How accurate are nhs dating scans
I went for my morphology scan yesterday (supposed to be 19 wks 4 days) and it turns out that Im only 16 wks 3 days???Now I must explain that because I knew the exact date of my LMP, the GP said that I did not need an early dating scan and was not offered one.However, the accuracy of the ultrasound examination is always dependent on the skill of the sonographer and the quality of the equipment.Usually the expected date of delivery (EDD or EDC) is calculated from your last menstrual period - if the early dating scan calculates the EDD to be within 5 days of the EDD from your last menstrual period.Sometimes a trans-vaginal examination shows that your pregnancy is less advanced than expected.
If the pregnancy is very early the gestation sac and fetus will not be big enough to see, so the transvaginal approach will give better pictures.
Find out more about the combined screening test for Down's syndrome.
You won't be offered the combined screening test if your dating scan happens after 14 weeks.
The person performing the scan is called a sonographer.
You may need to have a full bladder for this scan, as this makes the ultrasound image clearer.