The value of detailed first-trimester ultrasound in the era of noninvasive prenatal testing

BACKGROUND: In 2020, the American College of Obstetricians and Gynecologists recommended noninvasive prenatal testing be offered to all patients. However, current societal guidelines in the United States do not universally recommend a detailed first-trimester ultrasound.OBJECTIVE: This study aimed to determine the additional findings identified through first-trimester ultrasound that would have otherwise been missed if noninvasive prenatal testing was used alone as a first trimester screening method.STUDY DESIGN: This was a retrospective cohort study involving 2158 pregnant patients and 2216 fetuses that were seen at a single medical center between January 1, 2020, and December 31, 2022. All those included underwent both noninvasive prenatal testing and detailed first trimester ultrasound between 11.0 and 13.6 weeks of gestation. Noninvasive prenatal testing results were categorized as low risk or high risk, and first-trimester ultrasound results were categorized as normal or abnormal. Abnormal first-trimester ultrasounds were further classified as first-trimester screening markers (increased nuchal translucency, absent nasal bone, tricuspid regurgitation, and ductus venosus reverse a-wave) or structural defects (the cranium, neck, heart, thorax, abdominal wall, stomach, kidneys, bladder, spine, and extremities). Descriptive statistics were used to report our findings.RESULTS: Of 2216 fetuses, 65 (3.0%) had a high-risk noninvasive prenatal testing result, whereas 2151 (97.0%) had a low-risk noninvasive prenatal testing result. Of those with a low-risk noninvasive prenatal testing result, 2035 (94.6%) had a normal first-trimester ultrasound, whereas 116 (5.4%) had at least 1 abnormal finding on first trimester ultrasound. The most common screening marker detected within the low-risk noninvasive prenatal testing group was absent nasal bone (52/2151 [2.4%]), followed by reversed a-wave of the ductus venosus (30/2151 [1.4%]). The most common structural defect in this group was cardiac abnormality (15/2151 [0.7%]). Overall, 181 fetuses were identified as having "abnormal screening" through either a high risk noninvasive prenatal testing result (n=65) or through a low-risk noninvasive prenatal testing result but abnormal first-trimester ultrasound (n=116). In summary, the incorporation of first-trimester ultrasound screening identified 116 additional fetuses (5.4%) that required further follow-up and surveillance than noninvasive prenatal testing alone would have identified.CONCLUSION: Detailed first-trimester ultrasound identified more fetuses with a potential abnormality than noninvasive prenatal testing alone. Therefore, first-trimester ultrasound remains a valuable screening method that should be used in combination with noninvasive prenatal testing.