The probability of a spontaneous abortion being clean is around 70% to 80%, and the vast majority of spontaneous abortions are clean. In general, when spontaneous abortion occurs, the pregnancy sac will be expelled in the early stage through abdominal pain or bleeding, and the vast majority of them can be expelled cleanly. In a few cases, a small amount of tissue remains in the uterine cavity, which is usually manifested by bleeding after 1 week of spontaneous abortion. Therefore, once this symptom occurs, it is recommended to consult a doctor in time, complete the relevant examinations, and under the doctor’s guidance, carry out purging treatment to remove the residual tissue. Generally, it is recommended to repeat the ultrasound examination two weeks after the spontaneous abortion to see if there is any residual tissue in the uterine cavity and to determine whether the abortion is clean.