My patient with cirrhosis has a large right sided pleural effusion with only a small amount of ascites. Could this effusion still be related to his cirrhosis?

Yes! Although we often associate pleural effusions in patients with cirrhosis with the presence of large ascites, some patients present with hepatic hydrothorax even in the absence of significant ascites.1-3  

In fact, in a study involving 77 patients with hepatic hydrothorax, 49% had minimal or small and 9% had no detectable ascites!1  Interestingly, nearly three-quarters of patients in this study had right sided pleural effusion with 10% having bilateral and 17% having left sided effusion only. Hepatic hydrothorax without ascites as the first sign of liver cirrhosis has also been reported.2

Although the mechanism(s) behind hepatic hydrothorax is not fully clear, the passage of peritoneal fluid into the pleural cavity through defects in the tendinous portion of the diaphragm assisted by negative intrathoracic pressure during inspiration is commonly favored. 1-3  

Supportive evidence includes a number of studies involving intraperitoneal injection of air, dyes or technetium 99 m-sulfur colloid that have demonstrated the trans-diaphragmatic flow of ascites into the pleural cavity. 1-4  In the absence of ascites, a complete equilibrium between the amount of ascites produced and its flow into and reabsorption by the pleural cavity is assumed.1,2

Bonus Pearl: Did you know that although most patients with hepatic hydrothorax have a transudative pleural effusion according to Light’s criteria, 1 study showed that 18% of patients may meet the Light’s criteria for an exudative effusion? 5,6

References

  1. Badillo R, Rockey DC. Hepatic hydrothorax: Clinical features, management, and outcomes in 77 patients and review of the literature. Medicine 2014;93:135-142. https://www.ncbi.nlm.nih.gov/pubmed/24797168
  2. Kim JS, Kim CW, Nam HS, et al. Hepatic hydrothorax without ascites as the first sign of liver cirrhosis. Respirology Case Reports 2016;4:16-18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4722098/
  3. Rubinstein D, McInnes IE, Dudley FJ. Hepatic hydrothorax in the absence of clinical ascites: diagnosis and management. Gastroenterology 1985;88:188-91. https://www.ncbi.nlm.nih.gov/pubmed/3964765
  4. Holt KA, Oliviera E, Rohatgi PK. Hepatic hydrothorax demonstration by Tc-99 sulfur colloid ascites scan. Clin Nucl Med 1999;24:609. https://www.ncbi.nlm.nih.gov/pubmed/10439187 
  5. Light RW. New treatment for hepatic hydrothorax? Ann Am Thorac Soc 2016;13:773-74. https://www.atsjournals.org/doi/full/10.1513/AnnalsATS.201603-223ED
  6. Bielsa S, Porcel JM, Castellote J, et al. Solving the Light’s criteria misclassification rate of cardiac and hepatic transudates. Respirology 2012;17”721-726. https://www.ncbi.nlm.nih.gov/pubmed/22372660
My patient with cirrhosis has a large right sided pleural effusion with only a small amount of ascites. Could this effusion still be related to his cirrhosis?

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