Nuchal dating scan
It may show a very minor problem, or something that may get better on its own. onlinelibrary.[Accessed July 2017] Loughna P, Chitty L, Evans T et al. Fetal size and dating: charts recommended for clinical obstetric practice.
As with all screening tests, there can be false-positive and false-negative results. Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies.
The point of the scan is to work out how many weeks pregnant you are. Ectopic pregnancy and miscarriage: diagnosis and initial management CG 154.
This means that accurate dating reduces your chance of having your labour induced because your baby is thought to be overdue.
It shouldn't be uncomfortable, and you don't need a full bladder Your sonographer will give you a report of the scan, which will tell you exactly how many weeks pregnant you are.
Keep it with your maternity notes so your midwife and anyone else involved in your care can see it. This measurement, known as the crown rump length (CRL), is very accurate in the first trimester.
A blood test at what you thought was 13 weeks wouldn't be helpful if you were actually 16 weeks pregnant.
It may lead to you being given a high chance for Down's syndrome, when your baby is actually developing normally (false-positive result). Addition of non-invasive test to improve screening for pregnant women.
As long as the timings are right, you can have the NT scan and blood test at the same appointment as your dating scan. That's because the screening test needs an accurate due date to be reliable.