Extrusion of pus from the breast is a case of bacterial infection in the mammary gland, because the mammary gland has the function of secretion, the secretion is discharged through the mammary ducts and nipples, which is very easy to cause bacterial invasion, and when the resistance is reduced or the bacterial reproduction, it will cause localized infection to form abscess, and there will be the case of extrusion of pus. Tuberculosis infection in the mammary gland can also cause cold abscess, mostly due to tuberculosis bacilli spread through the bloodstream after the formation of localized infection, local extrusion of pus outflow. Plasma cell mastitis can also be a localized infection, mostly seen in the case of inverted nipples and obstruction of the discharge of mammary secretions. The pus should be squeezed out of the nipple, and then go to a regular hospital and be treated promptly. If you have a pus discharge, you need to go to the regular hospital in time, you can take the pus discharge to do bacterial culture, as well as drug sensitivity test, according to the specific situation of the symptomatic treatment.