If cholecystitis is suspected, routine blood tests, duodenal drainage, ultrasound, radionuclide examination, abdominal x-ray plain film, cholecystokinin test, and fiberoptic laparoscopy can be done. ultrasound is important for the diagnosis of this disease. Cholecystitis is a common disease with a relatively high incidence. It is an inflammation of the gallbladder caused by obstruction of the gallbladder duct and bacterial attack, which mainly occurs after overeating, with abdominal pain, fever and abdominal distension as the main symptoms. The diagnosis can be confirmed by abdominal palpation, laboratory tests and abdominal ultrasound. Abdominal palpation can cause painful symptoms because of touching the enlarged gallbladder. Laboratory tests for blood work, white blood cell count will be mildly elevated and neutrophils will be elevated. If the white blood cell count exceeds 20,000 and there is a leftward nuclear shift and toxic granules, it proves the presence of cholecystitis. The diagnosis is basically confirmed by an enlarged gallbladder visible on abdominal ultrasound. If it is not visible, CT or MRI can be done again for examination. In case of chronic inflammation of the gallbladder by duodenal rectal drainage, such as increased mucus in the bile, piles of white blood cells, positive bacterial culture or parasite examination, it helps a lot in diagnosis. Diagnosis of cholecystitis ultrasound is the most direct test and the most economical, affordable and non-invasive test.