Managing the Unexpected: Prepare for What Prenatal Screening May Reveal
I walk into the consultation room to find my patient with tears falling down her flushed cheeks as she tries to keep from audibly sobbing. Her husband holds her hand and avoids eye contact, looking scared and helpless. She is five months pregnant and just had an ultrasound appointment. They expected it to be filled with joy and to leave with cute ultrasound pictures, but instead they’re filled with fear and despair.
My patient has been dreaming of being a mom since she was a little girl. Now she’s been told that her unborn son has a brain abnormality. “This is every mother’s nightmare,” she thought to herself.
I am a prenatal genetic counselor and I help expectant parents understand findings from prenatal ultrasound and genetic test results. Sometimes, I see expectant parents who received upsetting news. Fortunately, in this case, I am able to tell my patients that there is most likely nothing to worry about.
I sit down and discuss with the couple that we have detected choroid plexus cysts (CPCs) in the baby’s brain. And that the baby is extremely likely to be perfectly healthy. CPCs are almost always what we call “normal variants” or a “soft sign.” These fluid-filled sacs in the brain are not the norm, but they are harmless. They have no impact on the developing brain and usually go away by the time the baby is born. Only in very rare cases, when CPCs are detected along with major birth defects, do we become greatly concerned that the baby has a more severe genetic condition.
Considerations for Prenatal Ultrasounds
It’s not unusual for parents to have the emotional reaction described above when we find something abnormal on an ultrasound. Ultrasounds are medically necessary to determine how far along you are in pregnancy, how many babies you are pregnant with and to check the baby’s heartbeat. Every expectant mother gets one, so parents often forget that an ultrasound also checks for abnormalities.
It is important to recognize that most ultrasounds show a normally developing baby because most babies are born perfectly healthy. However, expectant parents should be aware of why their doctor ordered the ultrasound, what the process entails, what we are looking for and what we could possibly find. Most babies with birth defects – about 90 percent – are born to women with no risk factors (1), so unexpected information is always a possibility.
When a woman undergoes an ultrasound, she very frequently gets scanned by a sonographer. A sonographer’s job is to take pictures of the baby for the doctor, and it’s the doctor’s role to tell you whether the baby looks healthy. The sonographer evaluates the baby from head to toe, assesses the amniotic fluid and the placenta, and most of the time everything looks reassuring. There is always a chance the doctor may find something that could be only mildly concerning, or in some cases more severe.
Soft signs like CPCs are just one example of things we can see on a prenatal ultrasound that slightly increase our concern, but almost always result in the birth of a completely healthy baby. Soft signs are present in as many as 1 in 20 babies. In addition to CPCs, ultrasounds can also detect:
- extra skin behind a baby’s neck (increased nuchal fold)
- extra fluid in the kidneys (pyelectasis)
- a bright spot in the baby’s heart (intracardiac echogenic focus)
- a small or absent bone in the nose (hypoplastic/absent nasal bone)
Babies with any of these findings are extremely likely to be born without health concerns or genetic conditions, especially when there are no other risk factors present in the pregnancy. In addition to soft signs, there are normal variants that may be identified and cause undue anxiety, including differences seen in the placenta or in the amount of amniotic fluid or babies that may measure smaller or bigger than average.
All babies are also evaluated for birth defects, and 2-3 percent of pregnant woman undergoing an ultrasound will learn their baby has one (2). These birth defects can range from having no major effect on the baby’s health, to having some effect and possibly needing treatment, to being very severe.
Undergoing Prenatal Genetic Testing
On a similar note, many pregnant women undergo optional genetic tests, most of which are performed on the mom’s blood. Some parents may have the misconception that a genetic test is performed simply to find out the sex of the baby, and since the blood tests pose no risk to the pregnancy, they don’t hesitate to have them. But these tests can uncover unnerving or surprising things about your baby’s health, so it’s important to ask yourself and your healthcare provider questions before proceeding, including:
- What is this testing?
- Do I want to know the information this test will provide?
- What will I do with this information?
To learn more about common prenatal blood tests, see my interview with the Washington Post.
Pregnancy is already filled with so many feelings – including nausea, fatigue, excitement and anticipation. Prenatal screening can create more feelings – sometimes reassurance, sometimes concern. This blog is not intended to create anxiety or fear, but rather increase your understanding of what you might expect from prenatal screening.
One thing you can count on is, if you do receive unexpected results, a genetic counselor can help you sort through what they mean and how to move forward. If you have any concerns related to your pregnancy or have questions about ultrasounds, genetic testing options or potential risk factors, you can find a genetic counselor at FindaGeneticCounselor.com.
Blair Stevens, MS, CGC, is a National Society of Genetic Counselors Prenatal Expert and a genetic counselor at University of Texas Health Science Center.
- Long G, Sprigg A. A comparative study of routine versus selective fetal anomaly ultrasound scanning. J Med Screen. 1998;5(1):6–10.
- A randomized trial of prenatal ultrasonographic screening: Impact on the detection, management, and outcome of anomalous fetuses James P. Crane, MD: Michael L. LeFevre, MD, MSPH,b Renee C. Winborn, RDMS: Joni K. Evans, MS,c Bernard G. Ewigman, MD, MSPH,b Raymond P. Bain, PhD,c Frederic D. Frigoletto, MD,d Donald McNellis, MD," and the RADIUS Study Group