Accuracy of fetal gender determination in the first trimester using three-dimensional ultrasound.
OBJECTIVE
To evaluate the accuracy of three-dimensional (3D) ultrasound in fetal gender assignment in the first trimester.


METHODS
A series of pregnant women attending at 11 to 13 + 6 weeks for the nuchal translucency (NT) scan were enrolled into the study. An ultrasound volume of each fetus was obtained and stored for offline analysis. On the reconstructed mid-sagittal plane, the angle between the genital tubercle and an imaginary line passing tangentially through the fetal back (genital angle) was estimated and a receiver-operating characteristics (ROC) curve was constructed to determine the best cut-off for genital angle in fetal male gender determination. Fetal gender was subsequently ascertained in all cases. To calculate the interobserver variability, a second operator repeated the measurements.


RESULTS
There were 85 cases included in the study. The genital angle in males was significantly higher than that in females (51.2 ± 11.3° (n = 36) vs. 18.9 ± 4.1 (n = 49), P < 0.001). The ROC curve revealed the estimated genital angle to have a high degree of accuracy in fetal gender determination (area under the curve ± SE = 1.000 ± 0.001). The best cut-off for male gender determination was found to be between 27° and 29° (sensitivity, 100%; specificity, 98.0%). There was a high degree of correlation between the two operators (r(2) = 0.998; coefficient of variation = 5.4%).


CONCLUSIONS
3D ultrasound is a highly accurate and reproducible tool for fetal gender assignment prior to 14 weeks of gestation.
Youssef
A
A
Department of Obstetrics and Gynecology, University of Bologna, Bologna, Italy.
Arcangeli
T
T
Radico
D
D
Contro
E
E
Guasina
F
F
Bellussi
F
F
Maroni
E
E
Morselli-Labate
A M
AM
Farina
A
A
Pilu
G
G
Pelusi
G
G
Ghi
T
T
D000328:Adult; D019540:Area Under Curve; D005260:Female; D005836:Genitalia, Female / Q000000981:diagnostic imaging* / Q000196:embryology; D005837:Genitalia, Male / Q000000981:diagnostic imaging* / Q000196:embryology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012372:ROC Curve; D015203:Reproducibility of Results; D012732:Sex Determination Analysis / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult