Rigler's triad is a combination of findings on an abdominal radiograph of people with gallstone ileus, a condition where a large gallstone causes bowel obstruction.

Rigler's triad consists of: (1) small bowel obstruction, (2) a gallstone outside the gallbladder, and (3) air in the bile ducts.

It is most commonly seen in 6th to 7th decade of life and affects females more often.

Due to the fistula formation between the small intestine and gallbladder, large stones can lodge in the small bowel, leading to its obstruction.

It is due to the transfer of air from bowel through the fistula into the biliary tract.