If you want to terminate a pregnancy more than 20 days after the last menstrual period, you cannot have a medical abortion. You need to decide whether you can have a medical abortion based on the specifics of your pregnancy and ultrasound. The last menstrual period counts more than 20 days of pregnancy, the fertilized egg at this time may still be in the fallopian tube to move, has not yet in the uterine cavity to bed growth. If you take drugs for abortion, it is possible that the fertilized egg will be killed in the fallopian tube, causing danger such as bleeding or rupture of the fallopian tube. Or at this time the size of the gestational sac is very small, do ultrasound can not see the presence of the gestational sac, the probability of failure to do medication abortion is very high. If you want to have a medical abortion, you should have an ultrasound examination, the gestational sac is located in the uterine cavity, and the diameter of the gestational sac is about 10mm, you can consider having a medical abortion under the guidance of a doctor. Therefore, if you want to have a medical abortion, you should do it under the guidance of a doctor.