Q: Does blood (any amount) break your wudu’, whether it stained the clothes or was in a place that won’t stain the clothes like a scratch on the hand? Also, if I did ablution for a certain prayer and while praying, the normal female discharges came out, do I need to redo my wudu to pray the sunnah?
A: Blood does break your wudu if an abundant amount comes out regardless if it stains your clothes or not. If you are absolutely certain that normal female discharge has come out (as a rare occurrence) during prayer, you must repeat purification and prayer. Allah knows best.
Source: Bidayat al-Abid