Detection rate of fetal CNS anomalies by first and second trimester ultrasound screening

  • Mahyar Mohammadifard Department of Radiology, Imam Reza Educational Hospital, Birjand University of Medical Sciences, Birjand, Iran.
  • Nasrin Khorashadizadeh Department of Radiology, Valie-asr Hospital, Birjand University of Medical Sciences, Birjand, Iran.
  • Maryam Zarouni Department of Radiology, Birjand University of Medical Sciences, Birjand, Iran.


Objectives: The aim of this study was to detect CNS abnormalities in the first and second trimester by ultrasound.
Methods: This cross-sectional study was performed on pregnant women who referred to the radiology department of Imam Reza and Valiasr hospitals in Tehran-Iran during 2019-2020. After obtaining informed consent, pregnant women were screened in the first trimester at week 13-13 and then in the second trimester at week 18-20 by a 5-8 MHz Ultrasound Transducer. Each ultrasound included examination of the fetal brain and vertebrae at the axial coronal and sagittal planes in the most important anatomical areas, including the trans-thalamic (TT) or the trans-ventricular (TV) plane, transverse cerebellar, and vertebral canal plan. Ultrasound of the first and second trimesters of all mothers was performed. Information of all pregnant mothers was collected and recorded. Data analysis was performed using SPSS software version 25.
Results: In this study, 2234 pregnant women were included in the study. The total rate of detected anomalies was found to be 1.3%. The rate of abnormalities detected in the first trimester was far less than in the second trimester. The prevalence of CNS anomalies in the population under 30 years of age was also found 0.9%, while it was 1.6% in the population over 30 years of age.
Conclusion: Second-trimester ultrasound is the method of choice in diagnosing central nervous system abnormalities. However, first-trimester ultrasound is the diagnostic method for structural abnormalities of the skull.
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How to Cite
MOHAMMADIFARD, Mahyar; KHORASHADIZADEH, Nasrin; ZAROUNI, Maryam. Detection rate of fetal CNS anomalies by first and second trimester ultrasound screening. Journal of Contemporary Medical Sciences, [S.l.], v. 7, n. 3, p. 164-166, june 2021. ISSN 2413-0516. Available at: <>. Date accessed: 21 jan. 2022. doi: