🏥 Stations

🧠 Qbank

📖 Book

😃 More

💳 Pricing

🔒 Dashboard

📖 OSCE Learning

🔒 OSCE Stations

🔒 Qbank

🔐 Membership
Share your insights

Help us by sharing what content you've recieved in your exams


Pleural effusion

Medicine > Infection

Differential Diagnosis Schema 🧠

Transudative Causes

  • Heart failure: Most common cause; associated with bilateral, typically transudative effusions.
  • Cirrhosis: Hepatic hydrothorax due to portal hypertension; often right-sided.
  • Nephrotic syndrome: Hypoalbuminemia leads to decreased oncotic pressure and transudative effusions.
  • Hypoalbuminemia: Various causes (e.g., malnutrition, liver disease) leading to transudative effusions.
  • Constrictive pericarditis: Causes elevated venous pressures, leading to transudative pleural effusion.
  • Pulmonary embolism: Can cause both transudative and exudative effusions; often associated with pleuritic chest pain.
  • Myxedema: Severe hypothyroidism can cause pleural effusion, typically transudative.

Exudative Causes

  • Pneumonia (parapneumonic effusion): Common cause of exudative effusion; associated with fever, productive cough.
  • Malignancy: Pleural metastases from lung, breast, or other cancers can cause exudative effusions, often bloody.
  • Tuberculosis: Chronic infection leading to lymphocyte-predominant exudative effusion.
  • Rheumatoid arthritis: Can cause rheumatoid pleuritis, leading to an exudative effusion; associated with joint pain and stiffness.
  • Systemic lupus erythematosus (SLE): Exudative effusion, often with other serositis (pericarditis, peritonitis) in SLE patients.
  • Empyema: Collection of pus in the pleural space, usually secondary to infection; exudative effusion with low pH and glucose.
  • Pancreatitis: Causes exudative effusion, usually left-sided, associated with high pleural fluid amylase.
  • Oesophageal rupture (Boerhaave syndrome): Severe chest pain and vomiting; causes exudative effusion with high amylase.
  • Chylothorax: Accumulation of lymphatic fluid due to thoracic duct injury; exudative effusion with high triglycerides.

Key Points in History 🥼

Symptom Onset and Duration

  • Acute onset: Suggests causes like pulmonary embolism, trauma, or oesophageal rupture.
  • Subacute or chronic onset: More consistent with heart failure, malignancy, or tuberculosis.
  • Intermittent symptoms: May indicate a chronic or recurrent condition, such as rheumatoid arthritis or malignancy.
  • Rapidly progressive symptoms: Consider malignancy or empyema.

Associated Symptoms

  • Dyspnoea: Common in all causes of pleural effusion, particularly large effusions or those associated with heart failure.
  • Chest pain: Pleuritic pain suggests infection or pulmonary embolism; dull pain may indicate malignancy.
  • Cough: Often seen in parapneumonic effusions, heart failure, and malignancy.
  • Fever: Suggests an infectious cause, such as pneumonia or empyema.
  • Weight loss: Concerning for malignancy or chronic infection like tuberculosis.
  • Night sweats: Associated with tuberculosis and malignancy.
  • Haemoptysis: Raises suspicion for pulmonary embolism, malignancy, or tuberculosis.
  • Orthopnoea and paroxysmal nocturnal dyspnoea: Suggest heart failure as a cause of pleural effusion.
  • Arthralgia: Associated with systemic lupus erythematosus or rheumatoid arthritis.
  • Abdominal pain: Consider pancreatitis, especially if the effusion is left-sided.
  • History of trauma: Important in assessing for haemothorax or oesophageal rupture.
  • Recent surgery: Raises the possibility of postoperative complications like chylothorax.

Background

  • Past medical history: Includes history of heart failure, chronic liver disease, malignancy, or autoimmune disorders.
  • Medication history: Review use of drugs that can cause pleural effusion, such as amiodarone, methotrexate, or certain chemotherapy agents.
  • Family history: Consider familial predispositions to conditions like autoimmune diseases or malignancies.
  • Social history: Includes smoking, alcohol use, occupational exposures, and travel history.
  • Exposure history: Includes exposure to asbestos, which is a risk factor for malignant mesothelioma.
  • Immunisation history: Particularly relevant for preventing infections that can lead to parapneumonic effusions.
  • Recent infections: History of respiratory infections can predispose to parapneumonic effusion or empyema.
  • Surgical history: Relevant for assessing postoperative complications like chylothorax or haemothorax.
  • Occupational history: Important for assessing risk factors like asbestos exposure.

Possible Investigations 🌡️

Imaging

  • Chest X-ray: Initial imaging modality; look for blunting of the costophrenic angle, meniscus sign, and mediastinal shift if large.
  • Ultrasound: Useful for detecting and characterising pleural effusions, guiding thoracentesis, and assessing for septations or loculations.
  • CT scan: Provides detailed assessment of pleura and underlying lung; useful in detecting malignancy, pulmonary embolism, or empyema.
  • MRI: Less commonly used but can be helpful in differentiating between benign and malignant pleural thickening.
  • Echocardiography: Indicated if heart failure or pericardial disease is suspected as a cause of pleural effusion.
  • Ventilation-perfusion (V/Q) scan: Useful in diagnosing pulmonary embolism if CT is contraindicated.
  • PET scan: Useful in staging malignancy or assessing pleural involvement in cancer.

Laboratory Tests

  • Pleural fluid analysis: Gold standard; includes Light’s criteria to differentiate transudate vs. exudate, and tests for protein, LDH, glucose, pH, and cell count.
  • Pleural fluid culture and Gram stain: To identify infectious organisms in suspected parapneumonic effusion or empyema.
  • Cytology: Essential in suspected malignant effusion to detect cancer cells in pleural fluid.
  • Pleural fluid triglycerides: Elevated in chylothorax, particularly in traumatic or malignant causes.
  • Pleural fluid amylase: Elevated in oesophageal rupture or pancreatitis-related effusion.
  • Full blood count (FBC): To assess for infection, anaemia, or other systemic causes.
  • Renal function tests (U&E): Important in assessing for nephrotic syndrome or renal failure as a cause.
  • Liver function tests: To assess for liver disease in suspected hepatic hydrothorax or cirrhosis-related effusion.
  • Tuberculin skin test or IGRA: To assess for tuberculosis in chronic or unexplained effusions.
  • Autoimmune screen (ANA, RF, anti-CCP): To assess for autoimmune causes like SLE or rheumatoid arthritis.
  • NT-proBNP: Elevated in heart failure, helping to differentiate from other causes of effusion.
  • Blood glucose and protein levels: Low in conditions like nephrotic syndrome or severe malnutrition.
  • HIV test: Consider in cases of unexplained effusion, particularly in younger patients or those with risk factors.
  • Serum amylase and lipase: Elevated in pancreatitis, which may cause pleural effusion.
  • Arterial blood gases (ABG): To assess oxygenation and acid-base status in patients with significant respiratory symptoms.
  • Sputum culture and cytology: Consider if there is an underlying lung infection or suspected malignancy.
  • Coagulation profile: To assess for bleeding risk before procedures like thoracentesis.
  • Serum lactate dehydrogenase (LDH): Elevated in exudative effusions, particularly in malignancy or infection.
  • Serum albumin: Helps differentiate transudative from exudative effusions using the serum-to-pleural fluid albumin gradient.

No comments yet 😉

Leave a Reply

Infection