Cholecystitis (say "koh-lih-sis-TY-tus") is inflammation of the gallbladder. The gallbladder stores bile. Bile helps the body digest food. Normally, the bile flows from the gallbladder to the small intestine.
A gallstone stuck in the cystic duct is most often the cause of sudden (acute) cholecystitis. The cystic duct is the tube that carries the bile out of the gallbladder. The gallstone blocks the bile from leaving the gallbladder. This results in an irritated and swollen gallbladder.
The swollen gallbladder can also be caused by infection or injury to the belly.
Cholecystitis has to be treated right away and likely in the hospital. Surgery is the usual treatment.