The abdominal x-ray reveals presence of free intraperitoneal air. The hepatic shadow is obscured by lucency. There is also ‘double wall sign’ or ‘Rigler sign’ visible.
Rigler sign was first described by American Radiologist Dr. Leo Rigler. It is seen in cases of pneumoperitoneum where in the small bowel wall has air on both sides – intraluminal (normal) & extraluminal (abnormal).
Mostly seen on supine abdominal radiographs, Rigler Sign needs large volume of free peritoneal air to manifest.