The mnemonic
Free air: Rigler and Football
What each word stands for
- Free airGas under the diaphragm on erect chest film
- RiglerGas on both sides of the bowel wall
- FootballLarge gas collection outlining the abdomen on supine film
Why it matters clinically
Perforation of a hollow viscus is a surgical emergency.
Where it stops being reliable
Small leaks can be missed; CT is more sensitive.
Teaching aid, still awaiting independent review. Confirm facts in a standard source.