Ultrasound shows liquid dark area, may be the pregnancy sac, may be the uterine cavity inflammation or uterine bleeding and so on, need to be specifically analyzed. 1. pregnancy: after pregnancy due to the relatively short days of pregnancy, the gestational sac is small, can not be clearly observed, can only see the liquid dark area, if at this time the human chorionic gonadotropin level is elevated, may be pregnant. 2. Inflammation of the uterine cavity: If there is inflammation in the uterus, it may lead to inflammatory fluid oozing out, which is manifested as a liquid dark area in the uterine cavity, which is not a gestational sac. 3. Uterine hemorrhage: after surgery in the uterine cavity will lead to bleeding in the uterus, and at this time for ultrasound, it will also be manifested as a liquid dark area, rather than a gestational sac. If there is a liquid dark area in the uterus, it is recommended to go to the hospital in time to improve the relevant examinations to determine whether it is pregnant.