Prediction of fetal sex in the first quarter ultrasound screening: ecuadorian experience
Keywords:
DIAGNÓSTICO PRENATAL; EMBARAZO; PRIMER TRIMESTRE DEL EMBARAZO; ULTRASONOGRAFÍA PRENATAL., PRENATAL DIAGNOSIS; PREGNANCY; PREGNANCY TRIMESTER, FIRST; ULTRASONOGRAPHY, PRENATAL., DIAGNÓSTICO PRÉ-NATAL; GRAVIDEZ, PRIMEIRO; TRIMESTRE DA GRAVIDEZ; ULTRASSONOGRAFIA PRÉ-NATAL.Abstract
Introduction: early prediction of fetal sex constitutes a relevant support in first-trimester screening, especially in contexts where genetic testing is not accessible and ultrasound represents the main diagnostic resource available.
Objective: to determine the accuracy of first-trimester ultrasound in predicting fetal sex through sagittal evaluation of the genital tubercle and its anatomical orientation.
Methods: descriptive, multicenter, prospective longitudinal study conducted on an intentional sample of 105 pregnant women attended at two specialized centers between 2021 and 2023. Ultrasound sex determination was based on the angle of the genital tubercle relative to the lumbosacral line, compared with confirmatory results from the second trimester or at birth. Descriptive and inferential statistical methods were employed.
Results: initially, 52,4 % of fetuses were estimated to be female. Male prediction reached an accuracy of 94 %, while female prediction obtained 83,6 %. The overall effectiveness of the protocol was 88,5 %, with statistically significant associations between the initial assignment and the definitive sex.
Conclusions: the orientation of the genital tubercle is a reliable predictor of fetal sex during the first trimester, demonstrating high accuracy in this Latin American population. These findings support the usefulness of the ultrasound approach as an accessible alternative in clinical contexts where early genetic testing is not available.
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