Ultrasound Technology

When I went for my routine ultrasound in April, I fully expected to take home the same fuzzy 2D images as I had in my previous two pregnancies. We’ve all seen those images where the baby looks more like something from one of the “Alien” movies rather than a real baby. Yet, despite that fact, I vividly recall placing the delicate images from both of my previous pregnancies in a photo album and proudly showing off my little black-and-white blobs to everyone. With this pregnancy, however, I was pleasantly surprised by the remarkable clarity and crispness of the 3D/4D images that I brought home.
But I was curious, have these imaging advancements in ultrasounds improved prenatal care?

First Trimester Screening/Integrated Screening
3D/4D imaging certainly provides clearer pictures for parents, but surprisingly, 2D is still the preferred format for routine fetal evaluation. However, the advances in 2D imaging have been significant in the past 5-10 years.
“Ultrasound technology has improved. … [but] improved resolution of 2D ultrasound has made the most difference,” says Dr. Heather Mertz, the medical director of the Comprehensive Fetal Care Center with Wake Forest University Baptist Medical Center in Winston-Salem.

One of the biggest impacts on prenatal care has been the integration of the first-trimester screen. This relatively new technology involves an ultrasound, generally performed between 11 and 13 weeks gestation, to measure nuchal translucency (NT). According to the American College of Obstetricians and Gynecologists (ACOG), “research has shown an association between fetuses with certain chromosomal abnormalities and ultrasonographic findings of an abnormally increased NT [an area at the back of the fetal neck].”

At the same time the ultrasound is performed, a blood screen is drawn to measure pregnancy hormones. The NT measure, hormone levels and maternal age risk factors are combined to determine an overall risk factor for chromosomal abnormalities such as Down Syndrome and Trisomy 18, where a baby has three of the 18th chromosome. It is usually fatal.

The NT measure can also assist in identifying fetal cardiac disorders. The chromosomal abnormality detection rate with the first trimester screen is 85 percent, with a false positive rate of 5 percent.

Many women also opt for integrated screening, which combines the test results from the first trimester screen with blood test results taken from the mother at 15-18 weeks gestation. While pregnant women have to wait longer for results, the integrated screening provides more accurate results. The screening will detect up to 92 percent of babies with Down Syndrome and up to 90 percent of babies with Trisomy 18. Unlike the first trimester screen, the integrated screening will also detect up to 80 percent of babies who have open neural tube defects such as spina bifida.

As a result of the first trimester screen and integrated screening, fewer women are choosing to have more invasive testing such as amniocentesis or chorionic villus sampling (CVS), both of which carry a risk of miscarriage. “We have definitely seen those numbers go down,” says Dr. Mertz.
Dr. Devon Delaney Millard, an OB-Gyn at Northcross OB-Gyn in Huntersville agrees. “With a normal first trimester screen, it has given us the power to reassure patients that everything is OK.”

A recent study performed by Cornell University’s Weill Medical College in New York City also concluded that “higher rates of nuchal translucency screening were associated with lower rates of chorionic villus sampling and invasive testing.”

3D/4D Imaging
While the clarity of 2D imaging has made the biggest impact on prenatal care, 3D/4D imaging gives doctors and sonographers a method for further evaluation. 2D imaging might detect an abnormality, but 3D/4D imaging is used to enhance the finding or allow the patient to see the abnormality for herself.

April Benfield, a diagnostic medical sonographer at the Comprehensive Fetal Care Center explains: “When we find an abnormality with the 2D ultrasound, if the area that we are focusing on is in a good window, then we can use the 3D/4D to evaluate it further. We have used it to look at abnormalities of the abdominal wall, face, spine, limbs, etc. For example, if we see a cleft lip in the 2D, then we can look at the face in a 3D/4D image and sometimes get a better idea of what it looks like. It can also help the patient to see exactly what we are seeing. Right now, we still use 2D primarily when evaluating a fetus, [but] … 3D/4D gives us a volume of information that we can save and manipulate once the examination has been completed.”

Gynecology has also benefited from this technology as 3D/4D imaging is now being used to study structural problems of the uterus and diagnose ovarian tumors, endometrial polyps and fibroids.

3D/4D imaging has also had a significant impact on assessing fetal cardiac abnormalities as it allows doctors to see the heart from different angles and assess blood flow. The improved resolution also allows doctors to better analyze data, giving parents the information they need to prepare for their child’s birth and plan accordingly.

These advances in technology will likely continue in obstetrics and gynecology as the technology is constantly changing and improving, and the result is better patient care.

Myra Wright, editor of Piedmont Parent, a sister publication of Charlotte Parent, is due in September.