Cholecystitis

Acute cholecystitis is inflammation of the gallbladder, usually caused by a gallstone lodged in the cystic duct. Bile cannot leave the gallbladder, so it accumulates, distends the organ, and raises pressure within its wall. Venous and lymphatic drainage become impaired, inflammation intensifies, and bacterial overgrowth may follow. Progressive inflammation can cause tissue necrosis, perforation, an abscess, or sepsis. This mechanism explains why the pain of cholecystitis is usually steady and persistent rather than a short episode that resolves when the stone moves. Pain is typically in the right upper quadrant (RUQ), may follow a meal, and can radiate to the right shoulder or scapula. Nausea, vomiting, fever, and reduced oral intake are common accompaniments. A gallstone is not automatically cholecystitis. A stone that briefly obstructs the cystic duct can cause biliary colic without sustained inflammation. The clinical question is whether the patient has moved from transient obstruction to an inflamed, potentially infected gallbladder.