Uterine effusion occurs during pregnancy, often due to the phenomenon of detachment between the uterine wall and the gestational sac, resulting in the rupture of the internal capillaries and bleeding, which cannot be discharged outside the uterine cavity in time and accumulates within the uterine cavity, which is detected by ultrasound examination. The clinical principles of treatment are: first, to give hemostatic treatment to reduce the possibility of further bleeding increase by hemostatic treatment. The second one, progesterone is given intramuscularly or orally, mainly to inhibit the contraction of the smooth muscle of the uterus and to avoid further detachment between the uterine wall and the gestational sac. In this case, in addition to treatment with medication, bed rest and ultrasound monitoring and blood tests for HCG and progesterone are required.