40 days postpartum dew did not clean first need to go to the hospital to do ultrasound to see the size of the uterus and the condition of the uterine cavity, because this situation should be ruled out the placenta or fetal membrane residues. If the ultrasound is done and there is placenta or fetal membrane residue, and there are more things need to do a purging surgery, if the residue is less, you can take some medicines to activate blood circulation and eliminate blood stasis to let them be expelled. If the ultrasound shows that there is no residue, but the uterus is relatively large, it can be treated with uterotonin under the guidance of the doctor to strengthen the uterine contraction. If the uterus is normal size, this situation should be suspected to be caused by endometrial inflammation, you can take some anti-inflammatory drugs under the guidance of the doctor.