In most cases the gestational sac is not visible on ultrasound at 35 days of pregnancy, especially on abdominal ultrasound. In individual cases, where patients ovulate early and conceive early, the pregnancy sac can be seen on ultrasound, but it is very small and may be a false pregnancy sac. And it is better to do vaginal ultrasound at this time, the accuracy of vaginal ultrasound detection is relatively high. When doing abdominal ultrasound, patients need to hold their urine. If the bladder is bigger and presses the patient’s uterus, plus the squeezing of the patient’s uterine muscle layer, the relatively small gestational sacs may be squeezed and not easily monitored. With a negative ultrasound, there is no bladder compression, and if a gestational sac is present, the likelihood of detection is very high. If the patient’s pregnancy sac is detected on day 35 of pregnancy, and the sac is less than 1.0cm, the presence of a false pregnancy sac cannot be ruled out, and monitoring is still needed. And at this time, even if the monitoring of the gestational sac, can not do medication abortion and abortion, because the gestational sac is too small, there is the possibility of false gestational sac; abortion is not easy to observe whether the gestational sac is discharged, it is not easy to judge whether the abortion is successful.