Prominent lumps in the milk ducts block the ducts, and yellow, watery, coffee-colored, or even bright red nipple overflow, i.e., hemorrhage, can be produced when secretion is vigorous. Bleeding water in the breast is the bloody overflow from the nipple. The possible causes of nipple bleeding in non-lactating patients are as follows: 1. Breast cancer: there is a lump in the breast, and nipple bleeding occurs at the same time; 2. Hemorrhagic necrotizing mastitis: the patient manifests nipple bleeding; 3. Other causes: such as trauma leading to nipple bleeding; if the nipple overflow is yellow or watery, it may be intraductal papilloma, which is also known as pre-cancerous lesions, and it is not suitable to be ignored and needs to be examined in a timely manner.