12 Week Nuchal Translucency Scan and Blood Test
The 12-week pregnancy ultrasound scan, or nuchal scan, is the first routine scan of pregnancy. You can have this pregnancy scan in London in our private clinic as a one-off or as the start of an ongoing relationship where we will offer diagnosis and support throughout your pregnancy.
The 12-week pregnancy screen and scan is used to:
The first trimester screening scan allows a close assessment of a baby's anatomy and organs and can detect abnormalities that may be linked with Down syndrome or other major types of birth defects. In most cases it is a confirmation that things are progressing normally; infrequently, this scan highlights an issue that requires closer observation.
The nuchal scan needs to be performed between 11 weeks + 5 days and 13 weeks + 5 days into your pregnancy.
The results of the scan are combined with other information including maternal age and personal history and results from a blood test that checks two specific proteins (free beta HCG and PAPPA); this is the first trimester “Combined Screen” which is routinely used to calculate the risk of certain abnormalities.
What to expect during a 12 week pregnancy scan We allow an hour for the appointment so that you do not feel rushed and will have adequate time to ask questions. You'll be welcomed by our prenatal sonographer or by our doctor who specialises in prenatal diagnosis, who will go through your personal medical history.
The scan takes around 30 minutes. A probe is passed across the skin of your abdomen and as this happens images will appear on screen. Your sonographer will talk you through the images and point out aspects of your baby's anatomy. He or she will explain what these imply in terms of your risk level for Down syndrome and other congenital abnormalities.
After your appointment, we will send you a secure link where you can view and download a selection of images from your scan.
If you have not already had a sample of your blood taken, this will take a few minutes. We'll have your blood test results within 24 hours and will combine these with the results from your scan. Your sonographer or doctor will explain them in more detail and let you know what you need to do next.
We'll also send a report to your doctor within 24 hours. We will give you a copy of your report shortly after your appointment, or we can send it by email. In the unlikely event that the scan or blood test reveals anything of concern the sonographer will telephone your doctor immediately.
Testing for Down syndrome During the ultrasound scan the sonographer measures the fluid beneath the skin at the back of your baby's neck - known as the nuchal translucency. This measurement is combined with other information to estimate the risk of Down syndrome.
The blood test, which you may have any time after 10 weeks or on the same day as your scan, is used to measure the levels of two hormones in your blood, which provide another indication of risk of having a baby with Down syndrome. Although the blood test is optional we recommend it as it increases the accuracy of this test. Ultrasound is 70% accurate but increases to 90% when combined with the blood test.
If your risk level is high Our ultrasound specialists are extremely experienced in performing scans for women in pregnancy and take time and great care to explain what is happening. If your ultrasound scan indicates a risk of abnormal development your sonographer will answer your questions and explain the context. The test can only provide an indication of risk and there are further tests that offer a more accurate assessment.
You may wish to have one of the Non Invasive Prenatal Tests that we offer at The Medical Chambers Kensington. These allow a close analysis of foetal chromosomes as a screen for genetic abnormalities, and require a simple blood sample taken from your arm, so it is perfectly safe. The MaterniT21 PLUS Test, MaterniT GENOME and Harmony Prenatal Test are highly accurate, with results taking a maximum of 5 to 7 day. For more information on these, please follow the links above.
Invasive tests such as chorionic villus sampling (CVS) or amniocentesis are usually not required, but some parents do wish to have these when clarification is sought. These involve the insertion of a fine needle to draw cells from the amniotic fluid surrounding a baby (in the case of amniocentesis) or from the chorion, or the sheath surrounding the amniotic sac (in the case of chorionic villus sampling). The chromosomes in these cells can then be analysed. These tests are highly accurate but they do carry a small risk to the pregnancy. We do not offer these tests at The Medical Chambers Kensington.