Yellow overflow from a single hole on one side of the breast may be related to breast milk residue, papilloma in the milk duct, inflammation and infection, breast cancer and other conditions. 1. Milk residue: If the patient belongs to women after breastfeeding, there may be milk residue in the breast, and after a long time, the trait and color of milk will change, and when the breast is squeezed, there may be yellow liquid coming out. 2. Intraductal papilloma: It belongs to a kind of benign breast duct tumor, there may be lumps in the ducts, and there will be red or yellowish nipple discharge and other phenomena. 3. Inflammatory infections: If the patient has mastitis or breast abscess, it will lead to obvious pain in the breast, lumps, nipple discharge and other manifestations, and there may also be fever. 4. Breast cancer: Breast cancer in the early stage will have breast lumps, nipple discharge or nipple blood. There are other reasons for unilateral single-hole extrusion of yellow fluid from the breast, and it is recommended to consult the doctor in time for examination, clear diagnosis and active treatment.