To determine whether the breast is open or not, it is easier to judge during breastfeeding, but during non-breastfeeding period, you need to use the machine to test. Secondly, if there is very little milk spillage when pressing the breast, accompanied by breast swelling and pain, hard lumps, redness and swelling, or no milk secretion, it is considered to be caused by blockage of the milk ducts, which may lead to breast inflammation and abscess over time. If you are not breastfeeding, you can go to the hospital for an imaging examination to confirm the diagnosis.