The difference between acute and chronic hepatitis B mainly depends on the duration of hepatitis B surface antigen carriage, if the hepatitis B surface antigen is positive and the carriage time is more than six months, it is chronic hepatitis B infection. If the previous test was negative for both pairs of antigens, and this time there is a positive hepatitis B surface antigen, it is considered an acute hepatitis B infection. However, some patients have never had a two-to-one test before, and if they find positive hepatitis B surface antigen this time, they cannot make a diagnosis of acute or chronic hepatitis B. They can be judged by whether they have signs of chronic liver disease, such as whether they have liver palms, spider nevus or hepatic facial features, whether the liver ultrasound indicates changes of chronic liver disease, or whether the liver fibrosis scan indicates a high fibrosis index, all of which are considered chronic hepatitis B infection. If the above tests are still inconclusive a liver biopsy can be done to further clarify.