American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What is the significance of a positive HBsAg in relation to hepatitis B infection?

1. Indicates recovery from infection

2. Indicates acute or chronic infection

3. Indicates immunity to infection

4. Indicates need for vaccination

The correct answer is: Indicates acute or chronic infection

A positive HBsAg (Hepatitis B surface antigen) is a crucial marker for determining the status of an individual with respect to hepatitis B infection. It indicates the presence of the hepatitis B virus (HBV) in the bloodstream. This marker signifies that the virus is actively replicating, which means the individual is either experiencing an acute infection or has a chronic infection. Monitoring HBsAg levels is essential in managing hepatitis B, as it helps clinicians assess whether an infection is new (acute) or has persisted over a longer period (chronic). Acute infections tend to show HBsAg positivity for a limited duration, while chronic infections will show persistent positivity over six months or more. In contrast, the other options present different scenarios related to hepatitis B that do not correlate with the meaning of a positive HBsAg. For example, recovery from infection typically results in the presence of antibodies to HBsAg (anti-HBs) rather than HBsAg itself. Hence, a positive HBsAg would not indicate recovery. Similarly, immunity to hepatitis B infection, either from vaccination or previous infection, is reflected in the presence of antibodies (anti-HBs) rather than the antigen (HBsAg). Lastly, the need for vaccination is