Ultrasound dating accuracy early

14-Jun-2019 13:38

At 4.5 to 5 weeks, a gestational sac may be seen in the uterus using transvaginal ultrasound, Joseph Woo, M.

D., explains in "Obstetric Ultrasound: A Comprehensive Guide".

With transvaginal ultrasound, checking for embryonic development known to occur within a certain time frame more accurately dates a pregnancy.

Transvaginal ultrasound can see embryonic development about a week before transabdominal ultrasound, the American Pregnancy Association (APA) states.

This creates error in that the baby will compute out to be further along than he or she really is.

Most babies, except in cases of early IUGR and deformities, grow about the same until 20 weeks or so.

After that, the variations among babies’ measurements cause increasing inaccuracies.

A transducer, a wand-shaped probe, is inserted into the vagina and pressed against the vaginal walls directly next to the uterus.

It records high-frequency sound waves that create an image (see Reference 4).

This creates error in that the baby will compute out to be further along than he or she really is.Most babies, except in cases of early IUGR and deformities, grow about the same until 20 weeks or so.After that, the variations among babies’ measurements cause increasing inaccuracies.A transducer, a wand-shaped probe, is inserted into the vagina and pressed against the vaginal walls directly next to the uterus.It records high-frequency sound waves that create an image (see Reference 4).The femur (thigh bone) length seems to hold on to it’s accuracy longer than the other parameters, but after 36 weeks it isn’t foolproof.