how long does the nt ultrasound take
5. The nuchal translucency is measured by carrying out an abdominal ultrasound scan from 11 weeks 4 days of foetal age to 13 weeks 6 days. You will be asked to lie on an examination couch.our doctor would recommend a nuchal translucency scan: 1  to confirm the exact date of the pregnancy and the due date; 2  to confirm the number of foetuses (single or multiple); 3  to confirm that the foetus is growing appropriately and appears to be developing normally;