The scan

This takes about 20-40 minutes, although longer under some circumstances. You do not need to have a full bladder. If you are uncertain of the date of your last menstrual period, it is recommended that you have a dating scan prior to the Nuchal scan. We will measure the thickness at the back of the baby's neck down to a tenth of a millimetre.

Blood tests

We ask for these in advance so that we can have the blood result and therefore give you the full result at the time of your appointment and discuss the implications. These can be taken at any time from 10 to 13 weeks. We will send you a special pack with simple instructions at the time you book the scan. Provided the blood is sent 48 hours before the scan we will usually have the result in time.

Blood can be taken on Level 1 of the Women's Centre at the John Radcliffe; or it can be taken by your midwife or at your doctor's surgery if you have checked with them first.

Once your blood has been taken, you should put it in the stamped addressed pack and post it the same day as it is taken. We advise that blood is not taken on a Thursday or Friday because of postal problems. You do not need to contact us to ensure the blood result has arrived: we will normally contact you if it has not.