Detecting breast tissue damage from pumping can be determined by several indicators. Firstly, you may experience pain or discomfort during pumping sessions, such as soreness, tenderness, or a burning sensation in the breast. Additionally, visible signs of tissue damage can include bruising, redness, swelling, or abrasions on the nipple or areola. If you notice blood in your expressed breast milk or if the milk appears pink or discolored, it could also indicate tissue damage. It's essential to consult a healthcare professional if you suspect breast tissue damage from pumping for proper evaluation and guidance.