How accurate are nhs dating scans

How accurate is a dating scan?

How accurate are dating scans? A dating scan is the most accurate way to predict your due date, also known as your estimated date of delivery (EDD). The point of the scan is to work out how many weeks pregnant you are. You may have calculated the length of your pregnancy from the first day of your last menstrual period (LMP).

When will I have a dating scan appointment?

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 you’ll have, so it’s likely to be a significant moment for you. Youll only have a scan before 10 weeks in certain situations.

What happens if my scan date is different?

If the scan date differs from your last period dates, the scan date will be used. The scan will usually show that your pregnancy is less far along than suggested by your LMP. This means that accurate dating reduces your chance of having your labour induced because your baby is thought to be overdue.

How is Downs syndrome diagnosed at a dating scan?

Screening for Downs syndrome will happen at the dating scan if: the scan takes place between 10 and 14 weeks of pregnancy The screening test for Downs syndrome used at this stage of pregnancy is called the combined test. It involves a blood test and measuring the fluid at the back of the babys neck (nuchal translucency) with an ultrasound scan.

How accurate is a scan date?

A scan date is normally spot on although if theres a few days difference between the scan date and your date they will go with your dates. I think mine was spot on, 12 weeks 2 days was actually 11w6d which I agreed with but they are not infallible. Doesnt really make any difference as my daughter was 3 weeks early.

When will I have a dating scan?

Youll have a dating scan, also known as a 12-week scan between about 10 weeks and 14 weeks of pregnancy. For most mums-to-be, this is their first scan (NICE 2008, Newson 2014). Youll only have a scan before this, between six weeks and 10 weeks, if youve experienced bleeding, pain, or problems in a previous pregnancy (Miscarriage Association nd).

Are dating scans more accurate than LMP?

(I already have twins) ps Congratulations! i meant to add: dating scans are more accurate than LMP, as you can ovulate any time in cycle... (although certain days are more likely) and sperm can hang about 7 days... Being pregnant can give a positive result on an ovulation test because the hormones are similar chemically (as I understand it).

How accurate are early scans at 12 weeks?

Early scans can be out by 5 days or so but I thought by 12 weeks they were regarded as fairly accurate. 3 weeks is a big difference! I dont think they would be that far out. Perhaps you ovulated twice that month? I was sent to EPU as was being very sick. By my dates I was 7 weeks, by theirs I was 6 weeks.

How accurate are dating scans? A dating scan is the most accurate way to predict your due date, also known as your estimated date of delivery (EDD). The point of the scan is to work out how many weeks pregnant you are. You may have calculated the length of your pregnancy from the first day of your last menstrual period (LMP).

What are the tests for Downs syndrome?

There are two basic methods of screening for Downs syndrome - the ultrasound scan and biochemical serum screening: Nuchal translucency ultrasound scan (also called the NT scan): this is a special ultrasound scan that is done between 11 weeks and 2 days and 14 weeks and 1 day of pregnancy.

How is the risk of Downs syndrome determined?

Again, a computer program is used to give the risk of the baby having Downs syndrome, based on the blood test results, your age, the stage that you are at in your pregnancy, and your weight, ethnicity and smoking status. The quadruple test is not as accurate as the combined test and does not screen for Edwards syndrome and Pataus syndrome.

How can you tell if someone has Down syndrome?

While these screenings can be helpful, the only way to definitively diagnose Down syndrome is to get a diagnostic test.

Can Down syndrome be diagnosed with a negative ultrasound?

While imaging tests can help indicate the possibility of Down syndrome, they cannot confirm it. Likewise, a negative test does not rule out Down syndrome. This specialized ultrasound, which is performed at 11 to 13 weeks, measures the thickness of an area of tissue at the back of a fetuss neck called the nuchal fold.