Normally, the gestational sac can be seen at 5-6 weeks of pregnancy. If the usual menstrual cycle is regular, the pregnancy can be calculated from the first day of the last menstrual period. The normal pregnancy is around 35-42 days and the gestational sac can be seen by ultrasound examination to determine whether the pregnancy is intrauterine or extrauterine. If the menstrual cycle is usually irregular and often delayed, ovulation will be delayed accordingly and the appearance of the pregnancy sac will also be delayed, so the time to check the pregnancy sac will be relatively later. At this time, the blood progesterone and the doubling of blood hCG can be used to initially determine whether the development of the pregnancy sac is normal. If there is no abdominal pain and bleeding during pregnancy, you can go for an ultrasound examination around 7 weeks of pregnancy to see the presence of primitive heart tube pulsation. Around 35-42 days of pregnancy, it is recommended to do a negative ultrasound. If you want to do an abdominal ultrasound, you need to hold urine to be able to see the gestational sac clearly.