Is pleural effusion (fluid buildup in the lungs) common in patients with COVID-19 (Coronavirus disease 2019), especially in those with severe disease or underlying health conditions?

Pleural Effusion in COVID-19: Prevalence and Clinical Significance

No, pleural effusion is not common in COVID-19 patients, occurring in only 5.3-5.8% of cases according to meta-analyses, though when present it indicates more severe disease with worse prognosis. 1

Prevalence and Characteristics

• Pleural effusion does not appear to be a prominent feature of COVID-19, with an overall incidence of 5.3-5.8% based on meta-analytic data 1
• When bilateral effusions do occur, they have been reported to resolve spontaneously in some cases 1
• Pleural effusion is scarcely observed even in severe cases with extensive lung parenchymal involvement 1
• One study found pleural effusion present in approximately 32% of hospitalized COVID-19 patients, though this represents a higher-risk population 1

Clinical Context and Risk Factors

Pleural effusion in COVID-19 typically indicates more severe disease and carries significant prognostic implications:

• Patients with pleural effusion demonstrate worse respiratory gas exchange (lower PaO2/FiO2 ratios), longer hospital stays, greater need for intensive care resources, and significantly higher mortality compared to those without effusion 2
• Pleural effusion is an independent negative prognostic factor even when controlling for other variables like elevated C-reactive protein, extent of pneumonia, and age 2
• Most pleural effusions (68%) are present at the initial CT scan rather than developing later in the disease course 2

Mechanisms of Effusion Development

When pleural effusion does occur in COVID-19, it typically results from:

• Bacterial superinfection in severe patients, leading to complicated parapneumonic effusions or empyema requiring targeted antimicrobial treatment 1
• Barotrauma in critically ill patients requiring invasive mechanical ventilation, which can lead to bronchopleural fistulae 1
• The systemic inflammatory response and coagulopathy associated with severe COVID-19 1

Clinical Management Approach

Diagnostic evaluation when effusion is present:

• Use bedside ultrasound to detect small pleural effusions and guide fluid collection if needed—it is widely available, safe, low-cost, and allows real-time assessment 1
• Perform pleural fluid aspiration and analysis when pleural infection is suspected to guide antimicrobial therapy 1
• Consider thoracentesis for symptomatic effusions or when malignancy is suspected in appropriate clinical contexts 1

Procedural precautions:

• Treat all pleural procedures as aerosol-generating procedures requiring Level 2 PPE (N95 respirator, face shield, gown, gloves) regardless of COVID-19 status 1, 3
• Perform procedures with trained, dedicated staff to minimize duration and complication risk 1
• Use negative pressure rooms when available 3

Important Clinical Pitfalls

• Do not assume pleural effusion is a typical COVID-19 finding—its presence should prompt evaluation for bacterial superinfection, heart failure, or other secondary complications 1
• Recognize that pleural effusion signals higher disease severity and warrants closer monitoring and potentially escalation of care 2
• In ventilated patients with new pleural effusion, consider barotrauma and bronchopleural fistula, particularly if pneumothorax is also present 1, 4
• Never clamp a bubbling chest drain in patients with air leak, as this may precipitate tension pneumothorax 3