What is a dating and viability ultrasound
In very early pregnancy, the embryo and pregnancy sac may simply be too small to see very much at all.
But with every day which passes, the embryo becomes bigger and more advanced in its development.
When a transvaginal ultrasound is done at seven weeks gestation, the transducer is placed in the mother’s vagina and the sound waves are transmitted via her cervix and directly into the uterus.
With this form of scan it is not as necessary for the mother to have a full bladder.
There are two ways of having a seven week ultrasound.
One is via the abdomen – transabdominally and the other is through the vagina – transvaginally.
In some respects the seven week ultrasound can be quite accurate because the embryo is developing very quickly.
They are also not as mobile and active as they will be with future development.
This can be for many reasons but the most common is to confirm pregnancy and to check that the embryo is viable and “everything’s ok”.It is also impossible to do a thorough foetal screening assessment because it is still just too premature in terms of embryonic development.However, general “mass” structures such as a head and body can generally be seen in the embryo at seven weeks.When having a transabdominal ultrasound, however, a full bladder is necessary in order to “lift” the uterus up and out of the pelvis so the embryo can be seen more clearly.Later on as the pregnancy progresses, a full bladder is not necessary as the enlarging uterus is no longer contained in the pelvic rim.