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

Is 12 week scan a dating scan?

Youll have a dating scan appointment, also known as a 12-week scan, between about 10 weeks and 14 weeks of pregnancy. This is usually the first scan youll have, so its likely to be a significant moment for you. Youll only have a scan before 10 weeks in certain situations.

Can you see birth defects at 12 week scan?

NT was increased in 12/23 (52.2%) cases of structural anomaly detected at the early scan. Of the 12 cases of heart defects, four (33.3%) were detected at the early scan, five (41.7%) at the 20-week scan and three (25.0%) after birth.

What defects can a 12 week scan show?

Estimate individual risk for Down syndrome and other chromosomal abnormality. Screen for spina bifida. More accurately date the pregnancy. Diagnose multiple fetuses.

Can ultrasounds be off by 2 weeks?

As pregnancy progresses, the accuracy of an ultrasound for predicting due dates decreases. Between 18 and 28 weeks of gestation, the margin of error increases to plus or minus two weeks. After 28 weeks, the ultrasound may be off by three weeks or more in predicting a due date.