A 6-year-old boy is brought to the physician for a 1-day history of diffuse abdominal pain. Last week, he stayed home from school for a day because he wasn’t feeling well. Temperature is 103 F. Physical examination an abdominal fluid wave. He has mild edema at the ankles and periorbitally. IV fluids are administered. Which of the following is the most appropriate next step in diagnosis for this patient’s acute condition?
Biopsy
CT scan with contrast
CT scan without contrast
Paracentesis
Ultrasound
