What happens to the blood that did not reroute to healthy veins, after successful VNUS closure, during microphlebectomy & when you don't know origin?

I had VNUS closure proc. in legs. Trunk valves are closed, but blood did not reroute to healthy deep veins. Now I need to have micro-phlebectomy. The origin of blood is unknown. How is bleeding controlled during microphlebectomy if origin is unknown?