If you are asking what happens to the woman that miscarries (needing a DNC) but was unaware she was pregnant; the answer is simple. The fact that she didn't realize she was pregnant is really moot, because whether she knew or not, a miscarriage happens for a reason. In general, regardless of her knowledge of the pregnancy, she would have miscarried anyway. As far as what happens? If the woman has miscarried, a DNC (more properly 'D&C', from the technical terms "dilation and curettage") is performed to insure the inner lining of the uterus is free of any residual tissue. If left untreated, or without the DNC, infection can set in, in addition to the terrible cramps this woman will experience from the body's natural process of trying to slough off the tissue, which is the cause of cramping. Also, in the event the tissue tears abnormally, into the uterine wall, hemorrhage could erupt. Which left untreated could be fatal. I'm not a doctor, but I've been there, many years ago. Many of the herbs used to cause a miscarriage can also be used to complete a miscarriage and avoid unnecessary surgery that may traumatize the uterus. A D&C can increase the risk of future miscarriages, so many women having fertility difficulties may prefer to use herbs as the most appropriate initial treatment after miscarriage.