Cholecystitis

Cholecystitis is an inflammation of the gallbladder, usually caused by a gallstone blocking the bile duct (choledocholithiasis). It can be chronic, characterized by frequent short bouts of abdominal pain, or acute, characterized by lack of appetite, fever, moderate to very severe pain, fatigue, and jaundice.
Acute cholecystitis is a medical emergency and requires hospitalization, although it is usually less serious and urgent than appendicitis. Ultrasound examination of the gall bladder is always indicated and if pain and fever continue to increase, an emergency cholecystectomy is called for. Otherwise, the patient should be given antibiotics for the complications of infection and intravenous saline, refraining from food until the symptoms improve.
A classic sign of cholecystitis is severe pain if the doctor presses on the right side of the abdomen just below the ribcage and asks the patient to breathe deeply.
Chronic cholecystitis requires a cholecystectomy to be scheduled on an elective basis as the disease will not resolve itself.
Acute cholecystitis at NIH
Cholecystitis at Wikipedia
Cholecystitis at Mayo Clinic