Fetal arrest ultrasound may also have the chance of misdiagnosis, but in general the examination is accurate. Under normal circumstances the calculation of pregnancy is from the first day of the last menstrual period, if the ultrasound examination of the size of the gestational sac and the time of the cessation of menstruation, generally not misdiagnosis, if the size of the gestational sac, significantly smaller than the time of the menstrual cycle, it is necessary to carry out further monitoring. Criteria for embryonic arrest need to be determined by vaginal ultrasound. A gestational sac that is greater than 25 mm in diameter, with no embryonic tissue visible within the sac, and a fetal head-rump length greater than 7 mm, but no heartbeat is usually diagnostic. When cessation of embryonic development is suspected, the menstrual cycle should be counted. Some women have smaller gestational sacs because of late fertilization due to irregular menstruation, and blood levels of chorionic gonadotropin and luteinizing hormone need to be tested to help determine whether cessation of embryonic development exists. It is recommended to consult the Obstetrics and Gynecology Department of a regular hospital if you suspect that the embryo has stopped developing.