What happens if someone's gallbladder fails completely?

No such entity: Obstruction, inflammation, gangrene are common pathologies of gb complete failure is not an entity

GB dysfunction: Gallbladder dysfunction can cause symptoms that are most commonly manifest with eating and eating certain types of foods. There are several problems that can occur with the gallbladder to produce a spectrum of symptoms. Gallbladder failure per se is no a disease entity, but i believe most likely represents a gb with a really low ejection fraction.