What is a dating ultrasound
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.Most parents look forward to their scan because it gives them the first glimpse of their baby.You will probably be give you a printout of your baby by the sonographer as a keepsake, it is important to remember the main purpose of the scan.Very high frequency sound waves of between 3.5 to 7.0 megahertz (i.e.3.5 to 7 million cycles per second) are generally used for this purpose.They are emitted from a transducer which is placed in contact with the maternal abdomen, and is moved to "look at" (likened to a light shined from a torch) any particular content of the uterus.Repetitive arrays of ultrasound beams scan the fetus in thin slices and are reflected back onto the same transducer.
Before the advent of routine ultrasound in pregnancy, medical personnel estimated a baby’s due date by the date of the last menstrual period and by feeling the uterus and determining the size to see if it matched the given due date.
Such measurements form the cornerstone in the assessment of gestational age, size and growth in the fetus.
A registered nurse with more than 25 years of experience in oncology, labor/delivery, neonatal intensive care, infertility and ophthalmology, Sharon Perkins has also coauthored and edited numerous health books for the Wiley "Dummies" series.
Normally, ultrasounds before until week 4 of pregnancy shows nothing in the uterus and serve no purpose.
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.
The person performing the scan is called a sonographer.