Blighten ovum

I was diagnosed with an anembryonic pregnancy, also known as a blighten ovum, which will result in a miscarriage the baby does not develop. But I've never had a symptom of miscarriage before, not even spotting.  I sought a second opinion and received the  same result. My OB offered me the option of waiting for a miscarriage or undergoing a raspa.  Which of the two options is the best?