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Updated: Jun 11, 2025

Local Anesthetic Thoracoscopy for Undiagnosed Pleural Effusion
Published on: November 10, 2023
Aetiology of Pleural Effusions in a Large Multicentre Cohort: Variation Between Outpatients and Inpatients
Asfandyar Yousuf1, Sophie Holland2, Junyi Zhang3
1Department of Respiratory Medicine, Norfolk & Norwich University Hospital, Norwich, UK.
Introduction:
This multi-centre retrospective cohort study aimed to determine whether the cause of an undiagnosed pleural effusion differed depending on if a patient presented as an outpatient or inpatient.
Methods:
A total of 1080 adult patients (556 inpatients and 524 outpatients) presenting primarily with an undiagnosed pleural effusion from 1 January 2021 to 31 December 2022 from four UK hospitals were included.
Results:
We found malignant effusions were more common in outpatients compared to inpatients (48.3% vs. 36.0% p < 0.0001). Infection was common in inpatients but uncommon in outpatients (36.2% vs. 5.0% p < 0.0001). Other causes in all patients included heart and/or renal failure (13.1%) and non-specific pleuritis (5.6%). No diagnosis was possible in 11.8% of patients referred.
Conclusion:
Investigative pathways should vary depending on whether patients present as an inpatient or outpatient.
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