanted 1–3 days before delivery in 10 patients. Anticoagulant therapy was discontinued 6–12 h before delivery. We retrospectively analyzed rates of maternal or perinatal death, and recurrence of symptomatic PE/DVT.

Results: One patient was diagnosed as having PE/DVT and 10 had DVT alone. One patient suffered hemorrhagic shock during delivery; however, maternal or perinatal death and recurrence of symptomatic PE/DVT did not occur in any patient.

Conclusion: Maternal or perinatal death and recurrence of symptomatic PE/DVT was not seen in women diagnosed as having PE/DVT during pregnancy and treated with anticoagulant therapy and IVCF.

Occult Iliac Deep Vein Thrombosis in Second Trimester Pregnancy: Clues on Bedside Ultrasound

Isolated pelvic deep vein thromboses (DVT) are rare and difficult to diagnose, but they are more common in pregnant women and carry an increased risk of embolization. Pulmonary embolism is the most common non-obstetric cause of death in pregnancy. Compression ultrasound is the first-line imaging test for suspected lower extremity DVT, but it cannot usually aid in directly visualizing or easily diagnosing isolated pelvic DVT. Nonetheless, point-of-care ultrasound (POCUS) may provide valuable clues to help rule in pelvic DVT and expedite initiation of anticoagulant therapy. Such findings include increased venous diameter, increased resistance to compression, visible venous reflux, and blunted phasicity. This case presents an example of how these findings on POCUS led the emergency physician to make the difficult diagnosis of pelvic DVT at the bedside within seconds.

Is plasminogen activator inhibitor-1 a physiological bottleneck bridging major depressive disorder and cardiovascular disease?

Major depressive disorder (MDD) is estimated to affect one in twenty people worldwide. MDD is highly comorbid with cardiovascular disease (CVD), itself one of the single largest causes of mortality worldwide. A number of pathological changes observed in MDD are believed to contribute to the development of cardiovascular disease, although no single mechanism has been identified. There are also no biological markers capable of predicting the future risk of developing heart disease in depressed individuals. Plasminogen activator inhibitor-1 (PAI-1) is a prothrombotic plasma protein secreted by endothelial tissue and has long been implicated in CVD. An expanding body of literature has recently implicated it in the pathogenesis of major depressive disorder as well. In this study, we review candidate pathways implicating MDD in CVD and consider how PAI-1 might act as a mediator by which MDD induces CVD development: chiefly through sleep disruption, adiposity, brain-derived neurotrophic factor (BDNF) metabolism, systemic inflammation and hypothalamic-pituitary-adrenal (HPA)-axis dysregulation. As both MDD and CVD are more prevalent in women than in men, and incidence of either condition is dramatically increased during reproductive milestones, we also explore hormonal and sex-specific associations between MDD, PAI-1 and CVD. Of special interest is the role PAI-1 plays in perinatal depression and in cardiovascular complications of pregnancy. Finally, we propose a theoretical model whereby PAI-1 might serve as a useful biomarker for CVD risk in those with depression, and as a potential target for future treatments.

Pregnancy-associated adaptations in [Ca2+]i-dependent and Ca2+ sensitization mechanisms of venous contraction: implications in pregnancy-related venous disorders

Pregnancy is associated with significant adaptations in the maternal hemodynamics and arterial circulation, but the changes in the venous mechanisms during pregnancy are less clear. We hypothesized that pregnancy is associated with alterations in venous function, intracellular free Ca(2+) concentration ([Ca(2+)]i), and Ca(2+)-dependent mechanisms of venous contraction. Circular segments of inferior vena cava (IVC) from virgin and late pregnant (Preg, day 19) Sprague-Dawley rats were suspended between two hooks, labeled with fura-2, and placed in a cuvet inside a spectrofluorometer for simultaneous measurement of contraction and [Ca(2+)]i (fura-2 340/380 ratio). KCl (96 mM), which stimulates Ca(2+) influx, caused less contraction (35.6 ± 6.3 vs. 92.6 ± 19.9 mg/mg tissue) and smaller increases in [Ca(2+)]i (1.67 ± 0.12 vs. 2.19 ± 0.11) in Preg vs. virgin rat IVC. The α-adrenergic receptor agonist phenylephrine (Phe; 10(-5) M) caused less contraction (23.8 ± 3.4 vs. 70.9 ± 12.9 mg/mg tissue) and comparable increases in [Ca(2+)]i (1.76 ± 0.10 vs. 1.89 ± 0.08) in Preg vs. virgin rat IVC. At increasing extracellular Ca(2+) concentrations ([Ca(2+)]e) (0.1, 0.3, 0.6, 1, and 2.5 mM), KCl and Phe induced [Ca(2+)]e-contraction and [Ca(2+)]e-[Ca(2+)]i curves that were reduced in Preg vs. virgin IVC, supporting reduced Ca(2+) entry mechanisms. The [Ca(2+)]e-contraction and [Ca(2+)]e-[Ca(2+)]i curves were used to construct the [Ca(2+)]i-contraction relationship. Despite reduced contraction and [Ca(2+)]i in Preg IVC, the Phe-induced [Ca(2+)]i-contraction relationship was greater than that of KCl and was enhanced in Preg vs. virgin IVC, suggesting parallel activation of Ca(2+)-sensitization pathways. The Ca(2+) channel blocker diltiazem, protein kinase C (PKC) inhibitor GF-109203X, and Rho-kinase (ROCK) inhibitor Y27632 inhibited KCl- and Phe-induced contraction and abolished the shift in the Phe [Ca(2+)]i-contraction relationship in Preg IVC, suggesting an interplay between the decrease in Ca(2+) influx and possible compensatory activation of PKC- and ROCK-mediated Ca(2+)-sensitization pathways. The reduced [Ca(2+)]i and [Ca(2+)]i-dependent contraction in Preg rat IVC, despite the parallel rescue activation of Ca(2+)-sensitization pathways, suggests that the observed reduction in [Ca(2+)]i-dependent contraction mechanisms is likely underestimated, and that the veins without the rescue Ca(2+)-sensitization pathways could be even more prone to dilation during pregnancy. These pregnancy-associated reductions in Ca(2+) entry-dependent mechanisms of venous contraction, if occurring in human lower extremity veins and if not adequately compensated by Ca(2+)-sensitization pathways, may play a role in pregnancy-related venous disorders.

Reference Intervals of Routine Coagulation Assays During the Pregnancy and Puerperium Period

BACKGROUND

Significant changes occur in the coagulation and fibrinolytic systems during pregnancy and puerperium in the plasma levels. However, reference ranges based on healthy people are not optimal for informing clinical decisions during the pregnancy and puerperium. Therefore, it is essential to explore coagulation assays' reference ranges during the pregnancy and puerperium.

METHODS

Prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (Fib.), and D-dimer were all measured according to the manufacturer's specifications and laboratory standard operating procedure of the STA-R evolution coagulation analyzer. A total of 11,601 women were enrolled in this study.

RESULTS

The reference ranges for PT, APTT, TT, Fib., and D-dimer in nonpregnancy period were 10.87-13.76 s, 29.22-44.61 s, 15.39-20.15 s, 1.59-3.97 g/l, and 0-0.56 mg/l, respectively. In early-pregnancy period, the ranges were 11.14-14.07 s, 29.97-44.69 s, 14.92-19.03 s, 1.98-4.13 g/l, and 0-1.67 mg/l, respectively. In midpregnancy period, the ranges were 9.98-12.84 s, 28.53-40.70 s, 13.51-19.82 s, 2.63-5.19 g/l, and 0-2.81 mg/l, respectively. In late-pregnancy period, the ranges were 9.48-12.58 s, 28.61-40.80 s, 14.10-19.61 s, 2.80-5.56 g/l, and 0-27.08 mg/l, respectively. In puerperium period, the ranges were 10.85-13.72 s, 30.51-43.02 s, 15.31-19.64 s, 1.14-5.07 g/l, and 1.27-4.85 mg/l, respectively.

CONCLUSION

We presented reference intervals for coagulation assays from the nonpregnancy to puerperium period that can be adopted in other laboratories after further validation.