It is this black space that you will see measured during the ultrasound scan.Currently the most accurate non invasive test for detecting Down syndrome during pregnancy is the measurement of the nuchal translucency with an ultrasound between 11 to 14 weeks of pregnancy.
The top line represents the skin and bottom one, represents the nasal bone.
A third line, almost in continuity with the skin, but at a higher level, represents the tip of the nose.
Accuracy of CRL after 12 weeks in predicting gestational age diminishes and is replaced by measurement of the width of the fetal head (biparietal diameter or BPD).
The nuchal translucency (also spelled nucal translucency) is a collection of fluid beneath the fetal skin in the region of the fetal neck and this is present and seen in all fetuses in early pregnancy.
The 12 week scan is a routine ultrasound examination carried out at 10 to 14 weeks of gestation.
At the first trimester scan they confirm that the fetus is alive, they assess the gestational age by measuring the crown-rump length and will also look for any major problems.
You do not need to have a full bladder, a moderately filled bladder is needed for a proper examination.
Most parents look forward to their scan because it gives them the first glimpse of their baby.
Crown Rump Length: Gestational age = 6 weeks plus (CRL x days).