Diagnostic ultrasound ( PDFDrive )

CHAPTER 33 The Fetal Face and Neck 1135
A B C
T
D E F
FIG. 33.2 Normal Fetal Face. (A) Three-dimensional (3-D) sonogram of a normal 30-week fetus. (B) Nose and lips. Coronal sonogram of
normal nostrils and maxillary teeth of a different fetus at 33 weeks’ gestation. (C) Proile of the face of a 17-week fetus shows a normal nasal
bone (long arrow), maxilla (arrowhead), and mandible (short arrow). (D) Normal orbits in axial view (cursors: +, outer orbital distance; x, inner orbital
distance). (E) Normal maxilla. Axial view of anterior aspect of the maxilla in a 17-week fetus shows the tongue (T) and tooth buds in the alveolus
(arrows). (F) Sagittal T2-weighted magnetic resonance image of a normal fetal face at 27 weeks’ gestation shows normal midline structures, such
as corpus callosum (short arrow), cerebellar vermis (long arrow), and secondary palate (arrowhead).
image can then be rotated to show the upper lip and palate
clearly. Coronal (see Fig. 33.2B) and axial views of the fetal nose
and lips are obligatory in screening for fetal clet lip.
he sagittal facial proile view is acquired whenever possible
and should demonstrate the presence and normal coniguration
of the nasal bone, lips, chin, and forehead (see Fig. 33.2C).
hree-dimensional volumes 10-13 can frequently be obtained and
can be helpful for characterizing abnormalities. Axial views of
the orbits can be obtained to verify that both globes are present,
of normal size, and at a normal distance apart (see Fig. 33.2D).
Axial images of the maxilla and alveolar ridge can be obtained
to determine if a clet primary palate is present (see Fig. 33.2E).
he palate separates the nasal cavity from the oral cavity. he
secondary palate is diicult to visualize on 2-D sonography but
may be evaluated with special 3-D sonographic views 14-16 and is
oten readily visible on midline sagittal and coronal fetal magnetic
resonance imaging (MRI; see Fig. 33.2F).
Images of the fetal neck are obtained in sagittal, axial, and
coronal planes to evaluate the cervical spine and airway and to
assess for masses (Fig. 33.3). he neck should also be evaluated
for abnormal positioning, such as hyperextension, which can be
present with anterior neck masses such as an enlarged thyroid
or cervical teratoma. hickening of the nuchal fold is evaluated
at the second-trimester survey and is measured in the suboccipital
bregmatic plane, where notable landmarks include the cavum
septum pellucidum, cerebral peduncles, cerebellar hemispheres,
and cisterna magna.
ABNORMALITIES OF THE HEAD
Abnormal Size
he fetal head is typically oval in coniguration, and in this case,
measurements of biparietal diameter (BPD) and head circumference
will give similar estimates of gestational age. If sonographic
head measurements are three standard deviations (SDs) below
the mean, microcephaly is diagnosed. 17 If the measurements are
greater than 3 SDs above the mean, macrocephaly is suggested. 5
Abnormalities of head size are important. Microcephaly may
be associated with abnormalities of brain development and oten
leads to poor neurologic outcome. Macrocephaly may have a
benign cause, such as a family history of a large head, or pathologic