The main reasons for not seeing a gestational sac at 7 weeks of pregnancy include not having been pregnant, too short of pregnancy, undetected ectopic pregnancy, and complete miscarriage. 1. Never been pregnant: some women, due to the urgency of pregnancy, may be mistaken for pregnancy when experiencing delayed menstruation, but in fact, it may be endocrine disorders that cause delayed menstruation, so you should first do a blood β-hCG to determine whether or not you are pregnant. 2. Too short a period of pregnancy: the earliest means of determining pregnancy is blood β-hCG, but the earliest time for ultrasound to determine pregnancy is 5 weeks of gestation, and some women who have irregular menstruation will take longer. Therefore, if you can’t see the gestational sac at 7 weeks of pregnancy, it may be that the sac is still too small to be observed, so you can follow up with ultrasound to observe it. 3. Undetected ectopic pregnancy: most ectopic pregnancies occur in the fallopian tube, but a very small number of ectopic pregnancies can occur in the cervical pregnancy or even abdominal pregnancy, therefore, no gestational sac can be seen in the adnexal area during ultrasound examination. 4. complete miscarriage: if pregnancy after complete miscarriage, then ultrasound in the intrauterine and extrauterine are not found in the gestational sac and other gestational material. If you can’t see the gestational sac at 7 weeks of pregnancy, you should go to the hospital in time and do relevant auxiliary examinations to clarify the cause of the disease and guide the treatment.