You're talking about when the placenta comes out right? (some people consider third stage to be when the baby comes out, that's why I ask).
It's best to just let it happen on it's own. It normally comes out between 10 and 30 minutes later. With ds1 it was 12 minutes and with ds2 it was 17 minutes. You shouldn't pull on the cord, which some people do, because it can cause more bleeding and cause part of the placenta to stay attatched to the uterus which can cause more bleeding and infection. If you're not hemoraghing then you don't need Pitocin. Most placentas will come out just fine. Sometimes they'll need to be manually removed, but that's not very common.