Is a c-section considered medically necessary with an unhealed anal fissure? i had surgery year before for fissure, and it never healed.

Depends: Without seeing your entire medical history, as well as the reason for the fissure and why it didn't heal, it's a little difficult to say whether cesarean indicated or not. If you have an area close to the perineum that has not healed, I don't think this is Cesarean is a bad idea at all. That's a delicate area and healing from a cesarean is not bad .