Cholescintigraphy is the gold standard for diagnosing acute cholecystitis. It involves injecting a radioactive tracer into a vein which then carries it to liver. From liver it flows in bile to gallbladder and eventually into the duodenum. The radiographic image indicates any obstruction in this hepato-biliary tract if present (say due to a stone which is the most common cause of an acute cholecystitis) Alternatively, without going into a clinical investigation, we can also look for a positive Murphy's sign on examination. The right subcostal area of the patient is palpated upon inspiration. Tenderness and pain indicates a positive sign.