ABSTRACT

Lubusky, M., Studnickova, M., Jaburek, L., Prochazka, M. Fetal gender assignment by first trimester ultrasound Objective. The aim of the work was to assess the feasibility and accuracy of fetal gender assignment by transabdominal ultrasound in the first trimester of pregnancy. Ultrasound examination aimed at determining fetal gender was performed in the first trimester of pregnancy at 12–14 weeks (CRL, 45–82.4 mm). A total of 1222 fetuses were examined, all were from a single pregnancy without established morphological and chromosomal abnormalities in the fetus or newborn. Methods. Ultrasound examination was performed transabdominally and in all fetuses the crown-rump length (CRL) was measured. The genital area of the fetus was examined in the mid-sagittal plane, in the neutral position of the fetus. The angle between the genital tubercle axis and a horizontal line through the lumbosacral skin surface was measured. Angles >30° established the gender to be male, if the axis of the genital tubercle ran parallel (< 10°) or convergent to the horizontal line, gender was established as female, if the angle was intermediate (10–30°) gender was not determined. The result of ultrasound examination was compared to the phenotypic sex of the newborn after delivery. Results.It was possible to establish gender in 1025 of atotal of 1222 fetuses (84%). In 197 fetuses (16%) it was not possible to determine gender during ultrasound examination (an intermediate angle 10–30°, unfavorable fetal position or maternal Určení pohlaví plodu při ultrazvukovém vyšetření v I. trimestru těhotenství 1, 2doc. MUDr. Marek Ľubušký, Ph.D., 1 MUDr. Martina Studničková, 1 MUDr. Ladislav Jabůrek, 1 doc. MUDr. Martin Procházka, Ph.D. 1 Univerzita Palackého v Olomouci, Lékařská fakulta a Fakultní nemocnice Olomouc, Porodnicko-gynekologická klinika 2 Univerzita Palackého v Olomouci, Lékařská fakulta a Fakultní nemocnice Olomouc, Ústav lékařské genetiky a fetální medicínygynekologie a porodnictví 910 Postgraduální medicína 2012, 14, č. 8 www.postgradmed.cz habitus). In 51 of 1025 fetuses (5%) it was not possible to perform a comparison of gender assignment at ultrasound examination with phenotypic sex of the newborn after delivery. In the remaining 974 fetuses, gender was correctly established in 92.5% of cases (901/974), male gender in96.3% (471/489), female gender in 88.7% (430/485). Feasibility as well as accuracy in determining gender during ultrasound examination increased with growing fetal CRL. At CRL < 50 mm (gestational age < 11+4) feasibility was 39.1% and accuracy 30.5% (40.9% in male gender vs 24.3% in female gender). At CRL 50–54.9 mm (gestational age 11+4 to 12+0) feasibility was 63.5% and accuracy 75.0% (89.1% in male gender vs 66.7% in female gender). At CRL 55–59.9 mm (gestational age 12+0 to 12+2) feasibility was 90.5% and accuracy 96.6% (99.1% in male gender vs 93.5% in female gender). At CRL ≥ 60 mm (gestational age ≥ 12+2) feasibility was 97.4% and accuracy 100.0% (100.0% in male gender vs 100.0% in female gender). The difference between male and female gender was not statistically significant. Conclusion. Fetal gender may reliably be determined by transabdominal ultrasound when CRL ≥ 60 mm (gestational age ≥ 12+2). Male gender may already be reliably determined when CRL ≥ 55 mm (gestational age ≥ 12+0). If CRL < 50 mm (gestational age < 11 + 4) gender cannot be reliably predicted. It is always necessary to take into account the maternal habitus, the position of the fetus and the imaging possibilities of the ultrasound device. Experience and erudition of the examiner are very important.