JoyRenee pretty much said the same things I've said. I had a natural miscarriage and one where I required a d & c to remove the remnants of the pregnancy becuase my body did not dispell anything on its own.
I had 3 successful pregnancies after my first miscarriage (the one with the d & c) and had one successful pregnancy after my natural miscarriage
I miscarried at 5 weeks this weekend and didn't go to the hospital or anything. I knew what was happening and it was so early that if I didn't test I would have just thought it was an extremely bad period. I went to the doctors yesterday and I didn't get anything done but he did take a urine sample to test(which was negative) and make sure the HCG is gone and took some blood. He said that if my bleeding has stopped that everything should be fine and wait for the next cycle to come around.
There aren't any treatments, per se. They just do a pelvic exam to make sure the uterus has gone back down. Some doctors also do blood tests to verify your HCG levels return to 0. I've had two natural miscarriages and all I did was get a pelvic exam afterward. I got pregnant after both miscarriages.
If you've had periods since your miscarriage I wouldn't worry about it.