In an incomplete abortion, you need not take mifepristone. Depending upon the size of products of the pregnancy within the uterus, the management may vary. A few centimeters of products may successfully be expelled by taking misoprostol in the prescribed dose. However, if the retained products are sized at or more than 4 cms, then you may need a short procedures known as suction evacuation / check curettage. The possible adverse effects of an incomplete abortion, if not treated are: infection inside the uterus, heavy bleeding, abdominal cramps, excessive vaginal discharge, etc.