Can dating scans give wrong dates
Ask your GP if you want the reassurance of an early scan. The scan's main purpose is to work out accurately how many weeks pregnant you are and estimate your due date.You may have calculated the length of your pregnancy from the first day of your last menstrual period (LMP).
If she estimates your measurements are off by three weeks or more, in many cases she may move the due date to reflect this.For instance, if your period starts on the 5th April, then your estimated due date for delivery is the 12th January.The dating scan is an ultrasound scan that can be done as early as six weeks after the last period, but the dating scan will be most accurate when done between 8 and 12 weeks gestation.I prefer to do the dating scan via the transvaginal approach at approximately 8 weeks gestation.This is normally done in the consulting room for a small out of pocket cost.It's amazing to see the little blob with a heartbeat that will soon become your baby.
For most mums-to-be, the first scan will be a dating scan at between 10 weeks and 13 weeks plus six days of pregnancy.
Between week 14 and week 22 of pregnancy, your doc likely ordered a blood test to screen for AFP — short for Alpha fetoprotein, a protein that’s normally produced by the liver and yolk sac of your still-developing bambino; levels vary widely throughout your pregnancy.
(This is often part of the triple screen.) While high levels of AFP sometimes indicate a potential genetic abnormality, the number one reason is simply your due date was miscalculated.
You may also be offered an early scan if you've had a previous miscarriage.
Not all units offer an early scan if all is going well in this pregnancy, though.
Traditionally the last menstrual period has been used to date a pregnancy, but this may be highly inaccurate.