D-dimer levels during delivery and the postpartum

Diagnostic strategies in postpartum individuals with suspected venous thromboembolism: A scoping review

BACKGROUND

The risk of venous thromboembolism (VTE) is increased postpartum and contributes to important morbidity and mortality. While there have been advances in evaluating diagnostic algorithms for suspected VTE during pregnancy, there is limited data for postpartum individuals.

OBJECTIVE

We conducted a scoping review to describe and evaluate diagnostic strategies used to investigate suspected VTE in postpartum individuals.

METHODS

A comprehensive search strategy was conducted in Ovid MEDLINE, Embase and the Cochrane Central Register of Controlled Trials (January 1, 2000-September 30, 2022) to identify original articles that reported on diagnostic strategies in postpartum individuals with suspected VTE. We extracted demographics, clinical decision rules used, D-dimer and imaging completed, including test performance and VTE outcomes.

RESULTS

A total of 13 studies conducted across 11 countries with separate postpartum data were included for 759 individuals with suspected PE (n = 634) or DVT (n = 125), including unpublished data (n = 251). Among those with suspected PE, computed tomography pulmonary angiography was conducted more commonly (n = 522) than ventilation-perfusion scans (n = 69), with PE positivity rates that ranged from 4 %-27.6 % and 0-50 % across studies, respectively. Among 131 postpartum individuals with suspected PE who had a D-dimer measured, only 4.6 % (6/131) had a negative D-dimer test. For postpartum individuals with suspected DVT, the most common diagnostic test was compression ultrasonography (positivity rate 12.2 %-18.6 %). There were limited retrospective data evaluating the clinical decision rules.

CONCLUSIONS

There are heterogeneous approaches globally in the diagnosis of suspected postpartum VTE. Limited high-quality data available underscores the need for more robust evidence to inform clinical practice.

Comparison of Maternal and Neonatal Outcomes between SARS-CoV-2 Variants: A Retrospective, Monocentric Study

The impact of SARS-CoV-2 variants on maternal and neonatal outcomes during pregnancy is still poorly understood, and the emergence of different variants has further complicated our understanding of the virus's effects. This retrospective, monocentric study aimed to fill this knowledge gap by analyzing the outcomes of pregnant women with acute SARS-CoV-2 infection caused by the Alpha, Delta, and Omicron variants. The study, conducted between December 2020 and March 2022 at San Marco Hospital, included 313 pregnant women with confirmed SARS-CoV-2 infection. The results showed that the Delta variant was associated with a significantly higher incidence of adverse outcomes, such as premature births, maternal intensive care unit admission, intrauterine growth restriction, and small for gestational age infants. Additionally, the Delta variant was linked to lower Apgar scores, higher maternal and fetal mortality rates, and increased levels of various biomarkers indicating more severe illness. Finally, the Delta variant also presented a greater possibility of vertical transmission. These findings underscore the complexity of understanding the impact of SARS-CoV-2 on pregnancy outcomes, especially considering the distinctive characteristics of different variants. By better understanding the specific impacts of each variant, appropriate preventive measures and management strategies can be implemented to optimize maternal and neonatal outcomes.

Laboratory Testing of Hemostasis in Pregnancy: A Brief Overview

Normal pregnancy is associated with significant physiological changes in the coagulation and fibrinolytic systems with an inclination toward a hypercoagulable state. This includes an increase in plasma levels of most clotting factors, a decrease in endogenous anticoagulants, and inhibition of fibrinolysis. Although these changes are critical in maintaining placental function and reducing postpartum hemorrhage, they may contribute to an increased risk of thromboembolism, particularly toward the end of pregnancy and during puerperium. Hemostasis parameters and the non-pregnant population reference ranges cannot be used in the assessment of bleeding or thrombotic complication risk during pregnancy, and pregnancy-specific information and reference ranges are not always available to support the interpretation of laboratory tests. This review aims to summarize the use of relevant hemostasis tests to promote evidence-based interpretation of laboratory test results as well as discuss challenges associated with testing during pregnancy.

Potential critical risks of pulmonary thromboembolism from an asymptomatic postpartum ovarian vein thrombosis: a case report

Background

Ovarian vein thrombosis (OVT) may cause maternal mortality by inducing pulmonary thromboembolism (PTE). However, the prevalence, etiology, risk factors, prognosis, and optimal treatments for asymptomatic OVT during and after pregnancies are unclear, which therefore requires a high clinical index of suspicion for certain diagnoses due to its vague presentation. We herein present a case of asymptomatic postpartum OVT that extended toward the inferior vena cava (IVC), resulting in a potential risk of PTE.

Case presentation

A 30-year-old postpartum woman presented with slight dyspnea after an uneventful vaginal delivery at 40 weeks of gestation. We checked her laboratory data to exclude lethal thrombosis; D-dimer levels were 85.6 μg/mL. We performed computed tomography (CT) to search the presence of PTE and deep vein thrombosis (DVT); although no signs of PTE and DVT in her legs were detected, CT and trans-abdominal ultrasonography (TAUS) revealed a right OVT. Heparin was administered, and D-dimer levels decreased; warfarin at a dose of 2 mg/day was subsequently administered to control anti-coagulopathy. However, D-dimer was re-elevated despite adequate anticoagulation treatment, and extension of the right OVT to the IVC was detected by CT and TAUS. With warfarin administration, CT and TAUS showed the disappearance of right OVT. The patient was discharged from the hospital 17 days after delivery.

Conclusions

Even asymptomatic postpartum OVT may lead to PTE. Universal screening guidelines and optimal treatment strategies for asymptomatic OVT in pregnant and postpartum women should be established through future studies.

Prevention of venous thromboembolism in pregnant women with congenital antithrombin deficiency: a retrospective study of a candidate protocol

BACKGROUND

The best thromboprophylaxis for pregnant women with congenital antithrombin deficiency (CAD) is controversial.

OBJECTIVE

To clarify the effectiveness of a protocol for venous thromboembolism (VTE) prevention in pregnant women with CAD.

METHODS

Women at high risk of VTE were administered antithrombin concentrate and heparin after conception, whereas those at low risk of VTE were administered heparin alone until delivery. All women received antithrombin concentrate at delivery except for one who was diagnosed with CAD.

RESULTS

Ten women had CAD, including one in the high-risk group and nine in the low-risk group. No women had VTE at delivery as per the protocol for VTE prevention. Almost all women had increased antithrombin activity before delivery followed by maintenance at ≥ 70% due to antithrombin concentrate administration. VTE prophylaxis during and after delivery was successful in all women with CAD. However, one woman in the low-risk group did not receive heparin and developed VTE induced by severe hyperemesis at 9 gestational weeks, before the diagnosis of CAD. Women in the high-risk group received antithrombin concentrate after delivery but had increased D-dimer levels at postpartum.

CONCLUSIONS

Our protocol to prevent VTE in pregnant women with CAD is safe and effective.

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.

D-dimer level significance for deep vein thrombosis screening in the third trimester: a retrospective study

Background

Venous thromboembolism often develops after surgery and childbirth, resulting in death in some cases. Although early deep vein thrombosis (DVT) detection can predict pulmonary thromboembolism, there is no early screening method for DVT in pregnant women. Lack of consensus regarding significance or setting and cut-off value interpretation of D-dimer levels further impedes venous thromboembolism screening in pregnant women.

This study aimed to examine the utility of third-trimester serum D-dimer levels as a screening test for DVT during pregnancy and to determine the frequency of asymptomatic DVT using lower-limb compression ultrasonography.

Methods

This single-center retrospective study included 497 pregnant women who underwent elective cesarean section at term in our hospital between January 2013 and December 2019. Serum D-dimer levels were preoperatively measured at 32–37 weeks’ gestation. The presence or absence of DVT in patients with serum D-dimer levels ≥ 3.0 µg/ml, the cut-off value, was examined using compression ultrasonography. In all patients, the presence or absence of clinical venous thrombosis (symptoms such as lower-limb pain, swelling, and heat sensation) was examined within 4 postoperative weeks.

The Royal College of Obstetricians and Gynecologists Guideline 2015 was referred to determine risk factors for the onset of venous thrombosis during pregnancy. Among those, we examined the risk factors for DVT that result in high D-dimer levels during pregnancy.

Results

The median age and body mass index were 35 (20–47) years and 21.2 (16.4–41.1) kg/m², respectively. Further, the median gestational age and D-dimer levels were 37 weeks and 2.1 (0.2–16.0) µg/ml, respectively. Compression ultrasonography was performed on 135 (26.5%) patients with a D-dimer level ≥ 3.0 µg/ml, with none of the patients showing DVT. All patients were followed up for 4 postoperative weeks, with none presenting with venous thromboembolism. Multivariate analysis showed that hypertensive disorders of pregnancy are an independent risk factor for venous thromboembolism that causes high D-dimer levels (odds ratio: 2.48, 95% confidence interval: 1.05–6.50, P = 0.04).

Conclusion

There may be low utility in screening for DVT using D-dimer levels in the third trimester. Further, prepartum asymptomatic DVT has a low frequency, indicating the low utility of compression ultrasonography.

Trial registration

Institutional Review Board of Tottori University Hospital (IRB no. 20A149).

Indicators of the Condition of Newborn Calves after Difficult Labor Syndrome

Difficult Labor Syndrome is recorded in 37.9 % of newborn calves. Newborn calves assessed on the Apgar scale of 2 points, are assigned to the cluster class born after easy labor, 1 point – after moderate labor and 0 points for difficult labor. The characteristic features of newborn calves after light birth are the manifestation of statistical functions and free movement. In newborn calves born with moderate and severe labor severity, weakly expressed motor-food reflexes are manifested. Visible mucous membranes are pale in color. Breathing is slow and shallow. Heart sounds are weak, the pulse is arrhythmic, slowed down with a decrease in the pulse wave. Decrease in glucose concentration, increase in total bilirubin level by 1.9 times with moderate severity of labor and 2.5 times with severe course of labor. An excess of creatinine contributes to the liborilization of the function of eosinophils, as a result, a symptom develops due to sensitization of the body. The activity of gamma-lutamyl transpeptidase in newborn calves after the Difficult Labor Syndrome in one hour increases 18.6 times, the activity of alkaline phosphatase during this period increases 1.5 times, aspartate aminotransferase and alanine aminotransferase - 1.6 times, lactate dehydrotransferase - 1.3 times. The most significant increase in the first 24 hours is the activity of γ-glutamyl transferase. At the age of one day, it exceeds the initial one by 95.6 times. The studies carried out indicate that the concentration of double bonds in the blood of newborn calves after the Difficult Labor Syndrome is marked by an increase of 20.46 % with an average severity of labor and 34.13 % with a severe course of labor when compared with a mild severity of labor. The level of diene conjugates in the blood of newborn calves with mild labor severity in comparison with moderate labor severity was statistically significantly increased (p <0.05), and 1.87 times with severe labor (p <0.01). The concentration of intermediate products of ketodienes and conjugated trienes in the blood of newborn calves with mild labor severity was statistically significantly increased by 1.75 times compared with moderate labor severity and 3.54 times with severe labor (p <0.01). Reduced glutathione is among the considered indicators of the least sensitivity (26.0 %) and specificity (43.0 %) in newborn calves after the Difficult Labor Syndrome.

Postpartum ovarian vein thrombosis manifesting as acute appendicitis: a case report

BACKGROUND

Postpartum ovarian thrombosis is an uncommon condition. It appears with the nonspecific, predominantly right-sided abdominal symptoms and must be differentiated from other acute visceral conditions. If left untreated, postpartum ovarian thrombosis can have severe consequences, including sepsis, pulmonary embolism, and even death. Momentarily, there are no specific guidelines for postpartum ovarian thrombosis management. We present a case of postpartum ovarian thrombosis admitted to our hospital with symptoms of acute appendicitis. CASE PRESENTATION : A 39-year-old Omani obese multiparous woman of Afro-Arab origin was admitted with acute symptoms, mainly abdominal pain, fever, and vomiting 1 week postpartum. Clinical picture and biochemical profile did not exhibit a recognizable pattern. Ultrasonography excluded retained products of conception. Computerized scan for abdomen and pelvis with oral and intravenous contrast reported a dilated tubular structure in the right adnexa extending up to the right renal hilum level with surrounding inflammation. Those findings were consistent with the thrombophlebitis of the right ovarian vein. Blood cultures and sensitivity showed group A β-hemolytic streptococci sensitive to penicillin G and clindamycin. The patient was treated successfully with antibiotics and therapeutic anticoagulants and discharged home 3 days later; follow-up was arranged.

CONCLUSION

This pathology is an exceptional entity in Oman. Therefore, awareness of this unique condition is required so that clinicians will be vigilant, exploring similar cases with imaging and avoiding unnecessary surgical interventions.

Maternal thrombin generation and D-dimer levels in obesity and pregnancy: results from the maternal thrombin generation in obesity and pregnancy (MaTOPs) study

Venous thromboembolic disease (VTE) risk increases five-fold antenatally and 14-fold during the puerperium. Obesity significantly increases this risk. The D-dimer assay and more novel Calibrated Automated Thrombogram (CAT) assay laboratory tests display potential for use in VTE risk stratification in pregnancy, although to date, research in the performance characteristics of these tests in obese and nonobese pregnant populations is limited. The aim of this study was to compare D-dimer and thrombin generation levels in obese and nonobese pregnant women. Pregnant women were recruited and categorised, as obese (BMI ≥30) or nonobese (BMI 18.5-25). Blood was collected at 26-28 weeks' gestation, 36-40 weeks' gestation and 6-12 weeks postpartum and D-dimer concentrations and endogenous thrombin potential (ETP) were determined. Student's t-test was used to analyse differences in mean D-dimer and ETP. At 36-40 weeks, obese pregnant women had higher D-dimer concentrations (P = 0.001) but lower ETP levels compared with nonobese women (P = 0.044). D-dimer was higher in nonobese than in obese women at 6-12 weeks postpartum (P = 0.026). There was no difference in mean D-dimer (P  = 0.825) and mean ETP (P  = 0.424) between obese and nonobese women at 26-28 weeks. No difference was observed in mean ETP at 6-12 weeks postpartum (P  = 0.472). ETP was lower in both obese and nonobese women postpartum than during pregnancy. D-dimer was lower in obese women but not in nonobese women postpartum. D-dimer concentrations and ETP were not significantly different during multiple time points in pregnancy and postpartum between obese and nonobese pregnant women suggesting limited utility in VTE risk assessment in obese pregnant women.

Thrombolysis in massive and submassive pulmonary embolism during pregnancy and the puerperium: a systematic review

Thrombolysis in high-risk pulmonary embolism (PE) patients is recommended worldwide; however, the evidence for thrombolysis during pregnancy and the immediate puerperium remains unclear. We conducted a systematic review from 1950 to 2019 through PubMed, Ovid/Willey, and Cochrane Library to assess the safety and effectiveness of thrombolysis during pregnancy and the immediate puerperium. Additionally, we characterized the clinical presentation, risk stratification, and diagnostic approach. We have communicated our results according to the PRISMA statement. We collected 141 records and, after critical assessment, included 47 case reports of 54 patients, including 43 and 11 patients during pregnancy and puerperium, respectively. During pregnancy, alteplase was the most frequent systemic thrombolytic agent used (67%), but only nine patients received the approved FDA regimen. With catheter-directed thrombolysis, low-dose thrombolytics and fragmentation were the most common regimens. Major bleeding occurred in 18% of cases, but there was no intracranial bleeding. One maternal death occurred secondary to refractory cardiogenic shock. Fetal mortality was 20%. During the immediate puerperium, nine patients received "off-label" first-, second-, and third-generation thrombolytic regimens, and four cases underwent catheter-directed thrombolysis. We observed nine major bleeding events, seven of which were from the uterine location and none of which were intracranial. In conclusion, overall, these data do not suggest prohibitive risk associated with thrombolysis for PE in pregnancy. Management of massive and high-risk submassive PE in pregnancy should be individualized to each patient. In the data presented, no fatal bleeding or intracranial bleeding was observed. Finally, future efforts should systematically collect and report data on high-risk PE in pregnancy and peripartum patients to improve the evidence-base clinical practice.

Maternal and perinatal outcomes and placental pathologic examination of 29 SARS-CoV-2 infected patients in the third trimester of gestation

AIM

On December 31, 2019, an unknown outbreak of pulmonary disease was reported in China. The novel coronavirus SARS-CoV-2 was the etiologic agent of this disease, and responsible of the current pandemic of COVID-19. Accumulated evidence on placental features is based most on case-reports and small case-series, with differing results.

METHODS

We gathered a cohort of 29 infected pregnant mothers who delivered 32 newborns, and had placentas available for pathologic examination. Placentas were compared with a control group.

RESULTS

Of the 29 mothers, clinical and radiological features were similar to what was already described in COVID-19. Pregnancy modified some analytical parameters. One of the mothers succumbed to the disease. Of the 32 newborns, 1 developed an early infection, with positive reverse-transcriptase polymerase chain reaction (RT-PCR) at 48 h of life, with an initial RT-PCR negative. SARS-CoV-2 presence was assessed on placental tissue with immunohistochemistry and RT-PCR, both were negative. All newborns had good clinical outcomes. No differences in morphological placental findings were found among both groups.

CONCLUSION

Lack of statistically significant differences among case and control groups suggest that placentas from SARS-CoV-2 infected mothers represent a cohort of normal placentas only submitted because of maternal SARS-CoV-2 status. To the best of our knowledge, no irrefutable cases of vertical transmission have been yet described. Other authors have failed to demonstrate presence of viral RNA in placental tissue. Accumulated knowledge suggests that if vertical transmission is possible, it is a rare event.

Risk factors for pregnancy-associated venous thromboembolism in Singapore

OBJECTIVES

Pregnancy-associated venous thromboembolism (VTE), including deep venous thrombosis (DVT) and pulmonary embolism (PE), is associated with increased risk of maternal mortality and morbidity. This study aimed to assess potential risk factors for pregnancy-associated VTE.

METHODS

In this case-control study, women with pregnancy-associated VTE were identified via International Classification of Diseases codes and included if they had been objectively diagnosed with VTE during pregnancy or within six weeks postpartum, from 2004 to 2016, at KK Women's and Children's Hospital or Singapore General Hospital in Singapore. Controls, i.e. pregnant women without VTE, were selected from a prospective longitudinal study. The odds ratio (OR) for VTE was computed for a range of maternal and obstetric factors.

RESULTS AND CONCLUSIONS

From 2004 to 2016, 89 cases of pregnancy-associated VTE and 926 controls were identifed and analysed using logistic regression. The most significant risk factors for pregnancy-associated VTE were smoking (OR 5.44, p=0.0002) and preterm delivery (OR 5.06, p=0.023). Malay race, multiparity, non-O blood group and caesarean section, were also identified to be of higher risk. These risk factors should be useful in the development of thromboprophylaxis strategies for pregnancy and the postpartum period, especially in Singapore.

Assessing maternal clotting function with novel global coagulation assays: A prospective pilot study

INTRODUCTION

Women are at higher risk of venous thromboembolism (VTE) during pregnancy and the puerperium. Global coagulation assays (GCAs), including thromboelastography (TEG), thrombin generation using the calibrated automated thrombogram (CAT) and fibrin generation using the overall haemostatic potential assay (OHP), provide a more comprehensive assessment of the coagulation process than conventional coagulation assays. We aimed to evaluate the ability of these GCAs to analyse the coagulability among pregnant women of varying VTE risk profile.

METHODS

Women undergoing term elective caesarean delivery provided a single predelivery blood sample for conventional and novel coagulation testing (TEG, CAT and OHP). Data from 47 healthy nonpregnant women aged 18-45 years were used as controls.

RESULTS

Sixty women with term singleton pregnancies were included. Samples from pregnant women were hypercoagulable on most GCA parameters compared to nonpregnant controls, demonstrating increased maximum amplitude (clot strength) (71.5 vs 60.6 mm, P < .001) on whole blood TEG and increased endogenous thrombin potential (1895.22 vs 1399.33 nmol/L·min, P < .001) and overall coagulation potential (fibrin generation) (57.58 vs 36.21 units, P < .001) on platelet-poor plasma. Pregnant women with booking BMI ≥ 30 kg/m² had significantly higher maximum amplitude compared to pregnant women of normal BMI (18.5-25 kg/m² ) (73.2 vs 66.1 mm, P < .001).

CONCLUSIONS

Global coagulation assays reliably detect the physiological hypercoagulability of pregnancy. Thromboelastography in particular appears to correlate with obesity in the pregnant population. GCAs may be potential adjuncts to risk factor-based criteria to guide VTE thromboprophylaxis during pregnancy and the puerperium.

Changes in serum D-dimer level and effect of enoxaparin sodium after a cesarean section: a retrospective study

Background: Pregnancy increases the risk of venous thromboembolism (VTE). During pregnancy and a post-cesarean section, an increase in D-dimer levels can be observed. However, to date, the usefulness of the D-dimer level measurement for thrombosis in pregnant women has not been determined.Objects: We aimed to evaluate the changes in D-dimer levels after a cesarean section, the risk factors of high D-dimer levels, and enoxaparin sodium's preventive effects on VTE.Methods: This retrospective study enrolled 160 pregnant women who underwent a cesarean section. D-dimer levels were measured on postoperative day (POD)1 and POD6. If on POD1, the D-dimer levels were ≥10 µg/mL, enoxaparin sodium was administered until POD7. Regardless of enoxaparin administration, when the D-dimer levels on POD6 were ≥10 µg/mL, lower-limb venous ultrasonography was performed. After a cesarean section, patients were screened for the following: factors causing high D-dimer levels, incidence of deep vein thrombosis (DVT), and need for enoxaparin.Results: The median D-dimer levels on POD1 and POD6 were 7.5 µg/mL (1.1-34.1) and 4.2 µg/mL (0.02-31.4), respectively. Enoxaparin sodium was administered to 56 patients (35%). The D-dimer levels on POD6 decreased more significantly than on POD1. The median D-dimer levels in the enoxaparin administration group significantly dropped from 14.3 (POD1) to 3.9 (POD6) (p<.001). The D-dimer levels on POD1 were higher in patients aged ≥35 years and with a hospitalization history of threatened preterm labor. In addition, on POD6, patients aged ≥35 years and with a high body mass index had high D-levels. Following a multivariate analysis, the elderly represent an independent factor for high D-levels. DVT was not observed.Conclusion: When the D-dimer levels on POD1 after a cesarean section are ≥10 µg/mL, enoxaparin reduces D-dimer levels six days after cesarean section. Moreover, patients aged ≥35 years represent an independent factor for high D-levels. These findings should be validated by further studies.

Mode of Delivery Does Not Influence Postpartum Hypercoagulability Measured by Thrombin Generation or Thromboelastometry

Introduction  Venous thromboembolism (VTE) is a significant cause of maternal mortality with the greatest risk postpartum. Mode of delivery influences VTE risk, with emergency caesarean section (CS) associated with the highest risk (CS). Thromboprophylaxis is recommended for selected women to reduce the risk of VTE.

We aimed to investigate the impact of mode of delivery and thromboprophylaxis on hypercoagulability as measured by thromboelastometry (TEM) and thrombin generation (TG) in women at high VTE risk.

Materials and Methods  Blood was collected from 99 pregnant women with VTE risk factors at up to five time points from pre- (T1) and post (T2)-delivery to 6 weeks postpartum (T5). Multiple linear regression was utilised to compare TG and TEM between those with vaginal delivery (VD) and CS at each time point. Paired sample t -test with post hoc Bonferroni correction was utilised to compare laboratory markers over time.

Results  Women in both groups had a median of three postpartum VTE risk factors, with higher body mass index and parity post-VD. In both the groups, TG and TEM parameters suggested hypercoagulability at T2 compared with T1, with resolution at T5. There were minimal differences between groups, apart from T2 with shorter clot formation time and higher maximum clot firmness in the VD group.

Conclusion  TG and TEM illustrate hypercoagulability associated with pregnancy and delivery. The pattern of postpartum hypercoagulability seen in women with VTE risk factors was similar irrespective of mode of delivery. Further research is required to establish the effect of labour on TG/TEM in the absence of low molecular weight heparin use.

Risk of venous thromboembolism in Chinese pregnant women: Hong Kong venous thromboembolism study

Background

Previous Caucasian studies have described venous thromboembolism in pregnancy; however, little is known about its incidence during pregnancy and early postpartum period in the Chinese population. We investigated the risk of venous thromboembolism in a "real-world" cohort of pregnant Chinese women with no prior history of venous thromboembolism.

Methods

In this observational study, 15,325 pregnancies were identified in 14,162 Chinese women at Queen Mary Hospital, Hong Kong between January 2004 and September 2016. Demographic data, obstetric information, and laboratory and imaging data were retrieved and reviewed.

Results

The mean age at pregnancy was 32.4±5.3 years, and the median age was 33 years (interquartile range, 29-36 yr). Pre-existing or newly diagnosed diabetes mellitus was present in 627 women (4.1%); 359 (0.7%) women had pre-existing or newly detected hypertension. There was a small number of women with pre-existing heart disease and/or rheumatic conditions. Most deliveries (86.0%) were normal vaginal; the remaining were Cesarean section 2,146 (14.0%). The incidence of venous thromboembolism was 0.4 per 1,000 pregnancies, of which 83.3% were deep vein thrombosis and 16.7% were pulmonary embolism. In contrast to previous studies, 66.7% of venous thrombosis occurred in the first trimester.

Conclusion

Chinese women had a substantially lower risk of venous thromboembolism during pregnancy and the postpartum period compared to that of Caucasians. The occurrence of pregnancy-related venous thromboembolism was largely confined to the early pregnancy period, probably related to the adoption of thromboprophylaxis, a lower rate of Cesarean section, and early mobilization.

Pregnancy and Pulmonary Embolism

Venous thromboembolism (VTE), referring to both deep vein thrombosis and pulmonary embolism, is a leading cause of death in the developed world during pregnancy. This increased risk is attributed to the Virchow triad, inherited thrombophilias, along with other standard risk factors, and continues for up to 6 to 12 weeks postpartum. During the peripartum period, women should be risk stratified and preventive measures should be initiated based on their risk. Diagnostic tests and treatment strategies commonly used in VTE differ in pregnancy. An understanding of these differences is imperative to diagnose with confidence and to treat appropriately.

Review article: Investigations and the pregnant woman in the emergency department - part 1: Laboratory investigations

Accurate assessment of the pregnant patient in the ED depends on knowledge of physiological changes in pregnancy, and how these changes may impact on pathology tests, appearance on point-of-care ultrasound and electrocardiography. In addition the emergency physician needs to be cognisant of disorders that are unique to or more common in pregnancy. Part 1 of this review addresses potential deviations in laboratory investigation reference intervals resulting from physiological alterations in pregnancy, and the important causes of abnormal laboratory results in pregnancy. Part 2 will address the role of point-of-care ultrasound in pregnancy, physiological changes that may affect interpretation of point-of-care ultrasound, physiological changes in electrocardiography, and the safety of radiological procedures in the pregnant patient.

Imaging in the post-partum period: clinical challenges, normal findings, and common imaging pitfalls

Complex physiological and biochemical changes occur in women during the post-partum period, many of which are incompletely understood. There are limited descriptions within the medical literature about expected imaging findings during this period and this review aims to illustrate 'normal' appearances following vaginal delivery and Cesarean section. We will also discuss some of the pertinent clinical challenges and imaging pitfalls encountered in assessing the post-partum female.

Effect of tranexamic acid on coagulation and fibrinolysis in women with postpartum haemorrhage (WOMAN-ETAC): protocol and statistical analysis plan for a randomized controlled trial

Background: Postpartum haemorrhage (PPH) is a leading cause of maternal death. Tranexamic acid has the potential to reduce bleeding and a large randomized controlled trial of its effect on maternal health outcomes in women with PPH (The WOMAN trial) is ongoing. We will examine the effect of tranexamic acid on fibrinolysis and coagulation in a subset of WOMAN trial participants.

Methods: Adult women with clinically diagnosed primary PPH after vaginal or caesarean delivery are eligible for inclusion in the WOMAN trial. In a sub-group of trial participants, blood samples will be collected at baseline and 30 minutes after the first dose of tranexamic acid or matching placebo.  Our primary objective is to evaluate the effect of tranexamic acid on fibrinolysis. Fibrinolysis will be assessed by measuring D-dimers and by rotational thromboelastometry (ROTEM). Secondary outcomes are international normalized ratio (INR), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, haemoglobin and platelets. We aim to include about 180 women from the University College Hospital, Ibadan in Nigeria.

Discussion:  This sub-study of WOMAN trial participants should provide information on the mechanism of action of tranexamic acid in women with postpartum haemorrhage. We present the trial protocol and statistical analysis plan. The trial protocol was registered prior to the start of patient recruitment. The statistical analysis plan was completed before un-blinding.

Trial registration: The trial was registered: ClinicalTrials.gov, Identifier NCT00872469 https://clinicaltrials.gov/ct2/show/NCT00872469; ISRCTN registry, Identifier ISRCTN76912190 http://www.isrctn.com/ISRCTN76912190 (Registration date: 22/03/2012).

How to use D-dimer in acute cardiovascular care

D-dimer testing is important to aid in the exclusion of venous thromboembolic events (VTEs), including deep venous thrombosis and pulmonary embolism, and it may be used to evaluate suspected aortic dissection. D-dimer is produced upon activation of the coagulation system with the generation and subsequent degradation of cross-linked fibrin by plasmin. Many different assays for D-dimer testing are currently used in routine care. However, these tests are neither standardized nor harmonized. Consequently, only clinically validated assays and assay specific decision limits should be used for routine testing. For the exclusion of pulmonary embolism/deep vein thrombosis, age-adjusted cut-offs are recommend. Clinicians must be aware of the validated use of their hospital's D-dimer assay to avoid inappropriate use of this biomarker in routine care.

Diagnosis of Acute Neurologic Emergencies in Pregnant and Postpartum Women

Acute neurologic symptoms in pregnant and postpartum women may be caused by exacerbation of a preexisting neurologic condition, the initial presentation of a non-pregnancy-related problem, or a new neurologic problem. Pregnant and postpartum patients with headache and neurologic symptoms are often diagnosed with preeclampsia or eclampsia; however, other etiologies must also be considered. A team approach with close communication between emergency physicians, neurologists, maternal-fetal medicine specialists, and radiologists is the key to obtaining best outcomes. This article reviews the clinical features and differential diagnosis of acute serious neurologic conditions in pregnancy and the puerperium, focusing on diagnosis.

Perinatal determinants of D-dimer levels in a cross-sectional study of low risk pregnant women

BACKGROUND

To examine perinatal determinants of the antenatal levels of D-dimers.

METHODS

Cross-sectional study of 760 low risk pregnant women recruited into five gestational groups. Variables examined in antenatal groups included maternal age, body mass index, parity, smoking, family history venous thromboembolism (VTE) and previous use of the oral contraceptive pill (OCP). Onset of labour and mode of delivery were also examined in the post-natal group.

RESULTS

D-dimer levels in group 4 (38-40 + 6) were significantly lower in the women with a history of taking the OCP when compared to those that had not taken it in the past (P = 0.027). In the day 2 post-natal group, the median level of D-dimer was significantly higher in primparous when compared to multiparous women (P = 0.015). The median D-dimer levels were significantly lower in the elective Caesarean section group in comparison to spontaneous onset (P = 0.003) and induction of labour (P = 0.016). When the mode of delivery was examined, the median D-dimer levels were significantly lower in those that had an elective Caesarean section when compared to normal vaginal delivery (P = 0.008) and instrumental vaginal delivery (P = 0.007). Women post elective Caesarean section had a significantly lower D-dimer than those after emergency Caesarean section (P = 0.008).

DISCUSSION

There are some significant differences in D-dimer levels when certain perinatal determinants are examined. This work is potentially beneficial to the future diagnosis of VTE in pregnancy as it supports previously published recommended D-dimer levels for the diagnosis of VTE in pregnancy.

Large D-Dimer Fluctuation in Normal Pregnancy: A Longitudinal Cohort Study of 4,117 Samples from 714 Healthy Danish Women

Introduction. D-dimer levels increase throughout pregnancy, hampering the usefulness of the conventional threshold for dismissing thromboembolism. This study investigates the biological fluctuation of D-dimer in normal pregnancy. Methods. A total of 801 healthy women with expected normal pregnancies were recruited. D-dimer was repeatedly measured during pregnancy, at active labor, and on the first and second postpartum days. Percentiles for each gestational week were calculated. Each individual D-dimer was normalized by transformation into percentiles for the relevant gestational age or delivery group. The range in percentage points during the pregnancy and the delivery was calculated, and reference intervals were calculated for each pregnancy trimester, during vaginal delivery and scheduled and emergency cesarean section, and for the first and second day postpartum. Results. D-dimer increased during pregnancy; the maximal fluctuation was approximately 20 percentile points in approximately half of the women. In one out of ten women, the D-dimer values fluctuated by more than 50 percentile points. Conclusions. Due to the biological variation in D-dimer within each individual woman during normal pregnancy, repeated D-dimer measurements are of no clinical use in the evaluation of thromboembolic events during pregnancy.

D-dimer concentration outliers are not rare in at-term pregnant women

OBJECTIVES

To determine the D-dimer levels in pregnant women at term and the differences between pregnant women with different D-dimer levels.

DESIGN AND METHODS

The plasma D-dimer concentrations in pregnant women at term were identified in a cross-sectional study. The clinical indicators that are potentially relevant to D-dimer levels were compared between the pregnant women with different D-dimer levels (i.e., normal, mildly increased, and severely increased).

RESULTS

There were always some D-dimer concentration outliers in the pregnant women at term regardless of the presence or absence of complications, and there were no significant differences in maternal age, gestational age, gravidity, parity, blood count, blood coagulation, or liver function between the pregnant women with different D-dimer levels.

CONCLUSIONS

D-dimer levels may vary significantly during pregnancy for unknown reasons. This variation, particularly in pregnant women at term, might lead to questionable diagnostic information regarding coagulation.

Haematological problems in obstetrics

Physiologic changes occur during pregnancy, which influence normal haematologic values and impact the diagnosis and management of haematologic disease in pregnancy. Physiologic changes of pregnancy also commonly lead to mimicking symptoms of haematologic disease that may prompt investigations for haematologic disease. The toxicity and radiation associated with the diagnostic imaging and pharmacologic management of both benign and malignant haematological conditions during pregnancy present unique challenges. Strategies for diagnosis and treatment must weigh the benefits and risks to the mother while also taking foetal outcome into consideration. In this review, we highlight the common haematologic diseases encountered by obstetricians and try to provide guidance for the most prevalent diagnostic and therapeutic questions. At the other end of the spectrum, we also comment on less common but very challenging haematologic diseases in pregnancy that require multidisciplinary effort to arrive at difficult individual diagnostic and treatment decisions.

Pregnancy and venous thromboembolism: 'TIPPS' for risk stratification

Pregnancy-associated venous thromboembolism (VTE) is a leading cause of maternal mortality, but is relatively uncommon. It is clear that the antepartum and postpartum periods have different magnitudes of risk and distinct risk factors for VTE and therefore must be considered separately. Absolute daily risks of VTE must be understood and explored when deciding to prescribe antepartum or postpartum thromboprophylaxis and must also be balanced against the downsides of prophylaxis. When the risks for VTE and bleeding are both low, other burdens of thromboprophylaxis must be weighed in and a decision made after an individualized patient values- and patient preferences-based discussion. Risk stratification is essential to ensure that the practicing clinician strikes the right balance.

Biomarkers from late pregnancy to 6 weeks postpartum in HIV-infected women who continue versus discontinue antiretroviral therapy after delivery

BACKGROUND

Women who use antiretroviral therapy (ART) solely for the prevention of mother-to-child transmission of HIV discontinue postpartum. We hypothesized that women discontinuing ART by 6 weeks postpartum ("discontinuers") would have elevated postpartum inflammatory biomarker levels relative to women remaining on ART postpartum ("continuers").

METHODS

Data from HIV-infected pregnant women enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials Group P1025 with CD4 counts >350 cells per cubic millimeter before initiating ART or first pregnancy CD4 counts >400 cells per cubic millimeter after starting ART and with available stored plasma samples at >20 weeks of gestation, delivery, and 6 weeks postpartum were analyzed. Plasma samples were tested for highly sensitive C-reactive protein, D-dimer, and interleukin-6. We used longitudinal linear spline regression to model biomarkers over time.

RESULTS

Data from 128 women (65 continuers and 63 discontinuers) were analyzed. All biomarkers increased from late pregnancy to delivery, then decreased postpartum (slopes different from 0, P < 0.001). Continuers had a steeper decrease in log D-dimer between delivery and 6 weeks postpartum than discontinuers (P = 0.002).

CONCLUSIONS

In contrast to results from treatment interruption studies in adults, both ART continuers and ART discontinuers had significant decreases in the levels of D-dimer, highly sensitive C-reactive protein, or interleukin-6 postpartum. Continuation was associated with a more rapid decline in D-dimer levels compared with discontinuation.

Changes in d-dimer levels in pregnant women according to gestational week

We performed a retrospective review of medical charts regarding blood d-dimer levels determined cross-sectionally by the latex agglutination assay in 1952 samples from 1185 women to determine changes in d-dimer levels according to the stage of pregnancy. Three of 17 women in whom further investigations were performed were found to have clinical venous thromboembolism (VTE). The median and 95th percentile values of d-dimer (μg/mL) in the 1182 women without clinical VTE, 0.54 and 2.41 at gestational week (GW) 4-13, increased gradually to 1.22 and 5.03 at GW 14-27, 1.81 and 6.18 at GW 28-35, and 2.13 and 5.85 at GW 36-42, respectively. A total of nine women (0.76%), including three women with clinical VTE, exhibited a d-dimer level >14.0μg/mL, which was well above the 99th percentile for any stage of pregnancy. Thus, 3 (33%) of the nine with a d-dimer level >14μg/mL developed clinical VTE, while none of the remaining 1176 women with a d-dimer level ⩽14μg/mL developed clinical VTE. Although further prospective studies are required, our results suggested that there is a certain cut-off d-dimer value that would allow us to differentiate between pregnant women with and without clinical VTE.

A model for calculating the within-subject biological variation and likelihood ratios for analytes with a time-dependent change in concentrations; exemplified with the use of D-dimer in suspected venous thromboembolism in healthy pregnant women

BACKGROUND

Within-subject biological variation and reference change value (RCV) are difficult to calculate for an analyte with a changing concentration. The aim of this study was to develop a model to examine if it was possible to transform an analyte with a time-dependent change in concentration into a 'steady-state' situation by the use of 'multiples of the median' (MoM) and its natural logarithm (lnMoM). In addition, we wanted to extend the RCV concept, using likelihood and odds ratios, to calculate the post-test probabilities for disease. D-dimer in pregnancy is used as an example.

METHODS

Blood samples from 18 healthy pregnant and 18 healthy non-pregnant women were collected every fourth week. MoM of the D-dimer concentrations was calculated for each four-week interval to obtain a 'steady-state' situation for the D-dimer concentrations. The 'normalized' values were then transformed to the lnMoM to obtain a Gaussian distribution, used for the estimation of biological variation.

RESULTS

Median D-dimer concentrations increased six-fold during pregnancy. Within-subject variation (SD) of lnMoM D-dimer was 0.27 during pregnancy and 0.23 in non-pregnant women, with RCVs of 0.72 and 0.90, respectively.

CONCLUSIONS

By using the lnMoM model, an increasing concentration of an analyte can be transformed to a steady-state situation and the within-subject biological variation and its derived parameters can be calculated.

Venous thromboembolism associated with pregnancy and hormonal therapy

Venous thromboembolism (VTE) is a major cause of maternal morbidity and mortality during or early after pregnancy and in women taking hormonal therapy for contraception or for replacement therapy. Post-thrombotic syndrome, including leg oedema and leg pain, is an unrecognized burden after pregnancy-related VTE, which will affect more than two of five women. Women with a prior VTE, a family history of VTE, certain clinical risk factors and thrombophilia are at considerably increased risk both for pregnancy-related VTE and for VTE on hormonal therapy. This review critically assesses the epidemiology and risk factors for pregnancy-related VTE and current guidelines for prophylaxis and treatment. We also provide information on the risk of VTE related to hormonal contraception and replacement therapy.

Diagnosis and treatment of deep-vein thrombosis and approach to venous thromboembolism in obstetrics and gynecology

Deep vein thrombosis (DVT) is a common condition in which the approach to its diagnosis has evolved over the years. Currently, an algorithm strategy combining pre-test probability, D-Dimer testing and compression ultrasound imaging allows for safe and convenient investigation of suspected lower-extremity thrombosis. Patients with low pre-test probability and a negative D-Dimer test result can have proximal DVT excluded without the need for diagnostic imaging. The mainstay of treatment of DVT is anticoagulation therapy, whereas interventions such as thrombolysis and placement of inferior vena cava filters are reserved for special situations. The use of low-molecular-weight heparin (LMW) allows for outpatient management of most patients with DVT. The duration of anticoagulation therapy depends on whether the primary event was idiopathic or secondary to a transient risk factor. More research is required to optimally define the factors that predict an increased risk of recurrent DVT to determine which patients can benefit from extended anticoagulant therapy. DVT is also a serious problem in the antenatal and postpartum period of pregnancy. Thromboembolic complications are the leading cause of both maternal and fetal morbidity and mortality. The incidence of venous thromboembolism during normal pregnancy is six-fold higher than in the general female population of childbearing age. The treatment of DVT during pregnancy deserves special mention, since oral anticoagulation therapy is generally avoided during pregnancy because of the teratogenic effects in the first trimester and the risk of fetal intracranial bleeding in the third trimester. LMW heparin is the treatment of choice for DVT during pregnancy. If acute DVT occurs near term, interrupting anticoagulation therapy may be hazardous because of the risk of pulmonary embolism. In this situation, placement of a retrievable inferior vena cava filter must be considered. However, there is no consensus as to what the appropriate dose should be and whether anti-Xa levels need to be monitored.

D-dimer testing in laboratory practice

BACKGROUND

D-dimer is a reliable and sensitive index of fibrin deposition and stabilization. As such, its presence in plasma should be indicative of thrombus formation. There are many conditions unrelated to thrombosis in which D-dimer concentrations are high, however, making its positive predictive value rather poor.

CONTENT

Notwithstanding these limitations, D-dimer can be regarded as a most valuable laboratory tool to diagnose and manage a vast array of thrombosis-related clinical conditions, including (a) diagnosis of venous thromboembolism (VTE), (b) identification of individuals at increased risk of first thrombotic event (both arterial and venous), (c) identification of individuals at increased risk of recurrent VTE, (d) establishment of the optimal duration of secondary prophylaxis after a first episode of VTE, (e) pregnancy monitoring, and (f) diagnosis/monitoring of disseminated intravascular coagulation (DIC). This article is aimed at reviewing the merits and pitfalls of these applications.

SUMMARY

From my analysis of the literature, I draw the following conclusions. (a) D-dimer, as measured by a sensitive test, can be safely used to exclude VTE in symptomatic outpatients, provided that it is used in combination with the pretest clinical probability. (b) High concentrations of D-dimer are associated with an increased risk of recurrent VTE. (c) Patients who present with D-dimer above cutoff after stopping the regular course of oral anticoagulation benefit from extended prophylaxis. (d) Finally, D-dimer can be used as a fibrin-related degradation marker for the diagnosis/management of patients with DIC.

Management of post-partum haemorrhage

Management of post-partum haemorrhage (PPH) involves the treatment of uterine atony, evacuation of retained placenta or placental fragments, surgery due to uterine or birth canal trauma, balloon tamponade, effective volume replacement and transfusion therapy, and occasionally, selective arterial embolization. This article aims at introducing pregnancy- and haemorrhage-induced changes in coagulation and fibrinolysis and their relevant compensatory mechanisms, volume replacement therapy, optimal transfusion of blood products, and coagulation factor concentrates, and briefly cell salvage, management of uterine atony, surgical interventions, and selective arterial embolization. Special attention, respective management, and follow-up are required in women with bleeding disorders, such as von Willebrand disease, carriers of haemophilia A or B, and rare coagulation factor deficiencies. We also provide a proposal for practical instructions in the treatment of PPH.