How do the Poskim define the exact definition of Dam Maka

Shalom U'Beracha!
Nida (66a): Maka from Makor is Tahor according to "Rabotenu Heyedu". How do the Poskim define the exact definition of the Maka? IUD, endmetrial Bx, dysfunctional uterine bleeding, ectopic pregnancy causing uterine bleeding, Fibroids (Tziz eliezer, Dvor Shmuel, Chazan Ish), subchorionic hematoma, bleeding from placenta previa, placental abruption. What is a Maka? Which Gadol precisely define it for us? can you refer me to detailed Gedolei Poskim? I have reviewed Nishmat avraham several times and still do not have a clear understading of this Gemara. Thank you