Not seeing the gestational sac on the 15th day after IVF transfer is not necessarily ectopic pregnancy. In vitro fertilization-embryo transfer (IVF-ET) technique, ectopic pregnancy is ectopic pregnancy. Generally, pregnancy can be confirmed by testing blood or urine HCG (human chorionic gonadotropin) level around 12-14 days after embryo transfer, and ultrasound can be done around 20-25 days after the transfer (35-40 days after the pregnancy) to make sure whether it is an intrauterine pregnancy. Therefore, when the gestational sac is not visible on the 15th day after transplantation, it is not necessarily an ectopic pregnancy and can be rechecked as prescribed by the doctor. When no gestational sac is seen in the uterine cavity during ultrasound examination on the 20th to 25th day after the transplantation, but abnormal echogenic areas are detected in the parietal uterus and fetal buds and buds are seen, ectopic pregnancy can be diagnosed, and medications or surgical treatments need to be given according to the condition of the patient as per the doctor’s instruction to avoid rupture which may lead to hemorrhagic shock and other serious complications. In the clinic, when you can’t see the gestational sac on the 15th day after in vitro fertilization, you need to follow the doctor’s advice to observe and recheck again.