Ep 114 Pulmonary Embolism Challenges in Diagnosis 2 – Imaging, Pregnancy, Subsegmental PE

In Part 1 of Pulmonary Embolism Challenges in Diagnosis Drs. Helman, Lang and DeWit discussed a workup algorithm using PERC and Wells score, the bleeding risk of treated pulmonary embolism, pearls in decision making on whether or not to work up a patient for pulmonary embolism, how risk factors contribute to pretest probability, the YEARS criteria and age-adjusted D-dimer. In this Part 2 we answer questions such as: what are the important test characteristics of CTPA we need to understand? Which patients with subsegmental pulmonary embolism should we treat? When should we consider VQ SPECT? What is the best algorithm for the work up of pulmonary embolism in pregnant patients? How best should we implement pulmonary embolism diagnostic decision tools in your ED? and many more… Podcast production, sound design & editing by Anton Helman, additional editing by Sucheta Sinha Written Summary and blog post by Shaun Mehta & Alexander Hart, edited by Anton Helman August 2018 Cite this podcast as: Helman, A, Lang, E, DeWit, K. Pulmonary Embolism Challenges in Diagnosis 2 - Imaging, Pregnancy, Subsegmental PE. Emergency Medicine Cases. August, 2018. https://emergencymedicinecases.com/pulmonary-embolism-diagnosis-2-imaging-pregnancy-subsegmental-pe/. Accessed [date].   CTPA test characteristics and pulmonary embolism diagnosis As with the rest of emergency medicine, our interventions are rarely benign. In order to avoid unnecessary radiation and major bleeding complications as a result of anticoagulating patients with false positive CTPA results, it’s important to have a rational approach to imaging for PEs as well as a good approach to shared decision making with our colleagues, our radiologists and our patients. Although CTPA has become the gold standard for diagnosing PE and remains the best imaging modality available, it is far from perfect. The CTPA is prone to over-diagnosing clinically irrelevant emboli in low-risk patients [1]. Furthermore, although its sensitivity approaches 100% for clinically relevant PEs, in those with high pre-test possibility there is a small chance a clot might be missed. Those patients at high risk for PE based on a Wells score >6 with a negative CTPA should be counseled that although the present CTPA does not show a PE, up to 5% of high risk patients may develop a PE within a few months of a negative CTPA [2,3]. What about clot burden and location? These imaging characteristics have not been shown to accurately predict outcome, or even symptoms. The clinical context is much more important, and markers such as hypotension and hypoxia are better predictors of outcome [4]. Subsegmental pulmonary embolism: To treat or not to treat? In the last 10 years, the incidence of diagnosed PE has doubled, despite no change in mortality, partly due to advances in CT technology and partly due to radiologists overcalling subsegmental PEs due to medico-legal concerns. With modern CTs, subsegmental PEs are more often diagnosed. Although there is some variability in practice, most emergency physicians end up treating subsegmental PEs. But should we? An observational study by Goy et al. in 2015 reviewed 2213 patients with a diagnosis of subsegmental PE, and showed that whether or not anticoagulation was given, there were no recurrent PEs, yet 5% of anticoagulated patients developed life-threatening bleeding [5]. Other studies have yielded similar results [6]. Shared decision-making. Consider the patient’s bleeding risk (HASBLED score) and discuss potential treatment options.