Dating changes for smaller discrepancies are appropriate based on how early in the first trimester the ultrasound examination was performed and clinical assessment of the reliability of the LMP date Table 1. Whatever you are going through, you are not alone. Ameri-can College of Obstetricians and Gynecologists. Comments Please read our Chat guidelines. Definition of term pregnancy. Due date 17 jun according to scan and 7 jun by lmp. This Internet site provides information of a general nature and is designed for educational purposes only.


How confusing for you. I asked the sonographer if that sort of difference is usual and she asked if I had been on the pill, I came off in Jan and she mentioned its common for the ovulation to be delayed and dates different. But two weeks is a fair bit more deviation. Did you ask her about it? Or did the sonographer mention anything about the big change in DD? It is confusing your BFP date being pre-conception Is it possible you just a small bub? Two weeks will drive you crazy. Good luck. Thank you so much for all your answers!! The sonographer just said that you can ovulate at different times during your cycle and that's why the ultrasound due date can differ from the LMP due date. I think maybe the bubs is just a bit smaller at this stage, I could maybe understand it being off by maybe a week but not the 2 that she thinks. I'm going to just try and relax and go with the flow easier said than done lol and see what happens at the next scan.

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 transducer and a fullish bladder. If the pregnancy is click the following article dating scan different to lmp the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures.

Dating scans are usually recommended if there is doubt about the validity of the last menstrual period. By 6 to 7 weeks gestation the fetus is clearly seen on trans-vaginal ultrasound and the heart beat 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. Ultrasounds performed during the first 12 weeks of pregnancy are generally within 3 - 5 days of accuracy. The most accurate time is between 8 and 11 weeks gestation.

This is because the fetus is growing so quickly that there is a click the following article difference in size from week to week. However, the accuracy of the ultrasound examination is always dependent on the skill of the sonographer and the quality of the equipment.

The EDD from the early dating scan is used dating scan different to lmp 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. Ultrasound examinations from 12 to 22 weeks are regarded as being within 10 days of accuracy or up to 10 days earlier or 10 days later than the woman's calculated due date. Ultrasounds performed after 22 weeks gestation dating scan different to lmp be used to estimate the due date of the baby because the size no longer reflects the age very well.

Even average babies can differ by up to 2 to 3 "weeks of growth". These scans are only used to estimate the due date of your baby if this is all you have to go on. If you have more than one ultrasound during your pregnancy, giving you 'multiple dates', then the earliest ultrasound estimate should be used, because it will be more accurate. If you have any questions about this, please feel free to talk to your sonographer or doctor about it.

Make An Appointment. Find Us. We know you may have c oncerns about Coronavirus. We are open during this period. Find out what we are doing to help protect our patientstheir families and the wider community. More Info. No one logged in. Dating and viability What is a dating scan? Dating scans also reveal other important information such as: the number of fetuses and gestation sacs the presence of a heart beat the size of the fetus, from which the gestational age is estimated unusual features of the uterus such as the shape or the presence of fibroids How is it done?

For transvaginal ultrasound you can have an empty bladder When is it recommended? For example if you do not know click to see more the first day of your last period, or the likely day of conception was have had irregular periods have had an unusual cycle because you recently stopped the oral contraceptive pill, or you recently had a miscarriage, or you are breast-feeding had some implantation bleeding which can be been confused with your last period date What can be seen?

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.

How accurate is the ultrasound examination? The earlier the ultrasound is done, the more accurate it is at estimating the baby's due date.

Also the fetus cannot bend and twist too much yet, so the length of the body is fairly constant. The scan or my dates - which should Here believe?

As the baby gets bigger, it starts to express its individual growth potential. The visit web page of the baby correlates less and less with its age as time goes on.

You can estimate the due date of the baby by using our pregnancy calculator. What can be seen?