Pleural Effusion
Understanding Pleural Effusion found on Chest Computed Tomography imaging. Learn what this finding means and what steps to take next.
Radiographic Appearance
Computed Tomography FindingFluid collection in pleural space, appearing as dependent density
Clinical Significance
Indicates underlying disease; requires evaluation of cause
What is a Pleural Effusion?
Pleural effusion refers to an abnormal accumulation of fluid in the pleural space — the thin gap between the lung and the chest wall. Normally, this space contains only a small amount of lubricating fluid (＜ 15 mL).
Key Takeaway
Pleural effusion is not a disease itself, but a sign of an underlying condition affecting the heart, lungs, liver, or kidneys.
Imaging Appearance
On CT scan, pleural effusion typically appears as:
- Crescent-shaped fluid collection along the lung base
- Dependent layering — fluid settles in the lowest part of chest when upright
- Meniscus sign on chest X-ray
- Loss of costophrenic angle sharpness
CT is superior to X-ray for detecting small effusions and distinguishing fluid from other abnormalities.
Types of Pleural Effusion
Transudative Effusion
Caused by fluid leakage due to increased pressure or low protein:
- Heart failure (most common)
- Cirrhosis
- Kidney disease
- Pulmonary embolism
Lab characteristics:
- Low protein (＜ 3 g/dL)
- Low LDH
- Clear appearance
Exudative Effusion
Caused by inflammation or infection:
- Pneumonia (parapneumonic effusion)
- Cancer (lung, breast, lymphoma)
- Pulmonary embolism
- Tuberculosis
- Autoimmune disease (lupus, RA)
Lab characteristics:
- High protein (＞ 3 g/dL)
- High LDH
- May be cloudy or bloody
Symptoms
Depending on the amount of fluid:
- Shortness of breath (dyspnea)
- Sharp chest pain (pleuritic pain)
- Dry cough
- Difficulty breathing when lying flat
Small effusions may cause no symptoms.
Diagnosis
Your doctor may order:
1. Thoracentesis (Fluid Sampling):
- Needle inserted to remove and analyze fluid
- Determines if transudative vs. exudative
2. Pleural Fluid Analysis:
- Cell count (WBC, RBC)
- Protein, LDH, glucose
- Cytology (cancer cells)
- Culture (infection)
3. Imaging:
- Chest X-ray
- CT scan (best for small effusions)
- Ultrasound (guides procedures)
Treatment
Depends on the underlying cause:
Transudative:
- Treat heart failure (diuretics)
- Manage cirrhosis or kidney disease
Exudative:
- Antibiotics for infection
- Drainage for large effusions
- Chemotherapy for malignant effusion
Large or symptomatic effusions:
- Therapeutic thoracentesis (drain fluid)
- Chest tube placement
- Pleurodesis (prevent recurrence)
Important
Large effusions can compress the lung and impair breathing. Seek immediate medical attention if you have severe shortness of breath.
Prognosis
Outcomes depend on the cause:
- Heart failure effusions often improve with diuretics
- Infectious effusions usually resolve with antibiotics
- Malignant effusions indicate advanced cancer and may require palliative drainage
What Should You Do?
- Identify the cause - Work with your doctor to find the underlying condition
- Monitor symptoms - Track breathing difficulty, fever, chest pain
- Follow treatment plans - Take medications as prescribed
- Repeat imaging if recommended to ensure resolution
Related Imaging Terms
- Empyema - Infected pleural fluid (pus)
- Hemothorax - Blood in pleural space
- Atelectasis - Lung collapse often seen with effusion
Medical Disclaimer: This information is educational only. Pleural effusion requires professional medical evaluation and management.
Correlate with Lab Results
Doctors often check these blood tests when Pleural Effusion is found on imaging:
Related Imaging Terms
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