Ultrasound tests use high-frequency sound waves to create an internal image of the body. With nuchal translucency ultrasound tests, the scan is carried out on pregnant individuals as part of the first-trimester screening tests, and we use an extremely advanced ultrasound system for more precise results. A nuchal translucency ultrasound tests for the statistical likelihood of chromosomal disorders. This test is a helpful tool used to reassure expectant parents that the baby is in good health.

What is Nuchal Translucency?

In the base of the neck of the fetus is the nuchal fold, which is where nuchal translucency fluid is stored. If this fluid is thicker than in typical measurements, this could indicate a higher risk of Down’s syndrome (trisomy 21), Patau’s syndrome (trisomy 13), or Edward’s syndrome (trisomy 18).

How is a Nuchal Translucency Test Conducted?

A nuchal translucency ultrasound test is a non-invasive scan.

The ultrasound wand–which is connected to the ultrasound machine–is dragged along the tummy of the mother-to-be to create an image of the baby. Sometimes, depending on the position of the womb and the baby, the transvaginal method is used to get a better view of the fetus. This test poses no risk to the baby and should not be uncomfortable.

During the test, the sonographer will measure the length of the baby from crown to rump (CRL) to assess the gestational age of the fetus. Next, the sonographer will measure the thickness of the fluid in the nuchal fold (at the back of the neck). With these measurements, along with the age of the mother and the maternal hCG and PAPP-A levels, the sonographer will calculate the probability of any chromosomal disorders.

The nuchal fluid becomes thicker as the pregnancy advances, which is why the scan should be conducted between 11+1 and 13+6 weeks of the pregnancy for the best results.

What Does a Nuchal Translucency Ultrasound Test Determine?

As mentioned above, the test will gather information pertaining to potential chromosomal disorders. These are disorders such as Down’s syndrome (Trisomy 21), Edward’s syndrome (Trisomy 18) and Patau syndrome (Trisomy 13). In these instances, the fetus has an extra chromosome, be it chromosome number 21, 18 or 13.

As this is a screening test, alone this test does not offer definitive results but rather a statistical likelihood of such disorders. For example, you will be told that your baby is low or high risk for Down’s syndrome. When paired with typical first-trimester screening, the results are 83% to 92% accurate. If the sonographer notices that the nuchal translucency fluid is thicker than in most cases, they may suggest the mother undergo further testing for definitive results.

What Other Tests Can be Conducted?

The nuchal translucency ultrasound is popular because it is non-invasive, but in the event your baby is high risk for Down’s syndrome, further tests are required. The sonographer may suggest either a chorionic villus sampling (also known as a CVS) or an amniocentesis ornon-invasive prenatal testing (NIPT). CVS and amniocentesis carry a slight risk – 0.5% to 1.0% – of miscarriage because of their invasive nature. Before making the decision to proceed with one of these invasive tests, it may be worthwhile considering an NIPT. NIPT is a blood test which can look for free-fetal DNA in your maternal blood stream. The lab can further determine whether your baby is at risk for Down’s syndrome and this information can be invaluable when making a decision to proceed or not with invasive testing.

At OMNI, our sonographers are accredited by the Fetal Medicine Foundation to conduct nuchal translucency ultrasounds. For advice, information or to book your ultrasound, get in touch with us today.

OMNI Ultrasound & Gynaecological Care

Condous performs Advanced Endosurgery procedures for women needing intervention for pelvic masses, adnexal pathology, severe endometriosis or hysterectomy. He also runs ‘Hands on’ Live Sheep Laparoscopic Workshops for gynaecologists at Camden Veterinarian School.
Having completed an undergraduate degree with the University of Adelaide, he left Australia in 1993 and moved to London where he completed his training in Obstetrics and Gynaecology. From 2001 to 2003 Condous worked as a Senior Research Fellow at St George’s Hospital, London. At St George’s he set up the Acute Gynaecology Unit, the first in the United Kingdom. It was also during this time that he developed an interest in Early Pregnancy and especially the management of pregnancies of unknown location (PULs). Condous has developed many mathematical models for the prediction of outcome of PULs which have been featured in numerous peer review journals. In 2005, he returned to Australia where he completed his Laparoscopic Fellowship at the Centre for Advanced Reproductive Endosurgery, Royal North Shore, Sydney.

Condous was appointed as a Consultant Gynaecologist and Senior Lecturer at Nepean Hospital in 2006 and soon was made Associate Professor. In 2010, he was made Departmental Head of Obstetrics and Gynaecology at Nepean Hospital. He obtained the MRCOG in 1999 and was made FRANZCOG in 2005. In 2009, he was awarded his Doctorate in Medicine (MD), University of London, for his thesis entitled: “The management of pregnancies of unknown location and the development of new mathematical models to predict outcome”.

Condous has edited three books including the “Handbook of Early Pregnancy Care”, published over 100 papers in international journals and is internationally renowned for his work in Early Pregnancy. He is the Associate Editor for Gynaecologic Obstetric Investigation, which is a European based journal, as well as the Australasian Journal of Ultrasound in Medicine (AJUM). He is on the organising committee and is an invited speaker at the International Society of Ultrasound in Obstetrics and Gynaecology (ISUOG) Scientific meeting in Sydney 2013. His current research interests relate to the management of ectopic pregnancy, 1st trimester growth, PULs and miscarriage and the use of transvaginal ultrasound (in particular sonovaginography, to predict posterior compartment deep infiltrating rectovaginal endometriosis).Condous is also actively involved with post-graduate education including the annual running of the Early Pregnancy and Gynaecological Ultrasound Interactive Courses for Sonologists, Radiologists, Sonographers and Gynaecologists in Australia.