Dilatation of the ducts of the breast with a length of 5 mm and a width of 3 mm on the left side and a length of 7 mm and a width of 3 mm on the right side with swelling and pain is referred to as Dilatation of the Ducts of the Mammary Gland (DMD). The cause of ductal dilatation is not clear, but may be related to congenital nipple inversion, breastfeeding disorders, trauma, and bacterial infections. Patients with ductal dilatation may experience a variety of symptoms including nipple discharge, breast pain, and wound breakdown. This may cause the manifestation of dilated and swollen milk ducts. If the patient is not treated in time, ductal dilatation may also cause complications such as mastitis, breast cancer and nipple ulceration, in which a lump can be found when touching the breast, and the impact on the body is more serious. Breast duct dilatation is 5mm long and 3mm wide on the left side, 7mm long and 3mm wide on the right side, and the swelling and pain may be caused by other factors such as tumors, so the patient should go to the hospital in time to take the appropriate treatment for the disease.