From the Guidelines
Right pleural effusion is most commonly caused by congestive heart failure, malignancy, pneumonia, and liver cirrhosis, with the specific etiology often determined by whether the effusion is transudative or exudative, as indicated by the most recent study 1. The causes of right pleural effusion can be diverse, ranging from systemic conditions to localized diseases affecting the pleura.
- Common causes include:
- Congestive heart failure, which increases hydrostatic pressure in the pulmonary circulation, forcing fluid into the pleural space
- Pneumonia, triggering an inflammatory response that increases pleural membrane permeability, allowing fluid to accumulate
- Malignancies, particularly lung cancer, breast cancer, and lymphoma, which can directly invade the pleura or block lymphatic drainage
- Liver cirrhosis with ascites, leading to fluid crossing the diaphragm into the right pleural space (hepatic hydrothorax)
- Other causes include pancreatitis, tuberculosis, autoimmune diseases like rheumatoid arthritis and lupus, trauma, and iatrogenic causes such as medication reactions or post-surgical complications, as noted in 1.
- The classification of pleural effusion as transudate or exudate reflects the pathophysiological mechanisms explaining fluid formation, with more than 80% of transudates due to heart failure, followed by liver cirrhosis, hypoalbuminemia, nephrotic syndrome, and atelectasis, as stated in 1.
- Diagnosis typically requires thoracentesis with fluid analysis to determine the underlying cause and guide appropriate treatment, with imaging modalities such as chest radiographs, thoracic ultrasound, and chest CT aiding in the detection and characterization of pleural effusions, as discussed in 1.
From the Research
Causes of Right Pleural Effusion
The causes of right pleural effusion can be varied and are often associated with underlying diseases. Some of the common causes include:
- Congestive heart failure 2, 3
- Cancer, with lung cancer being the most common cause of malignant pleural effusion, followed by breast cancer 2
- Pneumonia 2
- Pulmonary embolism 2, 3
- Right heart failure (RHF) 4
- Idiopathic and familial pulmonary arterial hypertension (IPAH and FPAH) 4
- Infections 3
- Collagen vascular diseases 3
- Drugs 3
- Cardiac surgery 3
- Hepatic hydrothorax 3
Characteristics of Pleural Effusions
Pleural effusions can be classified as transudates or exudates, with transudates often being caused by congestive heart failure and hepatic hydrothorax, and exudates being caused by infections, pulmonary embolism, and other conditions 2, 3. The majority of effusions due to RHF are trace to small and right-sided or bilateral 4.
Diagnosis and Treatment
Diagnosis of pleural effusion often involves pleural fluid puncture (pleural tap) to differentiate between transudate and exudate 2. Treatment of pleural effusion depends on the underlying cause and can range from pleurodesis to thoracoscopy and video-assisted thoracoscopy, to the placement of a permanently indwelling pleural catheter 2. In cases of malignant pleural effusions, treatment is often palliative and can include sequential thoracenteses or tube thoracostomy with or without sclerotherapy 5.