Boils are usually caused by a bacteria called Staphylococcus (staph). Some staph infections develop into abscesses and can become serious very quickly. This germ can be present on normal skin and enters the body through tiny breaks in the skin or by traveling down a hair to the follicle.
Most abscesses are caused by an infection with staphylococcal bacteria. When bacteria enter the body, the immune system sends white blood cells to fight the infection. A cavity is created, which fills with pus to form an abscess. The pus contains a mixture of dead tissue, white blood cells and bacteria.
During the procedure, the surgeon makes a cut (incision) in the abscess, to allow the pus to drain out. They may also take a sample of pus for testing. Once all of the pus has been removed, the surgeon will clean the hole that is left by the abscess using sterile saline (a salt solution).