Pelvic CT Morphometry in Down Syndrome: Implications for Prenatal US Evaluation—Preliminary Results

Abstract

Patients with Down syndrome had a larger mean iliac angle and a shorter mean iliac length. The most pronounced differences were at the middle sacral level, which suggests that this may be the optimal level for measuring these parameters at prenatal US.

The iliac angle: a sonographic marker of trisomy 21 during the midtrimester: dependency of fetal lying?

“…This sign is present in 80% of patients with trisomy 21. A recent study using CT in fixed dead fetuses has shown that iliac wings are shorter, diverge more, and are oriented more frontally [12]. Our study agrees with the obstetrical studies that have shown that the anomalies of the pelvic bones can already be quantified in utero by measuring the iliac wing angle of the fetus [13,14,17,18,19,20,21].…”

“…Caffey and Ross [4] described, in 1956, the morphological anomalies occurring on the pelvic bones of trisomy 21 patients: widening and splaying of the iliac wings, flattening of the acetabular roof, and increased iliac dorsal curvature [4,5,6,7,8,9,10,11,12]. This sign is present in 80% of patients with trisomy 21.…”

“…This angle must be measured on a transverse view of the fetal pelvis. The measurement must be obtained in a symmetric transverse view of the fetal pelvis, and must include the more cephalic part of the iliac wings, where the angle is wider [12,17].…”

“…The pelvic bone in an antero-posterior abdominal X-ray of Down's syndrome infant has a typical appearance, distinct from that of a normal child [4]. The wings of the ilium are wide, flared, and flattened due to an increased angle between them [4,5,6,7,8,9,10,11,12]. This anomaly already exists in utero and several teams have measured the iliac wing angle in utero to assess the importance of the anomaly.…”

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

“…Radiological (roentgenology) examinations of neonates with Down syndrome showed that the iliac wing angle in these patients is wider than that in healthy neonates (Kaufmann et al , 1961; Mortensson and Hall, 1972; Andren et al , 1968). A recent study using computed tomography in fixed dead fetuses has shown that the iliac wings are shorter, diverge more, and are oriented more frontally (Freed et al , 2000). Also, current ultrasonographic studies showed that fetuses with trisomy 21 also appear to have a wider iliac angle than do normal fetuses (Bork et al , 1997; Shipp et al , 1997; Grangé et al , 2000; Belics et al , 2003; Lee et al , 2010).…”