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With an average gestation period of about 40 weeks, you may have three or more ultrasounds during your pregnancy. These exams help your doctor confirm your pregnancy and expected due date, and provide information that helps them monitor the health of you and your baby.
Obstetrical ultrasounds can be requested at a variety of points during your pregnancy. However, there is one type of obstetrical ultrasound that is especially time sensitive. Based on your age and other potential risk factors, you and your doctor may discuss the need for this type of diagnostic testing. If you both agree that it’s appropriate, a nuchal translucency ultrasound must be performed in your first trimester, when you are between 11 weeks and 13 weeks and six days pregnant.
This exam is also known as a nuchal translucency screening test. During this exam, a trained Mayfair Diagnostics sonographer will use sound waves to examine your baby. Mayfair sonographers are certified as nuchal translucency sonographers through the Fetal Medicine Foundation.
First, they check the gestational age of your baby by measuring your baby from top to bottom, recording the crown-rump-length (CRL). Then, they will examine and measure an area at the back of the fetus’ neck, called the nuchal translucency.
The measurements from this test, including the crown-rump length, fetal heart rate, and nuchal translucency thickness are combined with the age of the mother and certain other factors to determine the chance that the fetus may have a certain condition. This can include Downs Syndrome, other chromosomal abnormalities or heart problems. Additional diagnostic tests, such as chorionic villus sampling (CVS) or amniocentesis, may also be ordered by your doctor for a more definitive answer.
Ultrasound imaging is non-invasive and doesn’t use radiation. It has been used to evaluate pregnancy for nearly four decades and there has been no evidence of harm to the patient, embryo, or fetus. However, it should only be performed when medically necessary.
Ultrasound imaging provides a clear picture of the uterus and provides much information about your pregnancy. It may be temporarily uncomfortable but shouldn’t be painful. And while they can offer reassurance about your baby’s health, we do understand that they can also cause anxiety.
Once your doctor has identified the need for this ultrasound, your doctor’s office may book an appointment for you, or provide you with a number to call to book your appointment. You will also be given a requisition form and preparation instructions for your exam.
For a nuchal translucency ultrasound, you will need to arrive for your exam with a full bladder. A full bladder helps the sonographer to see your cervix and positions the uterus, so we are better able to see your baby.
Once in the exam room you may be asked to change into a gown and then be positioned by one of our compassionate and experienced sonographers. A warm, unscented, hypo-allergenic, water-based ultrasound gel will be applied to your abdomen, and your sonographer will move the transducer around the front and side of your abdomen to gather images. You may experience mild pressure while the sonographer takes the images.
Obstetrical ultrasounds generally take between 25 and 40 minutes, but this may vary depending on how much your baby moves and its position. Your sonographer will try to ensure your comfort while also acquiring accurate measurements and the best possible images for you and your doctor.
Measuring your baby during any obstetrical ultrasound can be challenging and requires concentration, so your sonographer will usually show you images of your baby towards the end of your exam. We can also save images of your baby on a complimentary USB, to share with family and friends. You would need to speak with one of our clinic receptionists for more details.
Mayfair Diagnostics has 11 locations in Calgary, one in Cochrane, and one in Regina, which provide ultrasound services.
de Bellefonds, C. (2022) “Nuchal Translucency Screening.” www.whattoexpect.com. Accessed March 22, 2022.
Healthwise Staff (2021) “Nuchal Translucency Screening Test.” www.myhealth.alberta.ca. Accessed March 22, 2022.
U.S. Department of Health and Human Services, National Institutes of Health (2022) “Nuchal translucency test.” www.medlineplus.gov. Accessed March 22, 2022.