Investigation and diagnostic imaging of suspected pulmonary embolism during pregnancy and the puerperium: A review of the literature

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.

Pulmonary embolism diagnosis: clinical assessment at the front door

This first of two practice reviews addresses pulmonary embolism (PE) diagnosis considering important aspects of PE clinical presentation and comparing evidence-based PE testing strategies. A companion paper addresses the management of PE. Symptoms and signs of PE are varied, and emergency physicians frequently use testing to 'rule out' the diagnosis in people with respiratory or cardiovascular symptoms. The emergency clinician must balance the benefit of reassuring negative PE testing with the risks of iatrogenic harms from over investigation and overdiagnosis.

Diagnostic imaging for suspected pulmonary embolism during pregnancy and postpartum: A comparative radiation dose study

INTRODUCTION

To compare the radiation dose exposure and diagnostic efficiency of computed tomographic pulmonary angiography (CTPA) and ventilation/perfusion imaging (V/Q) for clinically suspected pulmonary embolism (PE) in pregnant and postpartum women in a tertiary hospital setting.

METHODS

A retrospective cohort study of 473 pregnant and postpartum women referred for CTPA or V/Q for clinically suspected PE between January 2013 and December 2018 at a tertiary hospital. Maternal effective radiation dose, breast-absorbed radiation dose and fetal-absorbed dose estimates were calculated. Diagnostic yield was evaluated from radiological findings.

RESULTS

Computed tomographic pulmonary angiography (CTPA) was more commonly used for the imaging of suspected PE in pregnant and postpartum populations (51.9% vs. 48.1% and 77.1% vs. 22.9%, respectively). CTPA was associated with higher maternal effective and breast-absorbed doses (maternal effective CTPA 4.7 (±2.9) mSv (millisievert), V/Q 1.7(±0.8) mSv (mean difference 2.93 mSv P < 0.001), and breast-absorbed CTPA 8.0 (±5.2) mGy (milligray), V/Q 0.3 (±0.1) (mean difference 7.67 mGy P < 0.001), respectively). Fetal radiation dose exposure was low. The incidence of positive PE was 5.5%. Indeterminate rates of CTPA and V/Q were 3.0% and 5.5% (P = 0.176), respectively.

CONCLUSIONS

Compared to V/Q, CTPA is associated with higher maternal and breast radiation dose; however, modern CT scanners achieve lower radiation doses than historically described. Fetal radiation dose was comparably low. The diagnostic yield of the imaging modalities in pregnant and postpartum women is similar. Revision of guidelines should occur with the advances in CT technology.

Investigation of fetal absorbed dose in V/Q scan in three trimesters of pregnancy using Monte Carlo simulation

The ventilation/perfusion (V/Q) single-photon emission computed tomography is the first method of diagnosis for pulmonary embolism in pregnant women. This study aimed to calculate the fetal absorbed dose and compare to recommended values in V/Q scan at three trimesters of pregnancy by Monte Carlo simulation (code MCNPX) using simulated phantoms, based on the adult female MIRD phantom. The collection of pregnant women phantoms (that of Stabin) was designed with changes in the MIRD phantom. Source organs were defined for each of the radiopharmaceuticals used in two scans, 133Xe and 81mKr for the lung and bladder and technetium diethylene-triamine-pentaacetate (99mTc-DTPA) aerosol for lung ventilation scan. Also, technetium macroaggregated albumin (99mTc-MAA) for lung ventilation scan, lung, bladder, and liver. Fetal absorbed dose was calculated and evaluated for the administration radiopharmaceuticals using the MCNP simulation output. For 200 MBq 99mTc-MAA, fetal absorbed dose was 1.01-1.97 mGy, which is higher than the values recommended by International Commission on Radiological Protection (ICRP). The same fetal absorbed dose was found for activities of 54 and 70 MBq in the third trimester. For 99mTc-DTPA-aerosol, fetal absorbed dose as a ventilation tracer was within the permitted range. For 133Xe and 81mKr, it was negligible. It is concluded that the fetus received the highest absorbed dose in the third trimester of pregnancy. For this reason, in this period of pregnancy, it is recommended to use the lower administration activity and her awareness must be done.

Update on pulmonary embolism in pregnancy and post-partum: The Society of Obstetric Medicine of Australia and New Zealand Position Statement on Pulmonary Embolism in Pregnancy and Post-partum

In this clinical review we highlight aspects of the diagnosis and management of pulmonary embolism (PE) in pregnancy and post-partum and how this may impact on antenatal and postnatal management. Investigation for PE in pregnancy is challenging and includes appropriate patient selection and knowledge of the risks and benefits of pulmonary imaging modalities. The complete Society of Obstetric Medicine of Australia and New Zealand Position Statement on Pulmonary Embolism in Pregnancy and Post-Partum comprehensively reviews all aspects of diagnosis, investigation and management and is accessible at https://www.somanz.org/guidelines.asp. It includes a summary of all recommendations and a guide to developing a management plan for birth in women on anticoagulation.

Imaging modalities for confirming pulmonary embolism during pregnancy: results from a multicenter international study

OBJECTIVES

We explored the variations in use of imaging modalities for confirming pulmonary embolism (PE) according to the trimester of pregnancy.

METHODS

We included all pregnant patients with confirmed acute PE from RIETE, a prospective registry of patients with PE (03/2001-02/2020). Imaging modalities included computed tomography pulmonary angiography (CTPA), ventilation-perfusion (V/Q) scan, or presence of signs of acute PE along with imaging-confirmed proximal deep vein thrombosis (pDVT) without pulmonary vascular imaging. We compared the imaging modalities to postpartum patients with PE, and other non-pregnant women with PE.

RESULTS

There were 157 pregnant patients (age: 32.7 ± 0.5), 228 postpartum patients (age: 33.9 ± 0.5), and 23,937 non-pregnant non-postpartum women (age: 69.5 ± 0.1). CTPA was the most common modality for confirming PE, from 55.7% in first trimester to 58.3% in second trimester, and 70.0% in third trimester. From first trimester to third trimester, V/Q scanning was used in 21.3%, 16.7%, and 18.3% of cases, respectively. Confirmed pDVT along with the presence of signs/symptoms of PE was the confirmatory modality for PE in 21.3% of patients in first trimester, 19.4% in second trimester, and 6.7% in third trimester. The proportion of postpartum patients confirmed with CTPA (85.5%) was comparable to that of non-pregnant non-postpartum women (83.2%). From the first trimester of pregnancy to postpartum period, there was a linear increase in the proportion of patients with PE diagnosed with CTPA (p = 0.039).

CONCLUSION

CTPA was the primary modality for confirming PE in all trimesters of pregnancy, although its proportional use was higher in later stages of pregnancy.

KEY POINTS

• Computed tomography pulmonary angiography (CTPA) was the primary modality of diagnosis in all trimesters of pregnancy among patients with confirmed pulmonary embolism, even in the first trimester. • From the first trimester of pregnancy to postpartum period, there was a linear increase in the proportion of patients with pulmonary embolism who were diagnosed based on CTPA. • In the postpartum period, use of CTPA as the modality to confirm pulmonary embolism was comparable to non-pregnant patients.