Ascites with Pleural Effusion: Diagnostic Approach and Causes

Primary Hepatic Causes

Hepatic hydrothorax is a transudative pleural effusion occurring in 4-12% of cirrhotic patients with portal hypertension, typically presenting as a right-sided effusion, according to the American Association for the Study of Liver Diseases 1, 2, 3.
The pleural fluid originates from the peritoneal cavity and migrates through small diaphragmatic defects driven by negative intrathoracic pressure during inspiration, as reported by the American Association for the Study of Liver Diseases 1, 2, 4.
Notably, 9% of patients with hepatic hydrothorax have no clinically apparent ascites, making the diagnosis challenging, as noted by the American Association for the Study of Liver Diseases 1, 2.
A serum-to-pleural fluid albumin gradient >1.1 g/dL strongly suggests hepatic hydrothorax, according to the American Association for the Study of Liver Diseases 1, 2, 4.
These patients have extremely poor prognosis with 74% mortality at 90 days despite relatively low MELD scores, far exceeding predicted mortality, as reported by the American Association for the Study of Liver Diseases 1, 4.

Malignancy is the most common cause of massive pleural effusions and frequently presents with both ascites and pleural fluid, according to the American Thoracic Society 5.
Lung cancer, breast cancer, and lymphoma are the most common primary tumors causing this combination, as reported by the American Thoracic Society 5.
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, as noted by the American Association for the Study of Liver Diseases 1, 2.

Patients with cirrhotic ascites who develop bacterial infection can present with both spontaneous bacterial peritonitis (SBP) and spontaneous bacterial empyema (SBE), according to the American Association for the Study of Liver Diseases 6.
SBE is diagnosed when pleural fluid absolute neutrophil count exceeds 250/mm³, similar to SBP criteria, as reported by the American Association for the Study of Liver Diseases 6.
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, as recommended by the American Association for the Study of Liver Diseases 6.

Bilateral pleural effusions with ascites in the setting of cardiomegaly on chest radiograph strongly suggests cardiac etiology, according to the American Thoracic Society 5.
Cardiopulmonary disease must be excluded before diagnosing hepatic hydrothorax, as noted by the European Association for the Study of the Liver 3, 4.

Diagnostic paracentesis with cell count, differential, total protein, LDH, glucose, pH, and culture should be performed immediately in any hospitalized patient with ascites, as recommended by the American Association for the Study of Liver Diseases 6.
Diagnostic thoracentesis should be performed if infection is suspected and paracentesis is negative, or if the clinical picture is atypical for hepatic hydrothorax, as recommended by the American Association for the Study of Liver Diseases 6.
Calculate serum-to-pleural fluid albumin gradient to differentiate portal hypertension-related (>1.1 g/dL) from other causes (≤1.1 g/dL), as reported by the American Association for the Study of Liver Diseases 1, 2, 4.