What are the possible causes of ascites with pleural effusion?

Possible Causes of Ascites with Pleural Effusion

The combination of ascites and pleural effusion most commonly indicates hepatic hydrothorax from cirrhosis with portal hypertension, but you must systematically exclude malignancy, infection, cardiac disease, and other causes of transudative or exudative effusions.

Primary Hepatic Causes

Hepatic Hydrothorax (Most Common)

• Hepatic hydrothorax is a transudative pleural effusion occurring in 4-12% of cirrhotic patients with portal hypertension, typically presenting as a right-sided effusion (73% right, 17% left, 10% bilateral) 1.
• The pleural fluid originates from the peritoneal cavity and migrates through small diaphragmatic defects driven by negative intrathoracic pressure during inspiration 1.
• Notably, 9% of patients with hepatic hydrothorax have no clinically apparent ascites, making the diagnosis challenging 1.
• A serum-to-pleural fluid albumin gradient >1.1 g/dL strongly suggests hepatic hydrothorax 1.
• These patients have extremely poor prognosis with 74% mortality at 90 days despite relatively low MELD scores, far exceeding predicted mortality 1.

Malignant Causes

Peritoneal Carcinomatosis with Malignant Pleural Effusion

• Malignancy is the most common cause of massive pleural effusions and frequently presents with both ascites and pleural fluid 1.
• Lung cancer (25-52% of malignant pleural effusions), breast cancer (3-27%), and lymphoma (12-22%) are the most common primary tumors causing this combination 1.
• A serum-to-pleural fluid albumin gradient ≤1.1 g/dL, left-sided effusion, or absence of ascites should raise suspicion for malignancy rather than hepatic hydrothorax 1.
• Pleuroperitoneal communication can occur with malignant ascites, allowing rapid fluid migration between compartments 2.
• Elevated CA-125 with ascites and pleural effusion may indicate ovarian or other gynecologic malignancies, though pseudo-Meigs syndrome from benign uterine leiomyomas can mimic this presentation 3, 4.

Infectious Causes

Spontaneous Bacterial Peritonitis with Spontaneous Bacterial Empyema

• Patients with cirrhotic ascites who develop bacterial infection can present with both spontaneous bacterial peritonitis (SBP) and spontaneous bacterial empyema (SBE) 1.
• SBE is diagnosed when pleural fluid absolute neutrophil count exceeds 250/mm³, similar to SBP criteria 1.
• Diagnostic paracentesis should be performed immediately in any hospitalized cirrhotic patient with ascites, even without symptoms, and thoracentesis should follow if pleural effusion is present and paracentesis is negative 1.
• Up to one-third of patients with spontaneous infections may be entirely asymptomatic or present only with encephalopathy and acute kidney injury 1.

Parapneumonic Effusion with Secondary Ascites

• Pneumonia complicated by parapneumonic effusion occurs in 1-40% of hospitalized adults, with the inflammatory process potentially extending transdiaphragmatically 5.
• The most common causative organisms include Streptococcus pneumoniae, Staphylococcus aureus, and β-hemolytic streptococci 5.
• Perihepatic abscess can cause pleural effusion through direct transdiaphragmatic extension, pleuroperitoneal communication, or inflammatory response, with right-sided effusions being more common due to liver anatomy 6.

Cardiac Causes

Congestive Heart Failure

• Bilateral pleural effusions with ascites in the setting of cardiomegaly on chest radiograph strongly suggests cardiac etiology 1.
• Cardiopulmonary disease must be excluded before diagnosing hepatic hydrothorax 1.

Rare and Miscellaneous Causes

Autoimmune Conditions

• Systemic lupus erythematosus (SLE) can present with ascites, pleural effusion, and elevated CA-125 (Tjalma syndrome), mimicking malignancy 3.

Pancreatitis

• Pancreatic ascites with sympathetic pleural effusion should be considered, particularly if the serum-to-pleural fluid albumin gradient is ≤1.1 g/dL 1.

Critical Diagnostic Approach

When evaluating ascites with pleural effusion, immediately perform:

• Diagnostic paracentesis with cell count, differential, total protein, LDH, glucose, pH, and culture (inoculate ≥10 mL into blood culture bottles at bedside) 1.
• Diagnostic thoracentesis if infection is suspected and paracentesis is negative, or if the clinical picture is atypical for hepatic hydrothorax 1.
• Calculate serum-to-pleural fluid albumin gradient to differentiate portal hypertension-related (>1.1 g/dL) from other causes (≤1.1 g/dL) 1.
• Obtain simultaneous blood cultures to increase organism isolation rates 1.
• Consider peritoneal scintigraphy with Tc-99m sulfur colloid if pleuroperitoneal communication needs confirmation, as rapid tracer migration suggests diaphragmatic defect 7, 2, 8.

Common Pitfalls to Avoid

• Do not assume all ascites with pleural effusion in cirrhotic patients is benign hepatic hydrothorax—always exclude infection, malignancy, and cardiopulmonary disease 1.
• Left-sided or bilateral effusions without ascites should prompt aggressive workup for alternative diagnoses 1.
• Never delay diagnostic paracentesis and thoracentesis in suspected infection—mortality increases 10% for every hour antibiotics are delayed in cirrhotic patients with septic shock 1.
• Avoid chest tube insertion for hepatic hydrothorax due to high complication rates including protein depletion, malnutrition, and renal dysfunction 1.