The effectiveness of the pregnancy adapted YEARS algorithm to safely identify patients for CT pulmonary angiogram in pregnant and puerperal patients suspected of having pulmonary embolism

SA Journal of Radiology ISSN: (Online) 2078-6778, (Print) 1027-202X Page 1 of 6 Original Research The effectiveness of the pregnancy adapted YEARS algorithm to safely identify patients for CT pulmonary angiogram in pregnant and puerperal patients suspected of having pulmonary embolism Authors: Riaan Potgieter1 Piet Becker2 Farhana Suleman1 Affiliations: 1 Department of Diagnostic Radiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa Department of Statistics, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa 2 Corresponding author: Riaan Potgieter, Dates: Received: 15 Apr. 2022 Accepted: 31 May 2022 Published: 29 July 2022 How to cite this article: Potgieter R, Becker P, Suleman F. The effectiveness of the pregnancy adapted YEARS algorithm to safely identify patients for CT pulmonary angiogram in pregnant and puerperal patients suspected of having pulmonary embolism. S Afr J Rad. 2022;26(1), a2454. https://doi.org/10.4102/sajr. v26i1.2454 Copyright: © 2022. The Authors. Licensee: AOSIS. This work is licensed under the Creative Commons Attribution License. Read online: Scan this QR code with your smart phone or mobile device to read online. Background: Pulmonary thromboembolism is one of the leading causes of maternal death worldwide. Globally there has been increasing physician reliance on CT pulmonary angiogram for definitive diagnoses and exclusion of pulmonary thromboembolism. The problem, however, arises when considering the high radiation penalty from performing these investigations, highlighted by the low diagnostic yield. Of recent, the pregnancy-adapted YEARS algorithm has shown promise in international studies as a possible alternative for stratifying risk of pulmonary thromboembolism during the pregnancy and puerperal period. Objectives: To determine the effectiveness of the pregnancy adapted YEARS algorithm to safely minimise the number of true negative CT pulmonary angiograms for patients suspected of having pulmonary embolism in our clinical setting. Method: A cross-sectional study was performed in a tertiary hospital in Gauteng on puerperal and pregnant patients suspected of having pulmonary embolism. We retrospectively applied the pregnancy adapted YEARS algorithm and reviewed the various outcomes. Results: The pregnancy adapted YEARS algorithm proved effective in safely identifying patients for CT pulmonary angiography. By retrospectively applying the algorithm, there could have been a 25.7% scan reduction, whilst maintaining a negative predictive value of 100.0%. Conclusion: As physician reliance on radiological investigations increases, we must remain cognisant of the added radiation exposure and the long-term adverse effects of ionising radiation. The pregnancy-adapted YEARS algorithm provides a safe, reproducible alternative to aid our bid going forward. Keywords: pulmonary embolism; CT pulmonary angiogram; pregnancy-adapted YEARS algorithm; radiation safety; pregnancy; puerperium; persistent tachycardia; breast cancer. Introduction Pulmonary thromboembolism is a well-known complication during the pregnancy and puerperal periods.1 In the 2017 Saving Mothers Report, as well as in previous iterations, it is listed as one of the leading causes of maternal mortality in South Africa, causing roughly 30–40 maternal deaths per year.2 The physiological changes that take place during pregnancy render women especially vulnerable to this complication during their pregnancy and puerperal periods, with an estimated 5-fold increased risk when compared to age-related control groups.3 In addition, given the rising pandemic of obesity and increasing caesarean section rates in South Africa, both of which have been identified as independent risk factors, pulmonary thromboembolism in the South African context is a disease entity of justified concern.2,4,5 The clinical diagnosis of pulmonary thromboembolism is known to be challenging, given the fact that normal physiological changes that take place during pregnancy can mimic disease. Lower limb swelling, shortness of breath, and an increase in heart rate are all symptoms that can be experienced during the normal pregnancy and puerperal periods. Furthermore, established clinical criteria outside of pregnancy such as the Wells score, has to a large extent not been proven valid during the pregnancy and puerperal periods.6,7 Given this fact, there has been an increasing trend of clinicians relying on radiological methods to assist in diagnosing and/or excluding pulmonary thromboembolism and in the context of pregnancy, clinicians are over investigating suspected http://www.sajr.org.za Open Access Page 2 of 6 cases, with an exceptionally low diagnostic yield of 5% versus 15% – 20% in non-pregnant patients.8,9 CT pulmonary angiography is the investigation of choice in many institutions, including our own, for diagnosing pulmonary thromboembolism. It relies on contrasted imaging of the chest to opacify the pulmonary vasculature. In doing so, filling defects in the pulmonary arteries and associated complications of pulmonary thromboembolism can be detected. In addition, other unrelated pathologies (such as pneumonia or heart failure) that might explain the patient’s presenting symptoms can be diagnosed.10 There is however a trade-off in the form of radiation exposure to the patient. Foetal radiation exposure during CT imaging limited to the maternal chest is negligible, regardless of the use of radiation shielding.11 Uncertainty regarding the in-utero effects of iodinated contrast on the foetal thyroid gland has also not been correlated with significant postpartum sideeffects.12 A factor for concern however is radiation exposure to gravid breast tissue, where it is estimated that a single CT pulmonary angiogram study increases a woman’s lifetime risk of developing breast cancer by 13.6%.1,11 This is a distressing figure given the fact that breast cancer is the most common cancer in women, with an increasing incidence worldwide.13 The use of bismuth breast shields and limited radiological techniques has been proven effective in lowering radiation dose to the female breast, although not a common practise in our institution.14 Ventilation/perfusion (V/Q) scans offer a more than 10 fold reduction in breast radiation dose in addition to mitigating the risk of adverse reactions from iodinated intravenous contrast.11 Unfortunately V/Q scans are underutilised at our institution given its unavailability in the after-hours setting. From the aforementioned information, it is evident that there is a need for a diagnostic protocol that balances the urgency of the disease with the potential adverse effects of radiation exposure. It should also consider the physiological changes and disease mimics in pregnancy. The YEARS study was conducted in 2015-2016, and is currently under scrutiny by the international community as a proposed alternative algorithm for risk stratificatio (...truncated)