Background
First-trimester ultrasound scans were introduced to China for nearly 20 years. The
ability of first-trimester ultrasound screening to detect different malformations
was variable. A recent systematic review concluded that the use of a standardized
anatomic protocol was the most crucial factor to improve the sensitivity of first-trimester
ultrasound screening for anomalies. Standardized sectional scans have long been used
for routine anatomy screening during the second trimester. However, during the first
trimester, most of the previous studies have described the observation of anatomic
structures but have not specified clearly the standard sectional views.
Objective
We aimed to determine the performance of routine first-trimester scans using a standardized
anatomic protocol for detecting structural abnormalities in China.
Study Design
This was a large retrospective study involving 59,063 sequential unselected pregnancies.
Scans at 11 to 13+6 weeks were performed in a single center during a 7-year span. All fetuses were examined
following a predefined protocol for standardized views.
Results
From October 2008 to December 2015, first-trimester scans were performed in 53,349
pregnant women with available outcome. Of these, there were 1578 (3%) pregnancies
that presented with at least 1 fetal structural abnormality. The detection rate for
first-trimester screening was 43.1% (95% confidence interval, 40.6%–45.5%). Routine
first-trimester scans detected 95.6% of abdominal wall defects, 66.3% of nervous system
defects, 33.8% of limbs and skeleton malformations, 30.8% of facial abnormalities,
21.2% of urogenital abnormalities, 18.4% of thoracic and lung abnormalities, and 4.1%
of gastrointestinal tract abnormalities. During the first trimester, 37.7% of cardiac
defects were identified and included 57.9% of major cardiac defects and 2.6% of mild
cardiac defects. A robust high detection rate for anencephaly, exencephaly, cephalocele,
holoprosencephaly, exomphalos, gastroschisis, Pentalogy of Cantrell, sirenomelia,
and body stalk anomaly was achieved during routine first-trimester scans.
Conclusion
A standardized anatomic protocol is advised when performing routine first-trimester
ultrasound screening. It is recommended that screening for severe structural abnormalities
should be extended to the first trimester.
Key words
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Article Info
Publication History
Published online: October 27, 2020
Accepted:
October 22,
2020
Received in revised form:
September 30,
2020
Received:
July 14,
2020
Footnotes
The authors report no conflict of interest.
This research was supported by the National Key Research and Development Program and the National Nature Science Foundation of China, and the Shenzhen Science and Technology project.
Cite this article as: Liao Y, Wen H, Ouyang S, et al. Routine first-trimester ultrasound screening using a standardized anatomic protocol. Am J Obstet Gynecol 2021;224:396.e1-15.
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