What is an abscess typically filled with?

An abscess is a localized collection of pus that occurs in response to infection, inflammation, or the presence of foreign substances in the body. The pus in an abscess consists of dead white blood cells, bacteria, and cellular debris, which accumulates as the immune system fights off the infection. This is a common occurrence in various types of infections, especially bacterial infections, where the body's immune response leads to the formation of an abscess to encapsulate the infection and prevent it from spreading further.

While blood, air, and other kinds of fluids could be present in different medical conditions, they do not describe the classic contents of an abscess. Blood may be involved in various types of wounds or injuries, air could be present in instances like pneumothorax, and other fluids might refer to serous or lymphatic fluid in different contexts but do not represent the specific condition of an abscess. Therefore, pus is the definitive and characteristic substance that indicates the presence of an abscess.