Sonographic measurement of the fetal iliac angle cannot be used alone as a marker for trisomy 21.
The fetal iliac wings angle was studied in 255 fetuses before amniocentesis at 16.7 weeks (+/- 1.3), using a sonographic axial view of the fetal pelvis. The measurement could be performed in 208 fetuses (81.6%), of whom 4 had trisomy 21 (T 21). The mean iliac angle was greater in fetuses with T 21 than in normal fetuses (69.8 degrees vs. 88.7 degrees; p = 0.03). This measurement is subject to significant intra- and interexaminer variability (interclass correlation coefficient: 0.65 and 0.23, respectively). When a 90 degrees value is used as a threshold, specificity, sensitivity, positive and negative predictive values are, respectively, 80, 75, 7. 0 and 99.4%. The 20% rate of false-positives rules out the use of this measurement as the sole criterion for the indication of amniocentesis for T 21 antenatal diagnosis.
Grangé
G
G
Maternité Port-Royal, Hôpital Cochin, Paris, France. gilles.grange@cch.ap-hop-paris.fr
Thoury
A
A
Dupont
J
J
Pannier
E
E
LeRhun
F
F
Goussot Souchet
M
M
Goffinet
F
F
Cabrol
D
D
D004314:Down Syndrome / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging* / Q000473:pathology; D011237:Predictive Value of Tests; D011247:Pregnancy; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal