If a pregnant woman is determined to be pregnant after blood test, but no pregnancy sac can be detected by ultrasound, the reason may be premature examination, ectopic pregnancy, embryonic abortion and miscarriage, etc. If the subject is not pregnant, it is normal that no pregnancy sac can be detected by ultrasound. The details are as follows: 1. Premature examination: Generally, a pregnant woman can find a pregnancy sac in the uterine cavity only after 35 days of menopause through ultrasound examination. If the menopause is less than 35 days, which may be caused by delayed ovulation or poor embryonic development factors, the ultrasound cannot distinguish the gestational sac and will conclude that the gestational sac is not visible. It is recommended that pregnant women should undergo ultrasound examination after 35 days of menopause until a normal gestational sac is detected; 2. Ectopic pregnancy: Ectopic pregnancy means that the fertilized egg is not laid in the uterus but outside the uterine cavity, and the pregnant woman is determined to be pregnant by blood test, but the gestational sac cannot be detected by ultrasound. In this case, the changes in blood HCG and serum progesterone should be closely monitored, while paying close attention to whether the pregnant woman has abdominal pain, vaginal bleeding and other symptoms, and if ectopic pregnancy is confirmed, it should be treated as soon as possible. Clinically, two main treatments are used, namely surgery and medication. For those with less bleeding and mild symptoms, medication can be used, such as methotrexate, and if the condition is unstable and the bleeding is heavy, surgery is feasible, including conservative surgery and radical surgery; 3. Embryonic abortion: the main causes of embryonic abortion may be congenital genetic diseases of parents, sperm quality, endometrial abnormalities and pregnant women If the pregnant woman is diagnosed with embryonic abortion, it is recommended that abortion be performed under the guidance of a doctor. If the time of embryonic abortion is less than 2 weeks, drug abortion and clearance surgery can be used. If there is no abnormality, oral estrogen can be administered first before performing the procedure. If there is any abnormality, it is necessary to restore the coagulation function before the surgical treatment; 4. miscarriage: if the patient is determined to be pregnant after the blood test, and the miscarriage is caused by external or self factors, the patient will not be able to observe the pregnancy sac during the ultrasound examination. It is recommended to seek medical attention in a timely manner and treat the cause clearly. Generally, pre-eclampsia miscarriage requires bed rest, avoiding sexual intercourse, etc., and can be treated with oral progesterone under the advice of a doctor; complete miscarriage, if the symptoms disappear, generally does not require treatment; inevitable miscarriage, incomplete miscarriage and indolent miscarriage patients need to perform scraping, prostate drugs, etc. During the treatment process, pregnant women bleed excessively and need to stop bleeding and anti-infection treatment in a timely manner The treatment of excessive bleeding in pregnant women requires timely hemostasis and anti-infection treatment. Pregnant women with pregnancy confirmed by urine test or blood test and no gestational sac seen by ultrasound need to be alerted to ectopic pregnancy and abnormal embryo development, and it is recommended to follow the doctor’s advice for the next step of treatment in a timely manner.