Diagnostic ultrasound ( PDFDrive )

1148 PART IV Obstetric and Fetal Sonography
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FIG. 33.17 Abnormal Ears. (A) Week 28 fetal sonography showing low-set ears and skin tag (arrows) on two-dimensional (B) and threedimensional
(C) images. (D) A different 27-week fetus with agnathia, microstomia, and low-set, abnormally turned ears.
EAR ABNORMALITIES
Abnormalities of the ears can be very diicult to diagnose on
fetal sonography, but low-set ears are associated with multiple
syndromes, including Noonan syndrome and certain trisomies.
Low-set ears are described as the helix joining the cranium at a
level below a horizontal plane through the inner canthi of the
eyes. Ear anomalies may be more easily detected on 3-D sonography
than on 2-D studies 44,45 (Fig. 33.17).
Microtia, or small ears, is a rare anomaly with an incidence
of approximately 1 per 10,000 live births 46 and is oten associated
with syndromes and aneuploidy. Of 96 aneuploid fetuses, Yeo
and colleagues 47 reported that 66% had small (<10th percentile)
ears on sonography.
Otocephaly is a condition with union of the ears on the front
of the neck and is caused by failure of ascent of the auricles
during embryologic development. his is usually a fatal anomaly,
oten associated with agnathia or micrognathia, as well as
holoprosencephaly. he most severe form of otocephaly may be
associated with absence of the eyes, forebrain, and mouth.
MIDFACE ABNORMALITIES
Hypoplasia
he midface is the area between the upper lip and forehead.
Midface hypoplasia can arise from a variety of causes, including
syndromes such as Apert, Crouzon, Treacher Collins, 48 Wolf-
Hirschhorn, 49 Pfeifer (see Fig. 33.13), Turner, and trisomy 21.
Midface hypoplasia may also result from facial clets, craniosynostosis,
and skeletal dysplasias. Midface hypoplasia is best
demonstrated on sagittal midline views of the face, where one
can see abnormal concavity of the midface, between the lower
margin of the orbits and the upper jaw (Figs. 33.18 and 33.19).