Air on the AXR

An elderly lady with a complex abdominal surgical history presented with what seemed to be a 2 day history of obstruction - vomiting, distension, and severe abdominal pain. Allowed in these circumstances, see below the AXR. 

What 3 important findings can you see?

1. There are distended loops of small intestine in the left lower quadrant, compatible with obstruction.
   
2. There is an IVC filter in situ (PEs post her surgery)
   
3. There is air in the hepatic portal system in the liver.
   

The air in the hepatic portal system is a VERY bad sign.  Traditionally, hepatic portal air seen on the AXR carries a 75% mortality.  In this case there is air in the wall of the stomach (as seen above) and all the way down the intestine.  This is most likely from ischaemia (she had a high lactate and WCC) although there are other causes and management depends on the underlying cause.  There can be non-fatal causes, but they are rare.