Missed Diagnosis of Pulmonary Embolism in Patients Presenting with Acute Exacerbation of COPD: A Systematic Review

Background: Pulmonary embolism presents with symptoms that overlap with acute exacerbation of chronic obstructive pulmonary disease, creating uncertainty about its frequency and initial recognition during routine assessment. This review examined prevalence, unsuspected disease, and associated clinical features. Methods: Original studies published through 31 May 2026 were examined using a framework that separated systematically detected embolism, initially unsuspected embolism, and diagnoses established after the initial assessment. Findings were synthesized narratively because recruitment criteria, diagnostic pathways, and outcome definitions differed. Results: We included eleven primary studies and three secondary analyses. Pulmonary embolism prevalence ranged from 3.3% to 29.1% in prospective investigations, while a large emergency department database recorded diagnosed embolism in 0.56% of presentations. In patients without initial clinical suspicion, individual studies reported embolism in 1.3% and 4.6%, respectively. Associated features included previous venous thromboembolism, malignancy, reduced arterial carbon dioxide, absent infectious symptoms, obesity, lower limb asymmetry, and tachypnoea. Several associations originated from small samples, and subsequent prediction models showed limited discrimination or required further prospective evaluation. Routine active investigation did not improve the primary composite clinical outcome in the randomised trial. Conclusion: Pulmonary embolism represents an established alternative or accompanying diagnosis during COPD exacerbations, mainly in selected unexplained presentations. Available data support careful risk assessment without equating screening prevalence with the prevalence of missed diagnosis.