Pleural effusion:Causes,Types,Symptoms and Treatment

Pleural effusion, which is the abnormal accumulation of fluid in the pleural cavity, can be caused by a variety of diseases and conditions.

Here are some of the most common causes:

  1. Congestive Heart Failure (CHF): When the heart is unable to pump effectively, blood can back up into the lungs, leading to increased pressure within the blood vessels. This increased pressure can cause fluid to leak into the pleural space.
  2. Pneumonia: Infections of the lung, such as bacterial, viral, or fungal pneumonia, can cause inflammation of the pleural membrane, leading to an accumulation of fluid.
  3. Lung Cancer: Cancer cells can invade the pleural space, causing an inflammatory response that leads to fluid accumulation. Lung cancer can also obstruct the lymphatic system, which can result in fluid buildup.
  4. Cirrhosis and Liver Disease: Portal hypertension, which is often a result of liver disease, can lead to increased pressure in the abdomen and chest. This pressure can push fluid into the pleural cavity.
  5. Kidney Disease: When the kidneys are not functioning properly, they may not be able to remove excess fluid from the body, leading to fluid overload and pleural effusion.
  6. Pleural Effusion Due to Infections: Tuberculosis, as well as other infections, can directly affect the pleura and lead to an exudative effusion.
  7. Autoimmune Diseases: Conditions like systemic lupus erythematosus (SLE) and rheumatoid arthritis can cause inflammation of the pleura, leading to an accumulation of fluid.
  8. Pleural Effusion Due to Drug Reactions: Certain medications, such as some anti-inflammatory drugs, can lead to pleural effusion as a side effect.
  9. Pulmonary Embolism: Blood clots in the lungs can cause inflammation and increased pressure, which can result in pleural effusion.
  10. Postoperative Complications: After certain chest or abdominal surgeries, patients may develop pleural effusion due to inflammation or infection.
  11. Chylothorax: This is a type of pleural effusion that results from the leakage of lymphatic fluid into the pleural space, often due to trauma or surgery that disrupts the lymphatic system.
  12. Pleural Effusion Due to Metabolic Disorders: Conditions like hypoalbuminemia, where there is a low level of albumin in the blood, can lead to fluid leakage into the pleural space.
  13. Pleural Effusion Due to Other Cancers: cancers that metastasize to the pleura, such as breast, ovarian, and pancreatic cancer, can also cause pleural effusion.
pleural effusion can be caused by a variety of diseases and conditions
pleural effusion can be caused by a variety of diseases and conditions

Pleural effusions can be classified into several types based on their composition and the underlying causes.

Here are the main types of pleural effusions and their common causes:

  1. Transudative Pleural Effusion: This type of effusion is caused by systemic factors that alter the pressure within blood vessels and pleural spaces, leading to fluid leakage into the pleural cavity. Common causes include:
    • Congestive heart failure
    • Liver cirrhosis with portal hypertension
    • Nephrotic syndrome
    • Hypoproteinemia (low blood protein levels)
  2. Exudative Pleural Effusion: Exudative effusions are characterized by an increased permeability of blood vessels, often due to inflammation or infection. The fluid in these effusions has a higher protein content than transudative effusions. Common causes include:
    • Pneumonia
    • Tuberculosis
    • Lung cancer
    • Other cancers that have metastasized to the pleura
    • Autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis)
    • Pancreatitis
    • Sepsis
  3. Chylous (Lymphatic) Pleural Effusion: This type of effusion occurs when lymphatic fluid leaks into the pleural space, often due to obstruction or damage to the lymphatic system. Common causes include:
    • Surgery or trauma that injures lymphatic vessels
    • Cancer that obstructs lymphatic flow
    • Congenital lymphatic system disorders
    • Certain infections, such as tuberculosis
  4. Hemorrhagic Pleural Effusion: Hemorrhagic effusions are characterized by the presence of blood in the pleural fluid, which can be red or brownish in color. Causes include:
    • Trauma
    • Pulmonary embolism
    • Tumor invasion of blood vessels
    • Other causes of bleeding disorders
  5. Malignant Pleural Effusion: This type of effusion is caused by cancer cells invading the pleura. It is exudative in nature and can be due to:
    • Lung cancer
    • Breast cancer
    • Ovarian cancer
    • Lymphoma
    • Other cancers that metastasize to the pleura
  6. Parapneumonic Pleural Effusion: This effusion occurs in association with pneumonia and can be either transudative or exudative. If left untreated, it can progress to empyema, a more serious condition involving pus in the pleural space.
  7. Urinothorax: This rare type of effusion occurs when urine leaks into the pleural space, usually due to a fistula between the urinary tract and the pleural cavity. It can be caused by:
    • Urological procedures
    • Renal pelvic or ureteral injuries
    • Malignant tumors invading the urinary tract
main types of pleural effusions
main types of pleural effusions

what is loculated pleural effusion?

Loculated pleural effusion refers to a condition where the accumulated fluid in the pleural space is divided into separate compartments by fibrous septa or adhesions. These divisions create distinct pockets of fluid that are not freely communicating with each other. The loculation can occur as a result of inflammation, infection, scarring from previous surgeries, or tumor invasion within the pleural space.

The presence of loculations can make the drainage of the pleural effusion more challenging, as each compartment may need to be accessed and drained individually. Diagnosis often involves imaging studies such as ultrasound or CT scans to visualize the extent and location of the loculated fluid. Treatment may include thoracentesis, where a needle is used to drain the fluid, or more invasive procedures like thoracoscopic surgery or video-assisted thoracoscopic surgery (VATS) to remove the septations and allow for complete drainage of the fluid. In some cases, if the loculated effusion is due to an infection, antibiotics or other appropriate medications may be administered.

loculated pleural effusion
loculated pleural effusion

what is malignant pleural effusion?

Malignant pleural effusion refers to the accumulation of fluid in the pleural cavity that is caused by cancer. It occurs when cancer cells invade the pleura, the membrane that lines the chest cavity and surrounds the lungs. This invasion can lead to inflammation and increased permeability of the pleural membrane, allowing fluid to leak into the pleural space.

Malignant pleural effusions are often a sign of advanced cancer and can be associated with symptoms such as shortness of breath, cough, and chest pain. The most common cancers that lead to malignant pleural effusion include lung cancer, breast cancer, ovarian cancer, and lymphoma, although other cancers can also metastasize to the pleura and cause this condition.

Diagnosis typically involves analyzing the pleural fluid for the presence of cancer cells, as well as imaging studies to assess the extent of the effusion and to look for tumor deposits. Treatment options for malignant pleural effusion include drainage of the fluid to relieve symptoms (thoracentesis), pleurodesis (a procedure to seal the pleural space and prevent the reaccumulation of fluid), and chemotherapy or other systemic treatments aimed at controlling the underlying cancer. In some cases, palliative care is focused on managing symptoms and improving quality of life.

The Deutsches Krebsforschungszentrum(DKFZ) has developed advanced imaging technologies such as PET-CT for more accurate diagnosis and monitoring of MPE; researched the application of nanomedicines in the treatment of MPE, and found that nanomedicines can target tumor cells more effectively.


Pleural effusion, the abnormal accumulation of fluid in the pleural cavity, can cause a variety of symptoms, which may include:

  1. Dyspnea (Shortness of Breath): This is the most common symptom of pleural effusion. As fluid builds up, it can compress the lung, making it harder to breathe.
  2. Chest Pain: Pressure from the fluid can cause chest discomfort or pain, which may worsen with deep breathing, coughing, or laughing.
  3. Cough: The presence of fluid can irritate the pleura and lead to a persistent cough.
  4. Weakness or Fatigue: The extra effort required to breathe due to the pleural effusion can lead to generalized weakness and fatigue.
  5. Wheezing or Crackles: Depending on the underlying cause, there may be abnormal lung sounds such as wheezing or crackles when listening with a stethoscope.
  6. Fever: If the pleural effusion is due to an infection, such as pneumonia or tuberculosis, fever may be present.
  7. Weight Loss: In the context of malignant pleural effusion, unexplained weight loss can be a symptom.
  8. Loss of Appetite: This can be associated with the general feeling of malaise that comes with having a pleural effusion.
  9. Dizziness or Lightheadedness: In severe cases, the reduced oxygen exchange due to the compressed lung can lead to symptoms of hypoxia, including dizziness or lightheadedness.
  10. Hypoxemia: Low levels of oxygen in the blood can lead to symptoms such as confusion, restlessness, or, in severe cases, cyanosis (bluish discoloration of the skin).

The specific symptoms experienced by an individual can vary depending on the underlying cause of the pleural effusion, the rate at which the fluid accumulates, and the overall health status of the patient. If symptoms suggestive of pleural effusion are present, medical attention should be sought for proper diagnosis and treatment.


The treatment of pleural effusion depends on the underlying cause, the size of the effusion, the symptoms it produces, and whether the effusion is exudative (due to inflammation or infection) or transudative (due to fluid leakage from increased pressure, such as in heart failure). Here are some common treatment approaches:

  1. Thoracentesis: This is the most common initial treatment for pleural effusion. It involves the insertion of a needle or catheter into the pleural space to drain the fluid. Thoracentesis can provide immediate relief of symptoms and can also help in diagnosing the cause of the effusion by analyzing the drained fluid.
  2. Pleurodesis: For effusions that recur frequently, pleurodesis may be performed. This procedure involves instilling a talc or other sclerosing agent into the pleural space to create inflammation and adhesion between the parietal and visceral pleura, sealing them together and preventing the reaccumulation of fluid.
  3. Tube Thoracostomy (Chest Tube): If a large volume of fluid needs to be drained or if the effusion recurs, a chest tube may be inserted to continuously drain the fluid. This is often done in cases of large effusions, empyema (pus in the pleural space), or when pleurodesis is planned.
  4. Chemotherapy and Targeted Therapies: In the case of malignant pleural effusion, systemic treatments such as chemotherapy or targeted therapies may be used to shrink the tumor and slow the production of fluid.
  5. Radiation Therapy: Directed at tumor sites in the pleura, radiation therapy can be used to reduce the size of tumors and control the effusion in some cases of malignant pleural effusion.
  6. Surgery: In some instances, surgery may be necessary to remove part of the lung (lobectomy) or the entire lung (pneumonectomy) if the effusion is caused by a localized tumor or to treat complications like empyema.
  7. Management of Underlying Conditions: Treating the underlying condition is crucial. For example, diuretics and other medications may be used to manage heart failure, antibiotics for infections, and immunosuppressive drugs for autoimmune-related effusions.
  8. Pleural Perfusion: This is a newer technique where a catheter is placed into the pleural space to continuously circulate chemotherapy drugs directly to the affected area in cases of malignant effusion.
  9. Oxygen Therapy: If the pleural effusion is causing respiratory distress, supplemental oxygen may be provided to ensure adequate oxygenation.
  10. Palliative Care: For effusions that are part of a terminal illness, palliative care may focus on symptom relief and improving quality of life rather than curing the underlying cause.

The choice of treatment is made by a healthcare professional based on the individual patient’s condition, overall health, and the goals of care. It’s important to note that treatment plans may evolve as the patient’s condition changes or as responses to treatment are assessed.

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