Failure to detect a gestational sac at 50 days does not necessarily mean that the pregnancy is ectopic, but can also be caused by abnormal embryo development, irregular menstruation and other reasons. The reason for not finding a gestational sac at 50 days depends on the individual’s own health condition. If you have a regular menstrual cycle of about 30 days, the sac and cardiovascular pulsations are usually present at 50 days of pregnancy. If the gestational sac is not detected on the 50th day of pregnancy, a blood test for human chorionic gonadotropin (HCG) is required. If the level of HCG is elevated or lowered, and there is vaginal bleeding and pain in the lower abdomen, the development of the embryo may be abnormal. If the menstrual cycle is irregular, about 40 days, and the gestational sac is not detected on the 50th day of pregnancy, and the level of human chorionic gonadotropin is doubled, there is no pain in the lower abdomen, no vaginal bleeding, etc., the ultrasound can be rechecked after one week to confirm the development of the gestational sac. Ectopic pregnancy, on the other hand, may present with symptoms such as lower abdominal pain, nausea, anal cramping sensation, and a small amount of dark red or dark brown blood from the vagina. In severe cases, symptoms such as fainting and shock may also occur. Ultrasound can be performed in the hospital to check the fallopian tubes or ovaries for masses to confirm whether the pregnancy is ectopic. If the gestational sac cannot be detected for 50 days, it is recommended that a targeted treatment plan be carried out under the guidance of a doctor.