Noninvasive diagnostic work-up for suspected acute pulmonary embolism during pregnancy: a systematic review and meta-analysis of individual patient data

Consent to advanced imaging in antenatal pulmonary embolism diagnostics: Prevalence, outcomes of nonconsent and opportunities to mitigate delayed diagnosis risk

BACKGROUND

Nonconsent to pulmonary vascular (or advanced) imaging for suspected pulmonary embolism (PE) in pregnancy can delay diagnosis and treatment, increasing risk of adverse outcomes. We sought to understand factors associated with consent and understand outcomes after nonconsent.

METHODS

This retrospective cohort study was undertaken across 21 community hospitals from October 1, 2021, through March 31, 2023. We included gravid patients undergoing diagnostics for suspected PE who were recommended advanced imaging. The primary outcome was verbal consent to advanced imaging. Diagnostic settings were nonobstetric (99% emergency departments [EDs]) and obstetrics (labor and delivery and outpatient clinics). Using quasi-Poisson regression, we calculated adjusted relative risks (aRRs) of consenting with 95% confidence intervals (CIs). We also reported symptom resolution and delayed imaging at follow-up and 90-day PE outcomes.

RESULTS

Imaging was recommended for 405 outpatients: median age was 30.5 years; 50% were in the third trimester. Evaluation was more common in nonobstetric (83%) than obstetric settings (17%). Overall, 314 (78%) agreed to imaging and 91 (22%) declined imaging. Consenting was more prevalent in obstetric settings compared with nonobstetric settings: 99% versus 73% (p < 0.001). When adjusted for demographic and clinical variables, including pretest probability, only obstetric setting was independently associated with consenting: aRR 1.26 (95% CI 1.09-1.44). Seventy-nine (87%) patients declining imaging had 30-day follow-up. Eight of 12 who reported persistent or worsening symptoms on follow-up were again recommended advanced imaging and consented. Imaging was negative. None who initially declined imaging were diagnosed with PE or died within 90 days.

CONCLUSIONS

One in five gravid patients suspected of PE declined advanced imaging, more commonly in nonobstetric (principally ED) settings than obstetric settings. Patients symptomatic on follow-up responded favorably to subsequent imaging recommendations without 90-day outcomes. Improving the communication and documentation of informed consent and securing close follow-up for nonconsenters may mitigate risks of missed and delayed PE diagnosis.

Diagnostic management of acute pulmonary embolism

Straightforward, accurate diagnostic management in patients presenting with clinically suspected pulmonary embolism (PE) is essential, since starting anticoagulant treatment may give important adverse effects of bleeding, while false exclusion of the disease may lead to recurrent VTE, with associated morbidity and mortality. In the past three decades, considerable improvement in the diagnostic management of PE has been made. Computed tomography pulmonary angiography (CTPA) has largely replaced conventional pulmonary angiography and ventilation-perfusion lung scanning as the imaging methods of choice. Several diagnostic algorithms, all able to minimize the need for radiological imaging have been developed and validated. Lastly, within the diagnostic algorithms, varying d-dimer cut-off levels have successfully been introduced to further downsize the need for radiological imaging.

Prognostic Value of Neutrophil/Lymphocyte Ratio for Pulmonary Embolism: A Meta-Analysis and External Validation

BACKGROUND

Prognostic value of neutrophil/lymphocyte ratio (NLR) for pulmonary embolism (PE) has been reported in several retrospective studies. The purpose of this investigation was to perform a pooled analysis and external validation of predictive value of NLR.

METHODS

PubMed, Embase, and Cochrane databases were searched from inception to November 5, 2022. A random effects model was used. Grade was used to evaluate the certainty of evidence. External validation was conducted in clinical cohorts before and after a propensity scoring matching (PSM). Covariates include basic clinical characteristics, such as age, gender, etc. The value of NLR in prediction model was also evaluated.

RESULTS

A total of 15 studies comprising 5,874 patients were included. Pooled risk ratio of NLR was 2.33 (95% confidence interval [CI]: 1.97-2.75), with an area under the curve of 0.78 (95% CI: 0.74-0.81), a sensitivity of 0.75 (95% CI: 0.71-0.79), a specificity of 0.67 (95% CI: 0.61-0.73), and a median cut-off value of 5.7. Grade of Recommendations Assessment Development and Evaluation (GRADE) certainty analysis showed the quality of the evidence was moderate. Before (n = 336) and after (n = 152) propensity scoring matching, risk ratio of NLR was 2.69 (95% CI: 1.04-6.97) and 6.58 (95% CI: 1.99-17.75). A prediction model consisting of NLR, age, D-dimer, and simplified PE severity index had an area under the curve of 0.809 (95% CI: 0.738-0.88), a sensitivity of 0.638 (95% CI: 0.511-0.745), and a specificity of 0.851 (95% CI: 0.709-0.917). Net reclassification index (12%, P = 0.035) and integrated discrimination improvement (17%, P = 0.022) indicated an improvement caused by NLR.

CONCLUSIONS

Prognostic value of NLR for PE was confirmed by meta-analysis and validated in an independent cohort, deserving further clinical application.

The History of Diagnosing Venous Thromboembolism

An accurate and prompt diagnosis of deep vein thrombosis and/or pulmonary embolism is important to prevent serious complications and mortality. Because the clinical presentation of venous thromboembolism (VTE) is often nonspecific, objective testing by means of radiological imaging is required to confirm the diagnosis. Historically, a diagnosis of VTE involved invasive imaging techniques like contrast venography or conventional pulmonary angiography. Technological developments toward more accurate and less invasive diagnostics have driven the implementation of a variety of newer technologies over the past decades, as well as the derivation and validation of clinical decision rules (CDRs) that can be used to rule out VTE in combination with D-dimer blood tests. In this narrative review, we provide a historical overview of the most notable developments in the imaging techniques and CDRs for VTE diagnosis.

Modern imaging of acute pulmonary embolism

The first-choice imaging test for visualization of thromboemboli in the pulmonary vasculature in patients with suspected acute pulmonary embolism (PE) is multidetector computed tomography pulmonary angiography (CTPA) - a readily available and widely used imaging technique. Through technological advancements over the past years, alternative imaging techniques for the diagnosis of PE have become available, whilst others are still under investigation. In particular, the evolution of artificial intelligence (AI) is expected to enable further innovation in diagnostic management of PE. In this narrative review, current CTPA techniques and the emerging technology photon-counting CT (PCCT), as well as other modern imaging techniques of acute PE are discussed, including CTPA with iodine maps based on subtraction or dual-energy acquisition, single-photon emission CT (SPECT), magnetic resonance angiography (MRA), and magnetic resonance direct thrombus imaging (MRDTI). Furthermore, potential applications of AI are discussed.

Pulmonary Embolism in Pregnancy: A Review for Clinical Practitioners

Diagnostic and therapeutic decision-making in pregnancy with suspected pulmonary embolism (PE) is challenging. European and other international professional societies have proposed various recommendations that are ambiguous, probably due to the unavailability of randomized controlled trials. In the following sections, we discuss the supporting diagnostic steps and treatments. We suggest a standardized diagnostic work-up in pregnant patients presenting with symptoms of PE to make evidence-based diagnostic and therapeutic decisions. We strongly recommend that clinical decisions on treatment in pregnant patients with intermediate- or high-risk pulmonary embolism should include a multidisciplinary team approach involving emergency physicians, pulmonologists, angiologist, cardiologists, thoracic and/or cardiovascular surgeons, radiologists, and obstetricians to choose a tailored management option including an interventional treatment. It is important to be aware of the differences among guidelines and to assess each case individually, considering the specific views of the different specialties. This review summarizes key concepts of the diagnostics and acute management of pregnant women with suspected PE that are supportive for the clinician on duty.

VTE risk assessment, prevention and diagnosis in pregnancy

Venous thromboembolism (VTE) is still reported as the leading cause of direct maternal death in pregnancy in serial international reports in developed countries. VTE risk is higher during pregnancy but is further increased by additional well-characterized risk factors. International guidelines recommend that formal VTE risk assessment should be conducted at least in early pregnancy, at delivery and when risk factors change. High quality data supporting optimal VTE prevention strategies are lacking, outside the setting of prevention of VTE recurrence. Moreover, recent high-quality studies have provided much-needed data on diagnostic strategies for pulmonary embolism (PE) in pregnancy. In this review, we summarize knowledge gaps and recently published data in the prevention and diagnosis of VTE in pregnancy. Moreover, we describe ongoing high-quality randomised trials and prospective clinical management studies in this area. High quality clinical studies and trials in pregnancy can be done and must be prioritised, through international network efforts and national funding advocacy. Ultimately, translation of study results to impact upon guidelines and policy will deliver better care to and will protect the lives and health of pregnant people and those contemplating pregnancy throughout the world.

Prevention, diagnosis, and management of PE and DVT in pregnant women

Venous thromboembolism (VTE) is a leading cause of maternal morbidity and mortality worldwide. Despite the impact of VTE on pregnant and postpartum people and on society, guidelines addressing prevention, diagnosis, and management of VTE in pregnant and postpartum people frequently are based on recommendations from expert opinion and are extrapolated from data in nonpregnant populations. Pregnant individuals are frequently excluded from clinical trials, which is a barrier to providing safe, effective care. Anchoring to a case discussion, this review provides an update on recently published and ongoing randomized clinical trials (RCTs), prospective clinical management studies, and other research in this area. It highlights, in particular, the results of the Highlow RCT, which addresses optimal prevention of recurrence during pregnancy in people with prior VTE. Finally, we raise awareness of the impact of national and international clinical trial networks on the conduct of RCTs in pregnancy. We conclude, based on these data, that academic VTE clinical trials in pregnant women can and must be done.

Excluding pregnancy-associated deep vein thrombosis with whole-leg ultrasound

Background

Deep vein thrombosis (DVT) is common in pregnancy, yet data are limited on the best diagnostic strategies in pregnant patients suspected of DVT.

Objectives

We conducted a prospective cohort study to evaluate the rate of symptomatic DVT in the 90 days after a negative whole-leg compression ultrasound (CUS) in pregnant women presenting with DVT symptoms.

Methods

In this prospective cohort study, we enrolled pregnant patients suspected of DVT between 2011 and 2019 who were referred to the vascular imaging laboratory at a tertiary care center and had anticoagulation held after a negative whole-leg CUS. Primary outcome was objectively confirmed DVT or pulmonary embolism or death due to venous thromboembolism (VTE).

Results

Whole-leg CUS yielded normal results in 186 patients (97.9%) and identified DVT in 4 (2.1%). The mean age was 30 and 164 were White. Among the 186 patients with a negative, initial whole-leg CUS who did not receive anticoagulation, there were 2 DVT events identified over the 90-day follow-up period, for an overall rate of 1.1% (95% CI: 0.2-3.4%). The study was terminated before full planned accrual for administrative reasons.

Conclusion

The rate of symptomatic DVT is low in pregnant patients who have a single, negative whole-leg CUS and did not receive anticoagulation. Adequately powered studies should prospectively assess whole-leg CUS in a larger population alone and in combination with pre-test probability scores and/or D-dimer to determine its role in the evaluation of suspected DVT in pregnancy.