Peritoneal and omental rule 7: Pneumoperitoneum

1-Definition: Presence of air in the peritoneal cavity.
2-Causes:
-Following surgical operation.
Should be resolved within 3-7 days, if not, should be considered surgical emergency.
-Other causes rather than surgery as bowel perforation should be considered surgical emergency.
3-Rigler's sign:
Can be observed in plain abdomen and CT.
Air outlining both inside and outside of the walls of the bowel.
Causes:
Perforated bowel.
Perforated diverticulum.
Pneumatosis intestinalis.