66 Year Old Male With No Known Gallbladder Problems Or

66 year old male with no known gallbladder problems or symptoms accuses excruciating pain in the right quad, presents himself in the Emergency Room and after abdominal CAT scan is told his gallbladder is 3 times larger than normal He is given morphine injections every several hours with not too much success until the next day when doctors decide to remove his gallbladder. After surgery he is told his gallbladder was gangrenous. HOW IS IT POSSIBLE TO HAVE A GANGRENOUS gallbladder and not feel anything? How long does it take for the gallbladder to become gangrenous? What are its causes? He was told there were no stones. therefore what caused the gangrene? Thank you for your answer.