What is the Rigler triad?
The combination of gas in the biliary tree; small bowel dilation; and a calcified, ectopic gallstone is a triad of findings described by Rigler. It also has been termed gallstone ileus . This triad is seen in less than half of patients in whom a gallstone erodes into the bowel and causes an obstruction in the distal ileum or the sigmoid colon, the narrowest areas of the small and large bowel, respectively. The triad is uncommon in patients in whom a gallstone erodes into bowel because only a few gallstones are calcified; bowel obstruction is not always present; and the fistula may close, resulting in a lack of biliary gas.
