Pathanatomy

Cholecystitis
Cholecystitis is inflammation of the gallbladder. The gallbladder is a small, pear-shaped organ on the right side of the belly (abdomen), beneath the liver. The gallbladder holds a digestive fluid (bile) that's released into the small intestine

In most cases, gallstones blocking the tube leading out of the gallbladder cause cholecystitis. This results in a bile buildup that can cause inflammation. Other causes of cholecystitis include bile duct problems, tumors, serious illness and certain infections.

Symptoms of cholecystitis may include:
Severe pain in your upper right or center abdomen
Pain that spreads to your right shoulder or back
Tenderness over your abdomen when it's touched
Nausea
Vomiting
Fever

Causes
Cholecystitis is when your gallbladder is inflamed. Gallbladder inflammation can be caused by :-
Gallstones. Most often, cholecystitis is the result of hard particles that develop in your gallbladder (gallstones). Gallstones can block the tube (cystic duct) through which bile flows when it leaves the gallbladder.

Tumor. A tumor may prevent bile from draining out of your gallbladder properly. This causes bile buildup that can lead to cholecystitis.
Bile duct blockage. Stones or thickened bile and tiny particles (sludge) can block the bile duct and lead to cholecystitis. Kinking or scarring of the bile ducts can also cause blockage.

Complications
Infection within the gallbladder. If bile builds up within your gallbladder, causing cholecystitis, the bile may become infected
Death of gallbladder tissue. Untreated cholecystitis can cause tissue in the gallbladder to die (gangrene). It's the most common complication, especially among older people, those who wait to get treatment and those with diabetes.

Prevention
Lose weight slowly. Rapid weight loss can increase the risk of gallstones.
Maintain a healthy weight. Being overweight makes you more likely to develop gallstones. To achieve a healthy weight, reduce calories and increase your physical activity.