Rigler's sign
（重定向自Double wall sign）
![Double wall sign. This is a secondary sign of pneumoperitoneum. Patient is supine, and air within the abdomen and lumen of the bowel accentuate both sides of the bowel wall.](/Images/godic/202501/09/Double_wall_sign3633.jpg")
Rigler's sign, also known as the double wall sign, is a radiologic sign seen on an x-ray of the abdomen when air is present on both sides of the intestine; a Rigler's sign is present when air is present on the inside (luminal side) and the outside (peritoneal side). Air in the peritoneum is considered abnormal, unless the patient had a recent abdominal surgery.