Chilaiditi’s syndrome with perforation
Here is a slightly confusing case – you will remember how interposition of the colon between the right lobe of liver and diaphragm (a.k.a. Chilaiditi’s syndrome) can mimic free intraperitoneal gas. This elderly woman has Chilaiditi’s syndrome, with dilated bowel below both hemidiaphragms. However note the free gas between the left hemidiaphragm and the bowel wall (yellow arrow), as well as Rigler’s sign (white arrows). The patient had perforated her large bowel due to ischaemia.