D-dimers as a screening test for venous thromboembolism in pregnancy: Is it of any use?

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with separate postpartum data were included for 759 individuals with suspected PE (n = 634) or DVT (n = 125), including unpublished data (n = 251).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.

Ten-Year Trend in Advanced Imaging Utilization for Suspected Pulmonary Embolism in Pregnancy

PURPOSE

Advanced imaging is essential to diagnose pulmonary embolism (PE) in pregnancy, but there are associated maternal and fetal radiation risks. The purpose of this study was to evaluate the 10-year trend in advanced imaging utilization for the evaluation of suspected PE in pregnancy.

METHODS

The authors evaluated pregnant women with advanced imaging using CT pulmonary angiography (CTPA) or lung scintigraphy (LS) for evaluation of suspected PE presenting to two tertiary hospitals from 2007 to 2016. The rate of imaging was evaluated relative to positive PE rate and local pregnancy rate. positive PE was defined as a new acute PE finding on any advanced imaging within 3 days of first advanced imaging test. Local pregnancy rates were defined per 1,000 pregnancies in the county serviced by both hospitals. Chi-square testing was used to evaluate statistical significance (P < .05) in the utilization trend of advanced imaging and relative to local pregnancy rates and evaluations positive for PE.

RESULTS

A total of 707 pregnant patients were identified, of whom 92.5% (n = 654) underwent CTPA and 7.5% (n = 53) underwent LS. Regression analysis showed an average increase of 5.2 advanced imaging studies per year (P < .001), with 61 and 105 studies performed in 2007 and 2016, respectively. Additionally, there was an average increase of 0.08 (P < .001) advanced imaging studies per 1,000 local pregnancies per year, doubling from 0.7 in 2007 to 1.4 in 2016 (P < .001). Finally, there was a decrease of 0.004 (P = .009) in advanced imaging positive for PE, from 3% (2 of 61) in 2007 to 0% (0 of 100) in 2016.

CONCLUSIONS

Advanced imaging utilization increased by 72% over the 10-year window, driven by higher use of CTPA. Although the detection rate of PE on advanced imaging has decreased, the utilization rate among pregnant patients doubled during this period. These results highlight the need to consider the radiation risks and costs of advanced imaging in specific patient populations.

Development and validation of a novel model to predict pulmonary embolism in cardiology suspected patients: A 10-year retrospective analysis

As there are no predictive models for pulmonary embolism (PE) in patients with suspected PE at cardiology department. This study developed a predictive model for the probability of PE development in these patients. This retrospective analysis evaluated data from 995 patients with suspected PE at the cardiology department from January 2012 to December 2021. Patients were randomly divided into the training and validation cohorts (7:3 ratio). Using least absolute shrinkage and selection operator regression, optimal predictive features were selected, and the model was established using multivariate logistic regression. The features used in the final model included clinical and laboratory factors. A nomogram was developed, and its performance was assessed and validated by discrimination, calibration, and clinical utility. Our predictive model showed that six PE-associated variables (age, pulse, systolic pressure, syncope, D-dimer, and coronary heart disease). The area under the curve - receiver operating characteristic curves of the model were 0.721 and 0.709 (95% confidence interval: 0.676-0.766 and 0.633-0.784), respectively, in both cohorts. We also found good consistency between the predictions and real observations in both cohorts. In decision curve analysis, the numerical model had a good net clinical benefit. This novel model can predict the probability of PE development in patients with suspected PE at cardiology department.

Values of Caprini Risk Assessment Scale and D-Dimer for Predicting Venous Thromboembolism During Puerperium

Purpose

To evaluate the predictive value of the combination of the Caprini risk assessment model (RAM) and D-dimer for venous thromboembolism (VTE) during puerperium.

Patients and Methods

This was a retrospective case-control study. Thirty-one puerperium patients with VTE were included as cases, and 279 puerperium women without VTE were matched to cases according to age, number of fetuses, birth day and delivery mode at the ratio of 9:1. Demographic data, clinical data and laboratory parameters within postpartum 24 h were collected. Multivariate analysis, employing the forward stepwise model, was conducted to identify independent factors associated with VTE during puerperium. The predictive values of Caprini RAM, D-dimer and their combination were evaluated using receiver operating characteristic (ROC) curve, and the area under curve (AUC) was compared using Z test.

Results

Univariate analysis demonstrated that there were significant differences in D-dimer levels, Caprini score, scarred uterus, adherent placenta, postpartum hemorrhage and intrauterine infection between cases and controls (P<0.05). Multivariate analysis demonstrated that D-dimer levels (OR: 1.754, 95% CI: 1.237-3.182), Caprini score (OR: 1.209, 95% CI: 1.058-2.280), scarred uterus (OR: 1.978, 95% CI: 1.258-3.794), postpartum hemorrhage (OR: 2.276, 95% CI: 1.334-4.347) and intrauterine infection (OR: 2.575, 95% CI: 1.463-4.618) were independently associated with VTE during puerperium with adjustment for adherent placenta and fetal birth weight. The AUCs of D-dimer levels, Caprini score and their combination were 0.748 (SE: 0.030, 95% CI: 0.688-0.807), 0.647 (SE: 0.035, 95% CI: 0.578-0.716) and 0.840 (SE: 0.025, 95% CI: 0.791-0.888). Combination prediction had a higher AUC compared with that of independent prediction (0.840 vs 0.748, Z=2.356, P=0.009; 0.840 vs 0.647, Z=4.487, P<0.001) with a sensitivity of 83.9% and specificity of 80.3%.

Conclusion

The combination of the Caprini RAM and D-dimer could significantly elevate the predictive value for VTE during puerperium, and this new tool had the potential in the prediction of VTE during puerperium.

Diagnostic test accuracy of D-dimer with or without a clinical decision rule in peripartum patients with suspected venous thromboembolism: A systematic review and meta-analysis

BACKGROUND

Pregnancy and the peripartum period is a hypercoagulable state increasing the risk of venous thromboembolism (VTE). There may be a role in utilising D-dimer in the peripartum setting.

AIMS

The purpose of this review was to summarise the latest evidence regarding the diagnostic accuracy of D-dimer in the peripartum setting with or without the addition of clinical decision rules.

METHODS

We searched PubMed and CENTRAL databases to identify articles that included studies of women who had suspected VTE, underwent a D-dimer index test to rule out VTE and where radiological imaging or clinical follow-up, to a minimum of 30 days, was used as the reference standard.

RESULTS

We included 11 studies in the systematic review and meta-analysis. The log diagnostic odds ratio (DOR) for identifying VTE using D-dimer was 1.56 (95% confidence interval (CI) 0.59-2.52). The pooled sensitivity was 87% (95% CI 76.8-93%), specificity was 63.2% (95% CI 47.1-76.7%), and the area under receiver operator characteristic (ROC) curves was 0.76. We included four studies evaluating D-dimer combined with YEARS to detect VTE. The log DOR for identifying VTE using D-dimer combined with YEARS was 1.13 (95% CI 0.005-2.25). The pooled sensitivity was 89.8% (95% CI 60.2-98.1%), specificity was 65.7% (95% CI 54.7-75.2%) and the area under ROC for studies included with the YEARS clinical decision rule was 0.49.

CONCLUSION

This review highlighted that D-dimer use in the peripartum period for detection of VTE had a high sensitivity and high DOR but a poor area under ROC, which may limit its use in clinical practice.

Venous Thromboembolism in Pregnancy: Challenges and Solutions

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

Developing a nomogram-based scoring model to estimate the risk of pulmonary embolism in respiratory department patients suspected of pulmonary embolisms

Objective

Pulmonary embolisms (PE) are clinically challenging because of their high morbidity and mortality. This study aimed to create a nomogram to accurately predict the risk of PE in respiratory department patients in order to enhance their medical treatment and management.

Methods

This study utilized a retrospective method to collect information on medical history, complications, specific clinical characteristics, and laboratory biomarker results of suspected PE patients who were admitted to the respiratory department at Affiliated Dongyang Hospital of Wenzhou Medical University between January 2012 and December 2021. This study involved a total of 3,511 patients who were randomly divided into a training group (six parts) and a validation group (four parts) based on a 6:4 ratio. The LASSO regression and multivariate logistic regression were used to develop a scoring model using a nomogram. The performance of the model was evaluated using receiver operating characteristic curve (AUC), calibration curve, and clinical decision curve.

Results

Our research included more than 50 features from 3,511 patients. The nomogram-based scoring model was established using six predictive features including age, smoke, temperature, systolic pressure, D-dimer, and fibrinogen, which achieved AUC values of 0.746 in the training cohort (95% CI 0.720-0.765) and 0.724 in the validation cohort (95% CI 0.695-0.753). The results of the calibration curve revealed a strong consistency between probability predicted by the nomogram and actual probability. The decision curve analysis (DCA) also demonstrated that the nomogram-based scoring model produced a favorable net clinical benefit.

Conclusion

In this study, we successfully developed a novel numerical model that can predict the risk of PE in respiratory department patients suspected of PE, which can not only appropriately select PE prevention strategies but also decrease unnecessary computed tomographic pulmonary angiography (CTPA) scans and their adverse effects.

A nomogram for predicting the risk of pulmonary embolism in neurology department suspected PE patients: A 10-year retrospective analysis

Objective

The purpose of this retrospective study was to establish a numerical model for predicting the risk of pulmonary embolism (PE) in neurology department patients.

Methods

A total of 1,578 subjects with suspected PE at the neurology department from January 2012 to December 2021 were considered for enrollment in our retrospective study. The patients were randomly divided into the training cohort and the validation cohort in the ratio of 7:3. The least absolute shrinkage and selection operator regression were used to select the optimal predictive features. Multivariate logistic regression was used to establish the numerical model, and this model was visualized by a nomogram. The model performance was assessed and validated by discrimination, calibration, and clinical utility.

Results

Our predictive model indicated that eight variables, namely, age, pulse, systolic pressure, hemoglobin, neutrophil count, low-density lipoprotein, D-dimer, and partial pressure of oxygen, were associated with PE. The area under the receiver operating characteristic curve of the model was 0.750 [95% confidence interval (CI): 0.721–0.783] in the training cohort and 0.742 (95% CI: 0.689–0.787) in the validation cohort, indicating that the model showed a good differential performance. A good consistency between the prediction and the real observation was presented in the training and validation cohorts. The decision curve analysis in the training and validation cohorts showed that the numerical model had a good net clinical benefit.

Conclusion

We established a novel numerical model to predict the risk factors for PE in neurology department suspected PE patients. Our findings may help doctors to develop individualized treatment plans and PE prevention strategies.

Patient and Fetal Radiation-Induced Malignancy Risk From Imaging For Evaluation of Pulmonary Embolism in Pregnancy

BACKGROUND

Imaging for diagnosis of suspected pulmonary embolism in pregnancy presents radiation concerns for patient and fetus.

OBJECTIVES

Estimate the risks of radiation-induced breast cancer and childhood leukemia from common imaging techniques for the evaluation of suspected pulmonary embolism in pregnancy.

METHODS

Breast and uterine absorbed doses for various imaging techniques were input into the National Cancer Institute Radiation Risk Assessment Tool to calculate risk of breast cancer for the patient and childhood leukemia for the fetus. Absorbed doses were obtained by synthesizing data from a recent systematic review and the International Commission on Radiological Protection. Primary outcomes were the estimated excess incidences of breast cancer and childhood leukemia per 100,000 exposures.

RESULTS

Baseline incidences of breast cancer for a 30-year-old woman and childhood leukemia for a male fetus were 13,341 and 939, respectively. Excess incidences of breast cancer were 0.003 and 0.275 for a single and two-view chest radiograph, respectively, 9.53 and 20.6 for low- and full-dose computed tomography pulmonary angiography (CTPA), respectively, 0.616 and 2.54 for low- and full-dose perfusion scan, respectively, and 0.732 and 2.66 for low- and full-dose ventilation perfusion scan, respectively. Excess incidences of childhood leukemia were 0.004 and 0.007 for a single and two-view chest radiograph, respectively, 0.069 and 0.490 for low- and full-dose CTPA, respectively, 0.359 and 1.47 for low- and full-dose perfusion scan, respectively, and 0.856 and 1.97 for low- and full-dose ventilation perfusion scan, respectively.

CONCLUSION

Excess cancer risks for all techniques were small relative to baseline cancer risks, with CTPA techniques carrying slightly higher risk of breast cancer for the patient and ventilation perfusion techniques a higher risk of childhood leukemia.

Pulmonary Embolism in Pregnancy

Pulmonary embolism during and after pregnancy remains a significant contributor to maternal morbidity and mortality. Symptoms that would be a clear indicator of a pulmonary embolus in the nonpregnant population can be masked by pregnancy and its routine pregnancy-related symptoms. To affect a reduction in this severe maternal mortality indicator, physicians need to maintain a high degree of suspicion coupled with expedient testing.

Predictive Model for Pulmonary Embolism in Pregnant and Postpartum Women: A 10-Year Retrospective Study

Background: Pulmonary embolism (PE) in pregnant and postpartum women is fatal, and risk assessment is crucial for effective and safe management, the aim of this retrospective study was to establish a nomogram for predicting the risk of PE in pregnant and postpartum women. Methods: Totally 343 subjects suspected of PE at the Obstetrics Department of Affiliated Dongyang Hospital of Wenzhou Medical University from January 2012 to December 2021 were retrospective analyzed in our study. Pregnant women suspected of PE and who underwent computed tomographic pulmonary angiography examination were included in the study. The least absolute shrinkage and selection operator regression technique was used to select the best prediction features, and multivariate logistic regression is used to build the prediction model. Bootstrap resampling 1000 times was used to validate the model visualized by nomogram. Evaluate the performance of the model from three aspects: identification, calibration and clinical utility. Results: Our predictive model indicated that chest tightness, anhelation, lactate, and D-dimer were associated with PE. The area under the receiver operating characteristic curve of the model was 0.836 (95% CI: [0.770-0.902]), indicating that our model had a good differential diagnostic performance. Good consistency between prediction and real observation was presented as the calibration curve. Decision curve analysis indicated that our model had a good net clinical benefit. Conclusions: We developed a novel numerical model for selecting risk factors for PE in pregnant and postpartum women. Our results may help obstetricians and gynaecologists to develop individualized treatment plans and PE prevention strategies.

Utilization of a Guideline-recommended Imaging Paradigm for Pregnant Patients With Suspicion of Pulmonary Embolism

PURPOSE

A dose reduction imaging paradigm utilizing chest x-ray (CXR) to triage between computed tomography pulmonary angiography (CTPA) and lung scintigraphy (LS) was introduced in 2001 and adopted in 2012 by the American Thoracic Society/Society of Thoracic Radiology (ATS) guideline for the evaluation of pulmonary embolism in pregnancy. We aimed to assess the utilization of this imaging paradigm preadoption and postadoption by the ATS guideline, and identify factors associated with its utilization.

MATERIALS AND METHODS

This retrospective cohort study evaluated consecutive pregnant patients who received CTPA or LS for the evaluation of pulmonary embolism in pregnancy at 2 tertiary hospitals between September 2008 and March 2017, excluding 2012 for guideline release washout. Utilization of the imaging paradigm was defined per patient by the use of CXR before advanced imaging, with CTPA performed following positive CXR and LS performed following negative CXR. Multivariate analyses were performed to assess factors associated with utilization of the imaging paradigm. P <0.05 is considered significant.

RESULTS

Overall, 9.8% (63/643) of studies utilized the dose reduction imaging paradigm, 13.3% (34/256) before the guidelines, and 7.5% (29/387) after. Multivariable analysis showed that the dose reduction imaging paradigm utilization was higher for inpatients (odds ratio [OR]: 4.5) and outpatients (OR: 3.1) relative to the emergency department patients, and lower for second (OR: 0.3) and third (OR: 0.2) trimester patients, without significant differences by study priority, patient age, or patient race.

CONCLUSIONS

Guideline-recommended dose reduction imaging paradigm utilization was low, and decreased after guideline publication. Utilization varied by patient setting and trimester, which are potential targets for interventions to improve guideline compliance.

Comparison of guidelines for evaluation of suspected PE in pregnancy: a cost-effectiveness analysis

BACKGROUND

Pulmonary embolism (PE) remains a leading cause of maternal mortality, yet diagnosis remains challenging. International diagnostic guidelines vary significantly in their recommendations, making it difficult to determine an optimal policy for evaluation.

RESEARCH QUESTION

Which societal-level diagnostic guideline for evaluation of suspected PE in pregnancy is an optimal policy in terms of its cost-effectiveness?

STUDY DESIGN AND METHODS

We constructed a complex Markov decision model to evaluate the cost-effectiveness of each identified societal guideline for diagnosis of PE in pregnancy. Our model accounted for risk stratification, empiric treatment, diagnostic testing strategies, as well as short- and long-term effects from PE, treatment with low-molecular weight heparin, and radiation exposure from advanced imaging. We considered clinical and cost outcomes of each guideline from a U.S. health care system perspective with a lifetime horizon. Clinical effectiveness and costs were measured in time-discounted quality-adjusted life years (QALYs) and U.S. dollars respectively. Strategies were compared using the incremental cost-effectiveness ratio (ICER) with a willingness-to-pay threshold of $100,000 per QALY. One-way, multi-way, and probabilistic sensitivity analyses were performed.

RESULTS

We identified six international societal-level guidelines. Base-case analysis showed the guideline proposed by the American Thoracic Society-Society of Thoracic Radiology (ATS-STR) yielded the highest health benefits (22.90 QALYs) and was cost-effective, with an ICER of $7,808 over the guideline proposed by the Australian Society of Thrombosis and Haemostasis and the Society of Obstetric Medicine of Australia and New Zealand (ASTH-SOMANZ). All remaining guidelines were dominated. The ATS-STR guideline-recommended strategy yielded an expected additional 2.7 QALYs per 100 patients evaluated over the ASTH-SOMANZ. Conclusions were robust to sensitivity analyses, with the ATS-STR guideline optimal in 86% of probabilistic sensitivity analysis scenarios.

INTERPRETATION

The ATS-STR guideline for diagnosis of suspected PE in pregnancy is cost-effective and generates better expected health outcomes than guidelines proposed by other medical societies.

D-dimer to rule out venous thromboembolism during pregnancy: A systematic review and meta-analysis

BACKGROUND

The usefulness of D-dimer measurement to rule out venous thromboembolism (VTE) during pregnancy is debated.

OBJECTIVES

We performed a systematic review and meta-analysis to investigate the safety of D-dimer to rule out acute VTE in pregnant women with suspected pulmonary embolism and/or deep vein thrombosis.

METHODS

Two reviewers independently identified studies through PubMed and Embase until June 2021, week 1. We supplemented our search by manually reviewing reference lists of all retrieved articles, clinicalTrials.gov, and reference literature. Prospective or retrospective studies in which a formal diagnostic algorithm was used to evaluate the ability of D-dimer to rule out VTE during pregnancy were eligible.

RESULTS

We identified 665 references through systematic database and additional search strategies; 45 studies were retrieved in full, of which four were included, after applying exclusion criteria. Three studies were prospective, and one had a retrospective design. The 3-month thromboembolic rate in pregnant women left untreated after a negative D-dimer was 1/312 (0.32%; 95% CI, 0.06-1.83). The pooled estimate values were 99.5% for sensitivity (95% CI, 95.0-100.0; I², 0%) and 100% for negative predictive value (95% CI, 99.19-100.0; I², 0%). The prevalence of VTE and the yield of D-dimer were 7.4% (95% CI, 3.8-12; I², 83%) and 34.2% (95% CI, 15.9-55.23; I², 89%) respectively.

CONCLUSION

Our results suggest that D-dimer allows to safely rule out VTE in pregnant women with suspected VTE and a disease prevalence consistent with a low/intermediate or unlikely pretest probability.

Canadian Society of Thoracic Radiology/Canadian Association of Radiologists Best Practice Guidance for Investigation of Acute Pulmonary Embolism, Part 1: Acquisition and Safety Considerations

Acute pulmonary embolism (APE) is a well-recognized cause of circulatory system compromise and even demise which can frequently present a diagnostic challenge for the physician. The diagnostic challenge is primarily due to the frequency of indeterminate presentations as well as several other conditions which can have a similar clinical presentation. This often obliges the physician to establish a firm diagnosis due to the potentially serious outcomes related to this disease. Computed tomography pulmonary angiography (CTPA) has increasingly cemented its role as the primary investigation tool in this clinical context and is widely accepted as the standard of care due to several desired attributes which include great accuracy, accessibility, rapid turn-around time and the ability to suggest an alternate diagnosis when APE is not the culprit. In Part 1 of this guidance document, a series of up-to-date recommendations are provided to the reader pertaining to CTPA protocol optimization (including scan range, radiation and intravenous contrast dose), safety measures including the departure from breast and gonadal shielding, population-specific scenarios (pregnancy and early post-partum) and consideration of alternate diagnostic techniques when clinically deemed appropriate.

The Predictive Value of d-Dimer Test for Venous Thromboembolism During Puerperium: A Prospective Cohort Study

The aim of this study was to investigate the d-dimer for prediction of venous thromboembolism (VTE) events in puerperium and to identify other risk factors associated with the occurrence of VTE. This was a prospective observational cohort study, which included 16 127 women who gave birth after 28 weeks of gestation at Women’s Hospital of Zhejiang University, School of Medicine, from January 2016 to December 2016. Data including basic maternal and fetal characteristics, pregnancy complications, and predictive biomarkers within postpartum 24 hours including d-dimer, platelet, and fibrinogen were collected for analyses. In the cohort study, 19 (0.12%) women were identified as VTE, including 1 pulmonary embolism event and 18 deep venous thrombosis events. The receiver operating characteristic curve analysis suggested the best cutoff point for d-dimer level within postpartum 24 hours was 3.695 mg/L, with a specificity of 75.5% and a sensitivity of 73.7%, and there was no statistical correlation between fibrinogen and VTE, as well as between platelets and VTE. On multivariate analysis, age ≥35 years (odds ratio [OR] = 2.895, 95% confidence interval [CI]: 1.079-7.773), scarred uterus (OR = 3.894, 95% CI: 1.234-12.282), intrauterine infection (OR = 7.214, 95% CI: 1.519-34.262), antiphospholipid syndrome (OR = 199.530, 95% CI: 15.152-2627.529), d-dimer ≥3.70 mg/L (OR = 7.573, 95% CI: 2.699-21.247), and emergency cesarean delivery (OR = 23.357, 95% CI: 2.819-193.508) were independently associated with VTE in puerperium. We concluded that d-dimer ≥3.70 mg/L was an independent predictor of VTE during puerperium and d-dimer testing was necessary for perinatal women.

Comparison of international societal guidelines for the diagnosis of suspected pulmonary embolism during pregnancy

Pregnancy-associated pulmonary embolism is one of the leading causes of maternal mortality. Diagnosis of pulmonary embolism in pregnancy is challenging, with symptoms of pulmonary embolism mimicking those of pregnancy. Several key components such as clinical prediction tools, risk stratification, laboratory tests, and imaging widely used for diagnosis of pulmonary embolism in the non-pregnant population show limitations for diagnosis in pregnancy. Further, because of the difficulty of studying pregnant patients, high-quality research evaluating the performance of these diagnostic components in pregnancy is scarce. Seven international medical society guidelines present clinical diagnostic pathways for evaluation of pulmonary embolism in pregnancy that show conflicting recommendations on the use of these diagnostic components. This Review assesses all key components of diagnostic clinical pathways recommended by guidelines for evaluation of pulmonary embolism in pregnancy, reviews current evidence, compares the guideline recommendations with respect to each key component, and provides our preferred diagnostic pathway. It provides the guidelines and available data needed for informed decision making to diagnose pulmonary embolism in pregnancy.

Evaluation of CTPA interpreted as limited in pregnant patients suspected for pulmonary embolism

PURPOSE

The purpose of this study is to determine the rates of CT pulmonary angiography (CTPA) interpreted as limited and severely limited in pregnant patients suspected for pulmonary embolism (PE), and to evaluate factors that influence these rates.

METHODS

This is a retrospective study with CTPA for evaluation of PE in pregnancy across a large health system from 2006 to 2017. CTPA was classified as limited from the radiology report with a subset of those studies classified as severely limited. Bivariate and multivariate analysis was performed for limited and severely limited rates with maternal age and patient size as a continuous variable and race, trimester, patient location study priority status, and result of chest radiograph before CTPA as categorical variables.

RESULTS

874 patients with 33% of studies limited and 4% of studies severely limited. Multivariate logistic regression of CTPA studies revealed decreasing patient age (OR 0.967, p = 0.0129) and increasing patient size (OR 1.013, p < 0.0001). Studies performed in the second trimester (OR 1.869, p = 0.0242) and third trimester (OR 2.314, p = 0.0021) were more likely to be reported as limited (each p < 0.05). Increasing patient size (OR 1.017, p = 0.0046) was the only significant predictor of severely limited versus non-severely limited studies.

CONCLUSION

CTPA interpreted as limited in pregnancy are common and may be associated with younger age, larger patient size, and second and third trimesters. However, severely limited interpretations are much less common, with patient size the only significant predictor.

New evidence in diagnosis of pulmonary embolism during pregnancy

Diagnosis of pulmonary embolism (PE) in pregnancy is notoriously difficult and lacking high quality evidence. Three studies (DiPEP, ARTEMIS and CT-PE-Pregnancy) evaluating a systematic approach to PE diagnosis have recently been published. DiPEP is a retrospective case-control study that found a poor utility of clinical decision rules or D-dimer testing for PE diagnosis in pregnancy. ARTEMIS and CT-PE-Pregnancy are well conducted prospective management studies that proposed two algorithms with different clinical decision rules and D-dimer criteria for the diagnosis of PE in pregnancy. They included few events in high risk patients, which makes difficult the assessment of both algorithm's safety in women with a high probability of PE. Considering this new evidence, D-dimer testing might be useful to avoid radiation imaging in pregnant women considered at low risk for PE. In contrast, a negative D-dimer cannot be considered sufficiently safe to rule out PE when clinicians estimate that PE is the most likely diagnosis.

Predictors of radiation dose for CT pulmonary angiography in pregnancy across a multihospital integrated healthcare network

PURPOSE

There is a large range of published effective radiation dose for CTPA during pregnancy. The purpose of our study is to determine the mean effective radiation dose and predictors of mean effective radiation dose for CTPA in pregnant patients across a multihospital integrated healthcare network.

METHODS

This retrospective study evaluates pregnant women who had a CTPA as the first primary advanced imaging test for evaluation of PE in a multihospital integrated healthcare network from January 2012-April 2017. Patient and CT-related data were obtained from the electronic health record and Radimetrics server (Radimetrics Inc, Bayer). DLP was recorded and effective radiation dose in mSv was determined using a conversation factor of 0.014 mSv·mGy^-¹·cm^-¹. Patient size was determined by water equivalent diameter. Bivariate and multivariate analysis were performed for effective radiation dose based on patient and CT factors.

RESULTS

In the 534 CTPA exams, the mean effective radiation dose was 3.96 mSv. Bivariate analysis showed significant differences in radiation dose by trimester, p = 0.042: first trimester 4.52 mSv, second trimester 3.73 mSv, and third trimester 3.95 mSv. Multivariable analysis demonstrated CTPA during first trimester, increasing mAs, kVp, scan length, patient size, and use of mAs modulation, as well as decreasing pitch, to be predictive of higher effective radiation dose.

CONCLUSION

Mean effective radiation dose was on the lower end of published studies. Trimester was a statistically significant predictor of effective radiation dose when accounting for known predictors of radiation dose.

ACOG Practice Bulletin No. 196: Thromboembolism in Pregnancy

Women who are pregnant or in the postpartum period have a fourfold to fivefold increased risk of thromboembolism compared with nonpregnant women (). Approximately 80% of thromboembolic events in pregnancy are venous (), with a prevalence of 0.5-2.0 per 1,000 pregnant women (). Venous thromboembolism (VTE) is one of the leading causes of maternal mortality in the United States, accounting for 9.3% of all maternal deaths ().The prevalence and severity of this condition during pregnancy and the peripartum period warrant special consideration of management and therapy. Such therapy includes the treatment of acute thrombotic events and prophylaxis for those at increased risk of thrombotic events. The purpose of this document is to provide information regarding the risk factors, diagnosis, management, and prevention of thromboembolism, particularly VTE in pregnancy. This Practice Bulletin has been revised to reflect updated guidance regarding screening for thromboembolism risk and management of anticoagulation around the time of delivery.

Selecting pregnant or postpartum women with suspected pulmonary embolism for diagnostic imaging: the DiPEP diagnostic study with decision-analysis modelling

BACKGROUND

Pulmonary embolism (PE) is a leading cause of death in pregnancy and post partum, but the symptoms of PE are common in normal pregnancy. Simple diagnostic tests are needed to select women for diagnostic imaging.

OBJECTIVE

To estimate the accuracy, effectiveness and cost-effectiveness of clinical features, decision rules and biomarkers for selecting pregnant or postpartum women with a suspected PE for imaging.

DESIGN

An expert consensus study to develop new clinical decision rules, a case-control study of women with a diagnosed PE or a suspected PE, a biomarker study of women with a suspected PE or diagnosed deep-vein thrombosis (DVT) and decision-analysis modelling.

SETTING

Emergency departments and consultant-led maternity units.

PARTICIPANTS

Pregnant/postpartum women with a diagnosed PE from any hospital reporting to the UK Obstetric Surveillance System research platform and pregnant/postpartum women with a suspected PE or diagnosed DVT at 11 prospectively recruiting sites.

INTERVENTIONS

Clinical features, decision rules and biomarkers.

MAIN OUTCOME MEASURES

Sensitivity, specificity, area under receiver operating characteristic (AUROC) curve, quality-adjusted life-years (QALYs) and health-care costs.

RESULTS

The primary analysis involved 181 women with PE and 259 women without PE in the case-control study and 18 women with DVT, 18 with PE and 247 women without either in the biomarker study. Most clinical features showed no association with PE. The AUROC curves for the clinical decision rules were as follows: primary consensus, 0.626; sensitive consensus, 0.620; specific consensus, 0.589; PE rule-out criteria, 0.621; simplified Geneva score, 0.579; Wells's PE criteria (permissive), 0.577; and Wells's PE criteria (strict), 0.732. The sensitivities and specificities of the D-dimer measurement were 88.4% and 8.8%, respectively, using a standard threshold, and 69.8% and 32.8%, respectively, using a pregnancy-specific threshold. Previous venous thromboembolism, long-haul travel, multiple pregnancy, oxygen saturation, recent surgery, temperature and PE-related chest radiograph abnormality were predictors of PE on multivariable analysis. We were unable to derive a rule through multivariable analysis or recursive partitioning with adequate accuracy. The AUROC curves for the biomarkers were as follows: activated partial thromboplastin time - 0.669, B-type natriuretic peptide - 0.549, C-reactive protein - 0.542, Clauss fibrinogen - 0.589, enzyme-linked immunosorbent assay D-dimer - 0.668, Innovance D-dimer (Siemens Healthcare Diagnostics Products GmbH, distributed by Sysmex UK Ltd, Milton Keynes, UK) - 0.651, mid-regional pro-atrial natriuretic peptide (MRproANP) - 0.524, prothrombin fragment 1 + 2 - 0.562, plasmin-antiplasmin - 0.639, Prothombin time - 0.613, thrombin generation lag time - 0.702, thrombin generation endogenous potential - 0.559, thrombin generation peak - 0.596, thrombin generation time to peak - 0.655, tissue factor - 0.531 and troponin - 0.597. The repeat analysis excluding women who had received anticoagulation was limited by the small number of women with PE (n = 4). The health economic analysis showed that a strategy of scanning all women with a suspected PE accrued more QALYs and incurred fewer costs than any selective strategy based on a clinical decision rule and was therefore the dominant strategy.

LIMITATIONS

The findings apply specifically to the diagnostic assessment of women with a suspected PE in secondary care.

CONCLUSIONS

Clinical features, decision rules and biomarkers do not accurately, effectively or cost-effectively select pregnant or postpartum women with a suspected PE for diagnostic imaging.

FUTURE WORK

New diagnostic technologies need to be developed to detect PE in pregnancy.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN21245595.

FUNDING DETAILS

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 47. See the NIHR Journals Library website for further project information.

Thrombin generation test as a marker for high risk venous thrombosis pregnancies

Pregnancy is a well-established risk factor for venous thromboembolism and is associated with a state of hypercoagulability. The use of sensitive and specific biological markers to predict risk factors for thrombosis is essential during pregnancy. Our objective was to investigate the usefulness of thrombin generation test (TGT) as a marker to predict the risk of thrombosis in high risk venous thrombosis (HRVT) pregnancies compared to normal pregnancies. This retrospective study enrolled 134 women with HRVT pregnancies, 78 of whom had monozygotic, spontaneous and untreated pregnancies and formed the study group. The control group comprised 106 women with normal pregnancies. Routine assessment of coagulation activation markers: fibrinogen, D-dimer, prothrombin fragments 1 + 2 (F1 + 2), thrombin-antithrombin complexes (TAT) and fibrin monomer complexes (FMC) was performed every 5 weeks in the study group to detect a possible pathological state of hypercoagulability. TGT was performed using platelet-free plasma, 1 and 5 pM tissue factor (TF), supplemented by phospholipids (PL) ± thrombomodulin. Fibrinogen, D-dimer, F1 + 2, and TAT, but not FMC, increased significantly throughout pregnancy in both groups but no difference was shown between the groups. TGT showed an early increase in thrombin generation in both groups, which stabilized during the second month of pregnancy. No correlation was demonstrated between thrombin generation parameters and coagulation activation markers. Based on our results, TGT did not prove conclusive as a marker to predict the risk of thrombosis in HRVT pregnancies. Finding a sensitive and specific biological marker to predict thrombosis risk requires further investigation.

The DiPEP study: an observational study of the diagnostic accuracy of clinical assessment, D-dimer and chest x-ray for suspected pulmonary embolism in pregnancy and postpartum

Objective

To identify clinical features associated with pulmonary embolism (PE) diagnosis and determine the accuracy of decision rules and D‐dimer for diagnosing suspected PE in pregnant/postpartum women

Design

Observational cohort study augmented with additional cases.

Setting

Emergency departments and maternity units at eleven prospectively recruiting sites and maternity units in the United Kingdom Obstetric Surveillance System (UKOSS)

Population

324 pregnant/postpartum women with suspected PE and 198 pregnant/postpartum women with diagnosed PE

Methods

We recorded clinical features, elements of clinical decision rules, D‐dimer measurements, imaging results, treatments and adverse outcomes up to 30 days

Main outcome measures

Women were classified as having PE on the basis of imaging, treatment and adverse outcomes by assessors blind to clinical features and D‐dimer. Primary analysis was limited to women with conclusive imaging to avoid work‐up bias. Secondary analyses included women with clinically diagnosed or ruled out PE.

Results

The only clinical features associated with PE on multivariate analysis were age (odds ratio 1.06; 95% confidence interval 1.01–1.11), previous thrombosis (3.07; 1.05–8.99), family history of thrombosis (0.35; 0.14–0.90), temperature (2.22; 1.26–3.91), systolic blood pressure (0.96; 0.93–0.99), oxygen saturation (0.87; 0.78–0.97) and PE‐related chest x‐ray abnormality (13.4; 1.39–130.2). Clinical decision rules had areas under the receiver‐operator characteristic curve ranging from 0.577 to 0.732 and no clinically useful threshold for decision‐making. Sensitivities and specificities of D‐dimer were 88.4% and 8.8% using a standard threshold and 69.8% and 32.8% using a pregnancy‐specific threshold.

Conclusions

Clinical decision rules and D‐dimer should not be used to select pregnant or postpartum women with suspected PE for further investigation. Clinical features and chest x‐ray appearances may have counter‐intuitive associations with PE in this context.

Tweetable abstract

Clinical decision rules and D‐dimer are not helpful for diagnosing pregnant/postpartum women with suspected PE

Clinical decision rules and D‐dimer are not helpful for diagnosing pregnant/postpartum women with suspected PE.

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.

The diagnostic utility of D-dimer and other clinical variables in pregnant and post-partum patients with suspected acute pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) during pregnancy remains one of the leading causes of maternal morbidity and mortality in the developed world. However, there is a paucity of high-quality evidence resulting in a lack of consensus in managing this group of patients. The aims of the study were to address the diagnostic utility of D-dimer for suspected PE in pregnant and post-partum patients and to identify any clinical presentation variables that are predictors of PE in this group of patients.

METHODS

A retrospective case note review of 152 pregnant and post-partum patients who underwent diagnostic imaging (ventilation/perfusion (V/Q) or computed tomographic pulmonary angiography (CTPA)) for suspected PE at a tertiary teaching hospital from 2007 to 2011 was conducted. The reference range for D-dimer was less than 0.5 mg/L as being normal. The following variables were also assessed in terms of their predictive capability for PE diagnosis in pregnancy: heart rate (HR), mean arterial pressure (MAP), shock index (SI) and A-a gradient.

RESULTS

The application of D-dimer testing for suspected PE in this study population had a sensitivity of 100% (95% CI, 73-100%), specificity of 42% (95% CI, 31-53%) and a likelihood negative ratio of 0. None of the clinical variables were significant predictors of PE according to regression analyses.

CONCLUSIONS

There is supportive evidence that a negative D-dimer result is useful as a means of ruling out PE in pregnant and post-partum patients. However, we need a larger prospective observational study to collaborate the findings.

The DiPEP (Diagnosis of PE in Pregnancy) biomarker study: An observational cohort study augmented with additional cases to determine the diagnostic utility of biomarkers for suspected venous thromboembolism during pregnancy and puerperium

This study aimed to estimate the diagnostic utility of biomarkers for suspected venous thromboembolism (VTE) in pregnancy and the puerperium. Research nurses/midwives collected blood samples from 310 pregnant/postpartum women with suspected pulmonary emboli (PE) and 18 with diagnosed deep vein thrombosis (DVT). VTE was diagnosed using imaging, treatment and adverse outcome data. Primary analysis was limited to women with conclusive imaging (36 with VTE, 247 without). The area under the curve (AUC) for each biomarker was: activated partial thromboplastin time 0·669 (95% confidence interval 0·570-0·768), B-type natriuretic peptide 0·549 (0·453-0·645), C-reactive protein 0·542 (0·445-0·639), Clauss fibrinogen 0·589 (0·476-0·701), D-Dimer (by enzyme-linked immunosorbent assay) 0·668 (0·561-0·776), near-patient D-Dimer 0·651 (0·545-0·758), mid-regional pro-atrial natriuretic peptide 0·524 (0·418-0·630), prothrombin fragment 1 + 2 0·562 (0·462-0·661), plasmin-antiplasmin complexes 0·639 (0·536-0·742), prothombin time 0·613 (0·508-0·718), thrombin generation lag time 0·702 (0·598-0·806), thrombin generation endogenous potential 0·559 (0·437-0·681), thrombin generation peak 0·596 (0·478-0·715), thrombin generation time to peak 0·655 (0·541-0·769), soluble tissue factor 0·531 (0·424-0·638) and serum troponin 0·597 (0·499-0·695). No diagnostically useful threshold for diagnosing or ruling out VTE was identified. In pregnancy and the puerperium, conventional and candidate biomarkers have no utility either for their negative or positive predictive value in the diagnosis of VTE.

Guidance for the diagnosis of pulmonary embolism during pregnancy: Consensus and controversies

Pulmonary embolism (PE) is one of the leading causes of maternal mortality despite a low incidence of PE during pregnancy. Several challenges surround the diagnosis of PE in pregnant women and the existing clinical guidelines provide weak recommendations on selecting the appropriate investigations for suspected PE in pregnancy. The purpose of this narrative review is to compare and contrast the recommendations of current clinical guidelines and review the evidence underpinning the recommendations on the evaluation of suspected PE in pregnancy. Consensus and controversies, knowledge gaps and areas requiring further research will be highlighted.

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.

Frequency of nonthromboembolic imaging abnormalities in pregnant women referred for computed tomography pulmonary arteriography

PURPOSE

The study sought to determine the frequency of nonthromboembolic imaging abnormalities in pregnant women referred for computed tomography pulmonary arteriography (CTPA).

MATERIALS AND METHODS

CTPA studies on 100 consecutive pregnant women performed over a 5-year period were reviewed independently by 2 radiologists, with conflicts resolved by consensus. Age range was 18-43 years (mean 28 years). The presence or absence of pulmonary embolism and of nonthromboembolic imaging abnormalities was recorded. These were graded as A if the abnormalities were thought to provide potential alternative explanations for acute symptoms, B if findings were incidental that required clinical or radiologic follow-up, and C if the findings did not require further action.

RESULTS

Pulmonary embolism was seen in 5 women. In 2 of these additional findings of consolidation and infarction were seen. Ninety-five women did not have pulmonary embolism. Eleven women (12%) had grade A abnormalities; 6 cases of consolidation, 2 cases of lobar collapse, and 3 cases of heart failure with pleural effusions. One woman had a grade B abnormality due to the presence of pulmonary nodules. Ten women had incidental grade C abnormalities.

CONCLUSION

Pulmonary embolism occurs in 5% of pregnant women referred for CTPA. In pregnant women without embolism on CTPA, potential alternative causes for patient symptoms are seen on CT in 12% of cases.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Comparison of markers of coagulation activation and thrombin generation test in uncomplicated pregnancies

INTRODUCTION

Pregnancy is a well-established risk factor for venous thromboembolism, and is associated with a state of hypercoagulability or parameters of thrombin generation. Currently, there is a lack of consensual data on thrombin generation during pregnancy. This study aimed to find a sensitive and specific biological marker of coagulation activation and to identify parameters of thrombin generation.

PATIENTS AND METHODS

The population included 101 women with uncomplicated pregnancies. The objective of this study was to correlate thrombin generation test (measured at 5pM tissue factor, 4μM lipids and without thrombomodulin), with fibrinogen and markers of blood coagulation activation: D-dimer, prothrombin fragments 1+2 (F1+2), thrombin-antithrombin complexes (TAT) and fibrin monomer complexes (FMC) in these women. Internal quality control was performed in each set of experiments.

RESULTS

Fibrinogen, D-dimer, F1+2, and TAT concentrations increased significantly throughout pregnancy, and were correlated with term of pregnancy. In our study, thrombin generation seemed to increase early on, and then remained stable throughout normal pregnancy, in contrast with other markers of blood coagulation activation, excepting FMC. The latter are subject to large inter-individual variations, especially during second trimester. No correlation was demonstrated between thrombin generation parameters and other activation markers.

CONCLUSION

While markers of coagulation activation significantly increased during pregnancy, thrombin generation increased only early on and remains stable during pregnancy. Finding a sensitive and specific biological marker for vascular pregnancy complications, such as FMC and thrombin generation levels, requires further investigation.

American Thoracic Society documents: an official American Thoracic Society/Society of Thoracic Radiology Clinical Practice Guideline--Evaluation of Suspected Pulmonary Embolism in Pregnancy

BACKGROUND

Pulmonary embolism (PE) is a leading cause of maternal mortality in the developed world. Along with appropriate prophylaxis and therapy, prevention of death from PE in pregnancy requires a high index of clinical suspicion followed by a timely and accurate diagnostic approach.

METHODS

To provide guidance on this important health issue, a multidisciplinary panel of major medical stakeholders was convened to develop evidence-based guidelines for evaluation of suspected pulmonary embolism in pregnancy using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system. In formulation of the recommended diagnostic algorithm, the important outcomes were defined to be diagnostic accuracy and diagnostic yield; the panel placed a high value on minimizing cumulative radiation dose when determining the recommended sequence of tests.

RESULTS

Overall, the quality of the underlying evidence for all recommendations was rated as very low or low with some of the evidence considered for recommendations extrapolated from studies of the general population. Despite the low quality evidence, strong recommendations were made for three specific scenarios: performance of chest radiography (CXR) as the first radiation-associated procedure; use of lung scintigraphy as the preferred test in the setting of a normal CXR; and performance of computed-tomographic pulmonary angiography (CTPA) rather than digital subtraction angiography (DSA) in a pregnant woman with a nondiagnostic ventilation-perfusion (V/Q) result.

DISCUSSION

The recommendations presented in this guideline are based upon the currently available evidence; availability of new clinical research data and development and dissemination of new technologies will necessitate a revision and update.

Magnetic resonance imaging and ultrasonography in diagnosis of pelvic vein thrombosis during pregnancy

INTRODUCTION

Pelvic deep vein thrombosis (DVT) is difficult to diagnose during pregnancy. In a two-center trial, we evaluated the agreement between ultrasonography and magnetic resonance imaging (MRI) in diagnosing the extent of DVT into the pelvic veins during pregnancy.

MATERIALS AND METHODS

Pregnant women with proximal DVT were examined both with ultrasound and MRI as part of a study designed for treatment of DVT during pregnancy. Ultrasound was performed using color flow by specialist in vascular ultrasound with Doppler and compression techniques. The MRI sequences consisted of a 2D Time of Flight angiography with arterial flow suppression and maximum intensity projection reconstructions; a 3D, T1-w-prepared gradient echo sequence with fat saturation for thrombus imaging; a steady-state free precession sequence; and a Turbo-Spin-Echo. No contrast agent was used. Proportion of agreement (kappa) for detection of DVT in individual veins was measured for different ipsilateral veins and inferior vena cava.

RESULTS

All 27 patients were imaged with both techniques at an average gestational age of 29 weeks (range 23-39). Three cases (11.5%) of DVT in the pelvic veins were missed on ultrasound but detected by MRI. The upper limit of the DVT was always depicted at a higher (20 cases, 65.4%) or the same level (seven cases, 34.6%) on MRI than on ultrasound. Agreement expressed as kappa was 0.33 (95% CI 0.27-0.40) demonstrating only fair agreement. In one woman the thrombus had propagated into the inferior vena cava, shown only on MRI.

CONCLUSION

Our study suggests that in pregnant women there is only fair agreement between ultrasound and MRI for determination of extent of DVT into pelvic veins, with MRI showing consistently more detailed depiction of extension. Our results indicate that MRI has an important role as a complementary technique in the diagnosis of DVT during pregnancy.