Acute cholecystitis is an immediate inflammation of your gallbladder due mainly to gallstones that block the cystic duct. The block can result in the gallbladder becoming swollen, infected, causing extreme abdominal pain (upper right side of the abdomen). Other signs of acute cholecystitis may include fever, nausea, vomiting, bloating, and tenderness after eating. If left untreated, acute cholecystitis can lead to complications such as infections of the gallbladder, rupture of the gallbladder, or the formation of abscesses. Typically, the physician will perform a physical examination, order blood tests, and perform an abdominal ultrasound, CT scan, HIDA scan, or MRI to confirm gallbladder inflammation and identify any complications.