Sometimes scar tissue can cause problems, it depends where it is and how bad it is. The scar tissue could be a result of the d&c or could be endomentriosis. Did your doctor mention if they thought it would cause a problem? I've had endo on 1 of my ovaries and it didn't cause me any problems. It won't go away by itself. If your concerned you should ask your doctor for more information, don't worry too much until you talk to your doctor.
I did have a D&C a few hours after I miscarried. Does that mean it's left over scar tissue from the surgery?
I'm sorry for your loss. Did you have a d&c or some other type of operation? Did your doctor explain how you have scar tissue on your ovary? Could he have meant endometriosis? If it's endo then it may or may not cause problems depending on how much endo is present and if you have any symptoms. You may need to speak with your doctor again to see exactly what's on your ovary and if you need follow up tests.