What is confounding bias?
Part of the exposure-disease relationship can be explained by another variable.
Matching helps to control which type of bias?
Use groups that have similar distribution in accordance with the variables
(gender, race, age, smoking status)
Describe the pathogenesis and clinical presentation of a gallstone ileus.
Gallstone obstructs cystic duct
This causes a fistula to be created between the gallbladder and small intestine.
Gallstone passes through the fistula and becomes lodged in ileocecal valve.
Intestinal gas backs up into the gallbladder and biliary tree.