The leading cause of non-obstetric maternal mortality is pulmonary embolism (PE), accounting for 10% of maternal deaths in developed countries (Easther, Langdana, Maharaj, Abels, Beasley, & Entwisle, 2016.) Pregnant women have historically been excluded from studies investigating evidenced based modalities for PE diagnosis. In their 2010-2012 cohort data analysis of 54 ante/postnatal Wellington Hospital (located in New Zealand) obstetric patient records, Easther et al. (2016) sought to determine the best practice for identifying PE via ventilation/perfusion (V/Q) imaging or computed topography pulmonary angiography (CTPA). This topic of research is vital to improving maternal healthcare as current practice standards do not take into account the unique physiology of ante/postnatal patients including, alterations in plasma volume, cardiac output, and body compartment fluid distribution. These changes negatively affect the accuracy of CTPA (Easther, et al., 2016.) Concerns about maternal and fetal exposure to radiation also contribute to the need for specific guidelines of CTPA use.
Although this was a small study, the researchers developed a clinical pathway for PE investigation. Following clinical suspicion of PE during pregnancy or postpartum, the clinical should take a full history, complete a physical examination, and assess for risk factors. If there is a likelihood of PE and concurrent clinical signs and symptoms a chest X-ray should be performed to rule out other pathologies (e.g. pneumonia). Once other pathologies are ruled out, V/Q scan using low dose perfusion contrast is indicated for 2nd and 3rd trimesters and during the postpartum period; CTPA is indicated in the first trimester, if massive PE is suspected, or if the chest x-ray was abnormal as this causes a V/Q scan to be indeterminate (Easther, et al., 2016.) The researchers took into account the improved accuracy of V/Q scan in pregnant women, the radiation exposure of both modalities to the fetus, mother, and breast tissue, and family history of breast cancer when developing this clinical pathway.
This study and its results present a guide for developing a best practice based on evidence to improve the recognition of life-threatening PE in ante/postnatal women. Further research into this topic is needed, with larger sample sizes in order for it to translate into practice.
Easther, S., Langdana, F., Maharaj, D., Abels, P., Beasley, R., & Entwisle, J. (2016). The diagnostic role of ventilation/perfusion scans versus computed tomography pulmonary angiography in obstetric patients investigated for pulmonary embolism at Wellington Hospital from 2010 to 2012. The New Zealand Medical Journal, 129(1433). Retrieved from https://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2016/vol-129-no-1433-22-april-2016/6869