Hi & Welcome to HCM.
I appreciate your concern for your beloved father.
A "collapsed gallbladder" refers to a condition in which the gallbladder remains in a prolonged deflated (contracted) state.
Under normal circumstances, the gallbladder expands as it fills with bile from the
liver. When bile (secretion from the liver) is needed for digestion of fats, the gallbladder contracts, squeezing the bile into the
small intestine. At this stage, it appears deflated. If the gallbladder is unable to expand to receive fresh bile, it is then said to be collapsed.
It can also be due to
chronic cholecystitis (inflammation of the
gall bladder) caused by gallstones. Rarely, it can also be due to a ruptured gallbladder, a life-threatening condition which needs to be surgically treated.
You need to consult a surgical gastroenterologist for further evaluation.
Hope this answers your query.
Kindly rate this answer if you are convinced.