Abstract: Objective　To evaluate the significance of transvaginal ultrasonography in the diagnosis and treatment of bleeding after abortion with mifepristone.Methods　The bleeding causes in 188 cases after medical abortion were analyzed according to the characteristics of transvaginal utero(ovarian ultrasonogram, the pathological changes of endometrium, and the levels of estradiol(E2) and progesterone(P) in the plasm of patients. The different treatments were given based on transvaginal utero-ovarian ultrasonogram.Results　Of 158 cases with uterogenic bleeding after medical abortion, the ovarian ultrasonograms of 67 cases (43.6 %) showed corpus luteum cyst. On the contrary, no corpus luteum cyst was found in the control group (30 cases). The level of estradiol(E2) of patients in group B (cases with ovarian corpus luteum cyst)was much higher than that in group A （ cases without corpus luteum cyst）(P<0.001). During the clinical treatment,the duration of bleeding of the patients in group B was longer than that in group A. In addition, the bleeding of patients in group B stopped after disappearance of corpus luteum cyst.Conclusion　The ovarian corpus luteum persisting and secreting the estrogen and progestogen is one of the causes of bleeding after abortion with mifepristone. The transvaginal ultasonography not only can be used for choosing the patients of medical abortion and for evaluating the effect of abortion, but also can suggest the bleeding causes after abortion with mifepristone and guide the treatment.