A 52-year-old woman with a history of cirrhosis due to chronic hepatitis C experiences worsening dyspnea. She has no other medical conditions. Vital signs are within normal limits. Physical examination shows normal jugular venous pressure, right-sided dullness to percussion and decreased breath sounds, normal heart sounds, and moderate-sized ascites. Chest x-ray reveals a large right-sided pleural effusion with no parenchymal lesions. Thoracentesis yields transudative fluid with normal cell counts. Which of the following is the most likely underlying mechanism of this patient's pulmonary findings?

Question

A 52-year-old woman with a history of cirrhosis due to chronic hepatitis C experiences worsening dyspnea.  She has no other medical conditions.  Vital signs are within normal limits.  Physical examination shows normal jugular venous pressure, right-sided dullness to percussion and decreased breath sounds, normal heart sounds, and moderate-sized ascites.  Chest x-ray reveals a large right-sided pleural effusion with no parenchymal lesions.  Thoracentesis yields transudative fluid with normal cell counts.  Which of the following is the most likely underlying mechanism of this patient's pulmonary findings?

Quizplus · Accepted Answer

This patient with cirrhosis complicated by ascites who presents with a right-sided, transudative pleural effusion most likely has a hepatic hydrothorax. As ascites fluid accumulates in the abdomen, increased intraabdominal pressure can force fluid into the chest cavity through small fenestrations in the diaphragm; fluid movement across the diaphragm occurs most often on the right side. Because the development of ascites in patients with cirrhosis is driven by changes in hydrostatic and oncotic pressure (ie, increased hydrostatic pressure due to portal venous hypertension and decreased oncotic pressure due to hypoalbuminemia), the pleural fluid in hepatic hydrothorax is transudative by Light criteria. (Choice B) Inflammatory disruption of the visceral pleural mesothelium can occur in pneumonia, allowing bacteria in the alveoli to translocate into the pleural space and cause a complicated parapneumonic effusion. Parapneumonic effusions and other pleural effusions resulting from an inflammatory disruption of membrane permeability (eg, rheumatologic effusions, most malignant effusions) are exudative by Light criteria and usually have elevated leukocyte count. (Choice C) Malignant cells that have metastasized to the pleural space can cause pleural effusion by obstructing pleural fluid drainage via parietal pleura lymphatics. Liver cirrhosis predisposes to the development of hepatocellular carcinoma, which could metastasize to the pleural space; however, malignant effusions typically have high lymphocyte count and cytology frequently reveals malignant cells. (Choice D) Mechanical disruption of thoracic lymphatic flow (eg, injury to the thoracic duct) can cause a chylothorax, which is a milky white pleural effusion with very high triglyceride content. Chylothorax is usually exudative by Light criteria. (Choice E) Atelectasis causes a rapid decrease in intrapleural pressure (as alveoli collapse and pull farther away from the chest wall), and the pressure gradient created between the pleural space and the lung may drive the movement of interstitial fluid into the pleural space, causing a transudative pleural effusion. Pleural effusions due to atelectasis are usually relatively small; hepatic hydrothorax is more likely in this patient with a large, right-sided pleural effusion and a history of cirrhosis. Educational objective: Patients with cirrhosis complicated by abdominal ascites may develop a hepatic hydrothorax, which is a transudative, usually right-sided pleural effusion that results from passage of intraabdominal fluid into the chest cavity through small fenestrations in the diaphragm. __________ References: Diagnostic approach to pleural effusion in adults. (http://www.ncbi.nlm.nih.gov/pubmed/16623208)

A 52-Year-Old Woman with a History of Cirrhosis Due to Chronic