Visualization of the Fetal Corpus Callosum in Routine Second Trimester Screening Ultrasound Examinations.

Area of Science:

• Medical Imaging
• Fetal Ultrasound
• Neurosonography

Background:

• Corpus callosum (CC) visualization is crucial for fetal neurodevelopmental assessment.
• Optimizing ultrasound techniques can improve diagnostic accuracy in prenatal screenings.

Purpose of the Study:

• To determine the visualization rate of the corpus callosum (CC) in the mid-sagittal plane during second-trimester ultrasound (18-22 weeks' gestation).
• To compare current CC visualization rates with those from 5 years prior.
• To identify factors influencing CC visualization, including fetal head position, gestational age, maternal BMI, and the need for transvaginal ultrasound.

Main Methods:

• Retrospective analysis of 999 second-trimester screening ultrasound examinations (January-June 2019).
• Scoring system (0-4) for CC visualization completeness.
• Chi-squared test for comparing visualization rates over time.
• Analysis of fetal head position, gestational age, maternal BMI, and transvaginal ultrasound use.

Main Results:

• Complete CC visualization improved significantly to 92.1% from a previous rate of 71.3% (P < .001).
• Transvaginal ultrasound was needed in 4.4% of cases.
• Craniocaudal fetal head position yielded the highest success rate (98.2%).
• Nonvisualization was higher before 20 weeks' gestation (7.4% vs. 3.0%, OR=2.63, P=.012).
• Higher maternal BMI (≥30.0 kg/m²) correlated with increased nonvisualization.

Conclusions:

• Complete mid-sagittal CC visualization is achievable in routine second-trimester morphology ultrasound.
• Standardized protocols and training significantly improve fetal imaging quality.
• Optimized techniques enhance the detection of fetal brain anomalies.