Last menstrual period ultrasound dating transvaginal
Sometimes a trans-vaginal examination shows that your pregnancy is less advanced than expected.
Pregnancy is dated from the first day of the last menstrual period, so at four weeks, a woman is just due for a menstrual period.
Seeing the gestational sac, which looks like a black dot in the uterus, has several benefits: it confirms that a woman is pregnant, confirms that the pregnancy at a very early stage, making dating the pregnancy very accurate, and also confirms that the pregnancy is in the uterus rather than ectopic, or outside the uterus.
A yolk sac, the early source of nutrients for the embryo is seen around 5.5 to 6 weeks.
The embryo still can’t be seen at all at this early stage.
By 6 to 7 weeks, it’s usually possibly to see the fetal pole, the earlier sign of the developing embryo, within the gestational sac on transvaginal ultrasound.