THE 11-13+6 WEEK (“The Nuchal Translucency”) SCAN

This provides important information about your pregnancy. It is usually performed transabdominally but occasionally a transvaginal scan will be required to provide all the information.

Scanning at this gestation is to:

Confirm the viability of a pregnancy

At this gestation although the majority of pregnancies will be normal, a small number will result in early pregnancy loss

Confirm the gestational age

Accurate dating of a pregnancy is particularly important for women unsure of their menstrual cycle or those with irregular cycles.

Diagnose multiple pregnancy

This may be present in up to 2% of pregnancies at this gestation, and is even more common if ovulation induction has been undertaken. This is the best gestation to determine whether or not twins share a placenta (chorionicity) which has a major impact on the management of the pregnancy.

To screen for chromosomal abnormalities (combined nuchal-biochemistry test)

Although most babies are normal, all mothers have a risk of having a baby with a chromosomal anomaly including Down syndrome. Measurement of the nuchal translucency (i.e fluid behind the neck of the baby), together with knowledge of the mother’s age and measurement of the maternal hormones BhCG and PAPP-A will allow estimation of the mother’s individual risk. Mothers with a high predicted risk (usually 1:300 or greater) may then decide if they wish to have diagnostic testing (amniocentesis or chorion villus sampling).

Diagnose major structural abnormalities

A number of major fetal abnormalities including severe forms of spina bifida and diaphragmatic hernia may be diagnosed at this gestation. However, we recommend a detailed fetal anatomy scan at 20-23 weeks for optimal detection of fetal anomalies.