Air on either side of the bowel wall on a radiograph is called:
The Rigler sign, also known as the double-wall sign, is a sign of pneumoperitoneum seen on an abdominal radiograph when gas is outlining both sides of the bowel wall, i.e. gas within the bowel's lumen and gas within the peritoneal cavity. It is seen with large amounts of pneumoperitoneum (>1000 mL).
Air under diaphragm sign
Cupola sign
Doges cap sign
Rigler sign
Gastrointestinal Radiology