A dating scan is an ultrasound examination which is performed in order to establish the gestational age of the pregnancy. Most dating scans are done with a trans-abdominal ultrasound and a fullish bladder.
If the pregnancy is very early the gestation sac and embryo will not be big enough to see, so the transvaginal approach will give better ultrasound. For transvaginal ultrasound accuracy can have an empty bladder.
By 6 to 7 weeks gestation the developing baby is clearly seen on trans-vaginal ultrasound and ultrasound heartbeat can be seen at this early stage 90 to beats per minute under 6 to 7 weeks, then to beats per minute as the baby matures.
CLINICAL ACTIONS:
By 8 weeks gestation the baby accuracy its heartbeat can be detected relatively easily with trans-abdominal and trans-vaginal examination. This is presuming that the pregnancy is actually at this stage of development. Sometimes a trans-vaginal examination shows that your pregnancy is less advanced than expected. Ultrasounds performed during the first 12 weeks of pregnancy are generally within 5 days of accuracy. The most accurate time is between 8 and 11 weeks gestation.
This is because the baby is growing so quickly that there is a big difference in size from week to week. Also, the baby cannot bend and twist too much yet, so the length of the body is fairly constant at these gestations.
Continuing Education Activity
However, the accuracy of the ultrasound examination is always dependent on the position of the uterus, how much tissue the probe needs to penetrate, the size of the baby, the skill of the sonographer and dating quality scan the equipment. This is why at Ultrasound Care we use the latest equipment, and all our scan are highly skilled.
If the last menstrual period is not known or is unreliable, or the dating scan differs from the last menstrual period dating by more than 5 days the EDD from the early dating scan is used. Bear in mind, that even women with regular 28 day menstrual cycles do not always ovulate on accuracy 14 of the cycle, so your due date may change according to your date of conception.
As the baby gets bigger, it starts to express its individual growth potential. The size of the baby correlates less and less with its age as time goes on. For example, a baby with cm tall parents is likely to be longer than a baby with cm tall ultrasound. Ultrasounds performed after 22 weeks gestation are much less reliable in estimating the due date of the baby because the size no longer reflects the gestational age scan well. These scans are only used to estimate the due date of your baby if this is all you have to go on.
Share via email
If you have any questions about this, please feel free to talk to your sonographer or doctor about this. To assist you in estimating the due date of the baby, please use the Ultrasound Care pregnancy calculator on our website.
Accurate dating scans are important in dating for the delivery of your baby. Ultrasound Care has the most up to date ultrasound technology and our sonographers are highly skilled more info us to provide reliable and accurate dating scans.
Ultrasound Care Privacy. Skip to content. Search Search. Facebook Instagram. Search Close this search box. Pre-Natal Testing. Genetic Services. Genetic Counselling Genetic Carrier Screening. Pregnancy Ultrasounds. Fertility Services. Available Procedures.
Dating Scan
Full Listing of Procedures Performed. Our Commitment to Inclusive Care. Leading the Way in Sustainable Practice Design. Tips for Better Sleep During Pregnancy. Dating Scan.
Publication types
What is a dating scan? Dating scans also reveal other important information such as:. The number of fetuses and gestation sacs and placentas. The presence of a heart beat. The size of the fetus, from which the gestational age is estimated. Features of the uterus such as the shape or the presence of fibroids. How do we do the scan? Why and when is a dating scan recommended? Dating scans may be recommended for women for many reasons including:.
The first day of the last period or the likely day of conception is not known. Women with irregular periods. Women with an unusual cycle, dating aubry babcock hijab recently stopping the oral contraceptive pill, a recent miscarriage, or concurrent breast-feeding. To confirm the fetal heartbeat and viability of the pregnancy.
If a multiple pregnancy is suspected. What can be seen? How accurate is the ultrasound examination? The scan or my dates - which should I believe? Please contact your local Ultrasound Care clinic to arrange for your dating scan ultrasound. We have locations all over Sydney. Quick Links. Open toolbar Accessibility Tools.