Bleeding again 20 days after the abortion, there are two possibilities, as follows: 1, after the abortion, there are still residual embryos and appendages in the uterine cavity, ultrasonography and to check the specific value of blood HCG. Through the above examination to know whether there is any residue in the uterine cavity, if suggests that there is corresponding residue, need to be given again to clear the uterus treatment, and if necessary, to carry out hysteroscopic conditions of the uterus is appropriate. 2.After abortion or drug abortion, the menstrual cycle is re-established and normal menstruation occurs. At this time, it is still necessary to carry out the appropriate ultrasound examination to find out whether there is any residue in the uterine cavity, if there is no obvious residue, then it can be considered that it is the re-occurrence of menstruation caused by bleeding again.