not an artifact

While looking at x-rays in medicine we often talk about air-fluid levels. Its a pretty simple concept, really.  Its like a glass of water: air on top, water on bottom, and a line in between.

We usually see air-fluid levels in the stomach or in the small bowel when there is an obstruction.

 Last week, I saw the most impressive air fluid level yet- an entire-abdomen air-fluid level:

That line is the air-fluid level created from all the stool, gas, and pus free in the abdomen after several days of leaking from holes in intestine caused by typhoid. I've never seen a whole abdominal air-fluid level like that. (Mostly because it is usually so obvious that these patients need an operation that we don't get x-rays because of the cost).