UKMLA PLAB AMC USMLE Prometric MCQ

a) is seen in about half of perforated appendices
b) Rigler's sign usually requires about 10 mls of free air
c) when due to gastric perforation is more likely to involve the POSTERIOR wall of the stomach
d) when seen in necrotizing enterocolitis immediate surgery is usually indicated
e) on a plain supine film free air is more likely to be seen in the left upper quadrant than the right upper quadrant