Different Types of Ultrasound Exams During Pregnancy

03/02/2018

You may know sonograms are special ultrasound procedures which use sound waves to assess your baby’s body structures, or that these procedures emit zero radiation and are typically non-invasive. However, did you know that there are many different types of sonograms used to monitor your baby’s development during pregnancy?

Hopefully, after reading this blog you will feel more comfortable before your next ultrasound appointment and you’ll enjoy the experience.

Dating Scan (Transvaginal Scan)

Often performed around the 5-8-week stage of pregnancy, the dating scan is performed to examine the woman’s uterus, ovaries, cervix, and vagina. Typically, the exam begins as a topical scan with an optional transvaginal scan used to better visualize the structures. With your consent, the transvaginal scan is performed by inserting a special probe inside the vagina and is usually used in the early stages of a pregnancy to help diagnose potential ectopic or molar pregnancies. Additionally, transvaginal scans provide a better view of the uterus compared to a topical scan in the early stages of pregnancy.

Nuchal Translucency (NT) Sonogram

The Nuchal Translucency (NT) scan is usually the second scan conducted during a pregnancy, around 11-13 weeks plus six days of pregnancy. Your sonographer will use the NT scan to assess a collection of fluid under the skin on the back of your baby’s neck. All babies have some nuchal translucency behind their necks, but many babies with Down’s syndrome have an increased amount. Therefore, the main purpose of an NT scan is to try and detect genetic disorders such as Down’s syndrome. The NT scan will be performed abdominally, and the sonographer will also measure the approximate growth of your baby, their heartbeat, and brain formation.

Anatomy Scan

The Anatomy scan is performed half way through your pregnancy, assessing the development of your baby’s organs and body to make sure the gestational age is still on pace for your delivery date. This ultrasound exam is typically one of the more memorable experiences for parents because they get an in depth look at their baby. During the Anatomy scan, the baby is measured from crown to rump as well as around its belly and head. The scan also looks at other main organs such as the heart (and its four chambers), brain, spine, stomach, kidneys, bladder, and sex organs.

This sonogram typically takes 30-45 minutes and at the end of the scan, a gender can usually be identified. However, it is important to note that certain factors can complicate the identification of your baby’s sex, including the stage of the pregnancy as well as the position of the fetus inside the womb. Although science allows us to make an educated guess about your baby’s gender, we will never be 100% certain until child birth.

Growth Scans

Growth scans are used to determine your baby’s size and amniotic fluid volume. These scans are typically done during your third trimester (28 to 32 weeks), assuming you are not a high-risk pregnancy. To estimate the size of your baby, the sonographer will measure the baby’s head (Biparietal diameter across the head and head circumference), the abdominal circumference, as well as the length of the longest bone in the leg, typically the femur (thigh bone). This information can help determine if the baby is an average size or weight, or how much above or below the average.

Doppler Blood Flow

Doppler Ultrasound exams are non-invasive scans that measure the blood flow through vessels by bouncing sound waves off circulating red blood cells. Normal ultrasound scans show an image of the baby, whereas a Doppler ultrasound can help show the specific amount of blood flow to the baby (indicating how much oxygen and nutrients are being supplied). Your doctor may order a Doppler ultrasound to help examine your veins and arteries, watching for blood clots, placental problems, decreased blood circulation, possible cord compression or narrowing of an artery. There are three types of Doppler scans; Continuous Wave Doppler, Duplex Doppler, and Colour Doppler. The scans can be completed at any point during your pregnancy and typically depend on patient history and health conditions.

In Conclusion

As an expecting parent, the next nine months will likely be a rollercoaster of emotions. Remember that all ultrasound scans are medical exams and require your utmost cooperation. Therefore, please try saving your questions until the end of your exam, so your sonographer can focus on conducting the scan to the best of their ability. At the end of the day, don’t forget these scans provide a window into your baby’s world as they grow and develop; enjoy these special moments with your spouse as you prepare to start or expand your family.