Review Question - QID 217084

A 44-year-old man presents to the emergency room with a 1-week history of shortness of breath and confusion. He told his daughter he has been having abdominal pain as well. He has a past medical history of alcohol use disorder and cirrhosis. His medications include nadolol and lactulose. His temperature is 102.2°F (39°C), blood pressure is 100/60, pulse is 99/minute, respirations are 15/minute, and oxygen saturation is 100% on room air. Physical examination reveals tenderness throughout the abdomen and shifting dullness with rebound. Chest radiography reveals no acute intrapulmonary process. Which of the following is the most appropriate next step in management?