Cholecystitis: Inflammation of the gallbladder, a complication of gallstones which are formed by cholesterol and pigment (bilirubin) in bile. (Bile is produced in the liver and stored in the gallbladder). Cholecystitis is frequently associated with infection in the gallbladder. Risk factors for cholesterol gallstones include age, obesity, female gender, multiple pregnancies, birth control pills, and heredity. The most common symptom is pain in the upper abdomen. Diagnosis is usually made with ultrasound of the abdomen. Some patients have no symptoms. Patients with mild and infrequent symptoms may consider oral medication to dissolve gallstones. Surgery (standard or laparoscopic) is considered for patients with severe symptoms and for patient with cholecystitis.