What Are Different Types of Prenatal Ultrasound Screens?
Prenatal screening can be an important part of prenatal care. It can help detect specific health conditions in a baby before they are born. Your healthcare provider may recommend several screening tests during your pregnancy, each of which can help provide important information about your baby's health. Learn more about the different types of prenatal screening tests available and what they can offer expectant parents here.
Ultrasound scans, also called sonograms, use sound waves to create images of a baby inside the uterus. They can provide detailed information about a fetus's physical development and the anatomy of the pregnant person’s ovaries, uterus, placenta, and cervix. Your ultrasound technician (also called a sonographer) will likely use a transvaginal ultrasound probe for any ultrasounds performed early in pregnancy, while an abdominal ultrasound is typically performed for ultrasounds completed at around 10 weeks gestation and beyond.
Imaging techniques such as ultrasounds can detect certain problems with organ structure and function. However, ultrasound is not able to examine a baby’s chromosomes or genetic material, as this information is not visible through sonographic techniques.
Nuchal Translucency Sonogram
The nuchal translucency (NT) sonogram test is an ultrasound screen offered at the end of the first trimester of pregnancy. A sonographer who has completed specialized training will carefully measure the fluid-filled space at the back of the fetal neck. While all babies will have this fluid-filled space (“nuchal translucency”), the presence of extra fluid in this space can be linked to heart problems and potentially chromosomal or other genetic conditions in the baby. The NT sonogram is usually performed between 11 weeks 0 days gestation and 13 weeks 6 days gestation. Typically, the results of the NT sonogram’s measurement will be available on the same day as the exam or as soon as the authorizing physician reviews the images and finalizes the ultrasound report.
If your doctor has recommended you complete the combined first-trimester screen, your NT sonogram will likely be accompanied by a blood sample collection. The combined first-trimester screen results are typically available within one week of the blood sample collection.
Although the NT sonogram can be a very useful tool in the early identification of certain fetal abnormalities and genetic conditions, it may not be performed in every pregnancy. Some OB offices may not have a sonographer trained and certified to perform NT sonograms, meaning their patients might have to travel some distance in order to have this examination.
In some cases, health insurance policies may only cover a few ultrasound scans during pregnancy – so you’ll want to talk to your doctor about which ultrasounds are most important for your prenatal care. Furthermore, since a blood screening test called non-invasive prenatal screening (NIPS, also called “NIPT”) is proven to reliably screen pregnancies of all risks for certain common chromosome conditions, your prenatal care provider may present the NT scan as entirely optional if you’ve already received low-risk NIPS results by the time this ultrasound would be performed.
The anatomy sonogram is an ultrasound screen recommended in all pregnancies to detect physical differences that may be called “soft markers,” birth defects, or structural anomalies – depending on what is found. This ultrasound examination is usually performed at around 20 weeks gestation, but some doctors may recommend scheduling the appointment earlier, such as 16 or 18 weeks. In general, the earlier the anatomy sonogram is performed, the higher the chance that the exam may be “incomplete,” as the baby is simply smaller at this time.
However, early screening can allow for earlier identification of fetal anomalies, thereby offering greater options for potential interventions. For example, an anatomy sonogram at 16 or 18 weeks may reveal spina bifida (an opening along the baby’s spine), prompting a referral to a fetal therapy center where parents can consult with a specialist about the possibility of in utero fetal surgery to close the defect. Birth defects like spina bifida cannot be identified with chromosomal screening tests like NIPS, so even if you’ve already had normal NIPS results, the anatomy sonogram will be a standard recommendation for your prenatal care.
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