Prenatal ultrasonographic measurement of the fetal iliac angle during the first and second trimester of pregnancy

Abstract

Objectives: The aim of this study was to present our results of the sonographic measurement of the fetal iliac angle during the first and second trimesters of pregnancy.

Methods: A total of 2168 fetal iliac angle measurements were performed in a transverse section of the fetal pelvis. The iliac angle measurements were compared in fetuses with trisomy 21 (n = 52) and fetuses with normal karyotype (n = 1980). The sensitivity, specificity, positive predictive value, negative predictive value and false positive rate in trisomy 21 fetuses were compared for multiple cut-off value. Statistical significance for measurements was estimated for trisomy 21.

Results: A total of 2064 fetuses had adequate images for satisfactory measurement of the iliac wing angle and 1831 patients asked for a genetic invasive procedure. Of the fetuses with chromosomal aberrations, only the fetuses with trisomy 21 were included in the investigation. The risk of trisomy 21 in our population was 1 of 39. In the euploid fetuses, the mean iliac wing angle was 63.72°. The mean iliac wing angle in the fetuses with trisomy 21 was 90.32°, significantly higher than those seen in fetuses with normal karyotype.

Conclusion: The proven larger iliac wing angle in neonates with Down syndrome can be demonstrated sonographically during the pregnancy, especially in the first and second trimesters. This marker may be useful in prenatal screening or exclusion of trisomy 21.