The yellow fluid flowing from the breast may be caused by physiological reasons, pathological reasons and other factors, and it is recommended that the patient go to the hospital in time for the ultrasound examination of the breast, to identify the cause of the disease and treatment. 1. Physiological reasons: the glandular tissue of the mammary gland has a certain secretion function under the influence of female hormones in the body. Mainly after squeezing the breast and nipple, you can see the opening of the milk ducts in the nipple department has a trace of liquid overflow. Mostly seen in bilateral porous, its color is usually colorless, milky white, yellow, turbid liquid, no smell, generally belong to the normal phenomenon, no special treatment. 2. Pathological causes: generally unilateral single pore, and the amount of overflow is more, the color is dark red or bloody, sometimes yellow liquid. The color is dark red or bloody, sometimes yellow liquid. It is common in inflammation of breast ducts, or breast cancer. It is recommended that patients go to the hospital in time for further diagnosis, and after diagnosis, surgical excision should be carried out according to the condition. It is also recommended to pay attention to the local hygiene of the nipple, relax, drink more water, and ensure sufficient sleep.