CASE 16
History: A 71-year-old woman presents with melena, nausea, vomiting, and abdominal pain.
1. What is the minimal amount of free intraperitoneal gas visible on an upright chest film?
A. 1 to 2 mL
B. Approximately 5 mL
C. 10 to 20 mL
D. Approximately 50 mL
E. 100 to 150 mL
2. What is Rigler’s sign?
A. A differential diagnosis for free intraperitoneal gas due to a loop of bowel interposed between the liver and the right diaphragm.
B. A sign of free intraperitoneal gas on a supine abdominal radiograph where both sides of the bowel wall are visible owing to gas on both sides.
C. A sign of free intraperitoneal gas on a supine abdominal radiograph where the inferior surface of the central tendon of the diaphragm is visible.
D. A sign of free intraperitoneal gas on a supine abdominal radiograph where there is an oval central lucency.
3. What imaging procedure is best for demonstrating free intraperitoneal gas?
A. Abdominal radiograph, erect
B. Abdominal radiograph, left decubitus
