According
to the consensus of medical experts and actual examination experience, for women with regular menstrual cycles, generally about 35 days after menopause, it is possible to see the gestational sac through vaginal B-ultrasound. However, this is only one
approximate time range, because there are individual differences in the development speed of gestational sac. Detection of the embryo sac may be delayed if the embryo sac develops slowly or if the fertilized egg implants late.
Negative ultrasound has its unique advantages compared with abdominal B-ultrasound, especially in the first trimester:
1. Clear image: The frequency of the negative ultrasound probe is higher and the image is clearer. For expectant mothers with thick abdominal wall fat, clearer images can be obtained.
2. Early discovery: Compared with abdominal B-ultrasound, the yolk sac and embryo are discovered about a week earlier than the abdominal ultrasound, which can verify the gestational age as early as possible and provide more reliable information for later judgment of embryonic development.
3. No need to hold urine: Yin ultrasound does not need to fill the bladder like abdominal B-ultrasound, which reduces the pain of holding urine and the waiting time.
It should be noted that each woman's physical condition and menstrual cycle are different, which will affect the specific time at which the gestational sac is detected. If the menstrual cycle is irregular or ovulation is late, the gestational sac
may appear later.
