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Chapter 33 ■ The Fetal Face and Neck 1167
A B
FIGURE 33-1. Embryology of the face. Stages of development of the fetal face. Note the initial wide separation of the eyes, high
wide separation of the nostrils (nasal placodes), and low position of the ears. (From Moore KL: Essentials of human embryology. Toronto,
1988, BC Decker.)
prominences fuse, and the maxillary prominences begin
to form the upper jaw. The nasal septum forms as the
medial nasal prominences join in the midline. The edges
of the optic fissures fuse, and the hyaloid vessels are
present in the center of the optic stalk. These vessels will
eventually form the retinal artery and vein.
By the seventh week, the tip of the nose is visible in
profile, and the pinna of the ears is taking shape. The
central axis of the nose and philtrum are formed as fusion
of the medial nasal prominences is completed. Eyelids
become prominent.
developing eye is up to 2 mm in diameter.
2-5
By the end of the eighth week, the
6
Neck
Development of the fetal neck is similarly complex,
with extensive embryologic events contributing to development of vascular, neurologic, musculoskeletal, lymphatic, and endocrine systems. The laryngotracheal
groove forms during the fourth week of gestation along
the floor of the primitive mouth. After evagination of
this groove, the laryngotracheal diverticulum forms. The
distal end forms the lung bud. The endoderm of this
diverticulum forms the epithelium of the larynx and
trachea. The endothelium of the larynx proliferates and
temporarily occludes its lumen. Recanalization occurs
by the tenth gestational week, with formation of the
laryngeal ventricle, vocal folds, and vestibular folds. The
fourth and sixth pharyngeal arches form the surrounding
cartilage and muscles.
2-4
At 4 to 6 weeks’ gestation, right and left jugular lymph
sacs develop as diverticula of the subclavian veins. Lymphatic capillaries permeate the body and drain into these
sacs. Abnormal connections between the lymphatic sacs
and venous system are thought to contribute to lymphatic malformation and thickened nuchal translucency
in the first trimester, as well as thickened nuchal fold in
the second trimester.
7
of Ultrasound in Medicine 2007 practice guidelines,
only visualization of the fetal upper lip is mandatory
during an anatomic survey.
1
Although not required, it is
possible to obtain exquisite multiplanar two-, three-, and
four-dimensional (2-D, 3-D, 4-D) views of the fetal face
with state-of-the-art equipment.
8
Profile and 3-D9 views
are helpful, especially when a true coronal view cannot
be obtained because of fetal position. Sagittal 3-D
volumes of the fetal face can often be obtained in these
situations, and the image can then be rotated to show
the upper lip and palate clearly. Coronal and axial views
of the fetal nose and lips are obligatory in screening for
fetal cleft lip (Fig. 33-2, A and B).
The sagittal facial profile view is acquired whenever
possible and should demonstrate the presence and
normal configuration of the nasal bone, lips, chin, and
forehead. Axial views of the orbits can be obtained to
verify that both globes are present, of normal size, and
at a normal distance apart (Fig. 33-2, C). Axial images
of the maxilla and alveolar ridge can be obtained to
determine if a cleft primary palate is present (Fig. 33-2,
D). The palate separates the nasal cavity from the oral
cavity. The secondary palate is difficult to visualize on
2-D sonography but may be evaluated with special 3-D
sonographic views
10-12
and is often readily visible on
midline sagittal and coronal fetal magnetic resonance
imaging (MRI; Fig. 33-2, H ).
Images of the fetal neck are obtained in sagittal, axial,
and coronal planes to evaluate the cervical spine, airway,
and to assess for masses (Fig. 33-3). The 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.
Thickening of the nuchal fold should be 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.
SONOGRAPHY OF THE NORMAL
FETAL FACE
Sonographic evaluation of the fetal face is part of the
routine anatomic survey in midpregnancy, but little is
actually required. According to the American Institute
ABNORMALITIES OF THE HEAD
Abnormal Size
The fetal head is typically oval in configuration, and in
this case, measurements of biparietal diameter (BPD)
1168 PART IV ■ Obstetric Sonography
A
T
D
B C
E F
HG
FIGURE 33-2. Normal fetal face. A, Nose and lips. Coronal sonogram at 36 weeks’ gestation. B, Profile of the face of a 17-week
fetus shows a normal nasal bone (long arrow), maxilla (short arrow), and mandible (arrowhead). C, Normal orbits in axial view (cursors:
+, outer orbital distance; x, inner orbital distance). D, Normal maxilla. Axial view of anterior aspect of the maxilla in a 17-week fetus
shows tooth buds in the alveolus (arrows) and tongue (T). E, Normal mandible. Axial view shows multiple tooth buds. F, 3-D sonogram
of a normal 23-week fetus. G, 3-D sonogram of a normal 30-week fetus in F. H, Sagittal T2-weighted MR image of a normal fetal face
at 27 weeks’ gestation shows normal midline structures, such as corpus callosum (thick arrow), cerebellar vermis (V), and secondary palate
(thin arrow).
and head circumference will give similar estimates of
gestational age. If sonographic head measurements are
three standard deviations (3 SD) below the mean, microcephaly is diagnosed.
13
If the measurements are greater
space-occupying lesion. If the fetal head is sufficiently
large, cephalopelvic disproportion can occur at delivery,
leading to failure of labor to progress and the need for
cesarean delivery.
than 2 SD above the mean, macrocephaly is suggested.5
Abnormalities of head size are important. Microcephaly
may be associated with abnormalities of brain development and often leads to poor neurologic outcome. Mac-
rocephaly may have a benign cause, such as a family
history of a large head, or pathologic causes such as
underlying brain maldevelopment or injury or rarely, a
Abnormal Shape
Abnormal head shape takes many forms. An abnormally
long and narrow (oblong) cranium is described as doli-
chocephaly and is more frequently seen in fetuses in
breech position and in the setting of oligohydramnios.
Chapter 33 ■ The Fetal Face and Neck 1169
A B
FIGURE 33-3. Normal neck. A, Sagittal view. Cervical spine and the soft tissues of the posterior neck can be evaluated along with
the degree of flexion or extension of the neck. B, Axial view shows thyroid (arrows). The carotids medially and the jugular veins laterally
can be seen (open arrows) posterior to the thyroid. The trachea (T) is seen in the midline behind the isthmus and behind it a vertebral
body with a small central developing ossification center (O). The spinal cord (C) is cradled within the vertebral arch.
An abnormally round head is termed brachycephaly,
which may be caused by premature fusion of the coronal
sutures. A lemon-shaped skull, with indentation of the
frontal bones, is often seen in association with open
neural tube defects and the Chiari II malformation
of the hindbrain, but it may also be seen in normal
14,15
fetuses
(Fig. 33-4). A strawberry-shaped skull, presenting as flattening of the occiput and narrowing of the
bifrontal portion of the cranium, may be seen in association with trisomy 18.
16
A cloverleaf-shaped skull is seen
with some dwarfs, especially thanatophoric dysplasia,
and in some fetuses with craniosynostosis.
Craniosynostosis
Craniosynostosis describes a heterogeneous group of disorders in which there is premature fusion of one or
several of the cranial sutures. Although abnormal head
shape may be diagnosed in utero, this diagnosis often
does not become evident until after birth. It occurs in
about 1 in 2500 births. Recent research suggests the
pathophysiology of craniosynostosis is related to abnormal molecular signaling by fibroblast growth factors
(FGFs),
17-19
leading to premature closure of cranial
sutures (Fig. 33-5). About 85% of cases are isolated and
about 15% syndromic. Craniosynostosis is associated
with multiple syndromes, including Apert, Crouzon,
Pfeiffer, Antley-Bixler, Beare-Stevenson, Fetter, and
Carpenter, as well as thanatophoric dysplasia. The
abnormal head shapes resulting from craniosynostosis
can lead to facial abnormalities, including hypertelorism,
hypotelorism, exorbitism, and midface hypoplasia.
Dolichocephaly (oblong head) is the most common
craniosynostosis condition and results from premature
fusion of the sagittal suture. Asymmetrical heads are
termed plagiocephalic.
20
When fetal position is favorable, it is possible to trace
the sutures sonographically and to evaluate their patency
using high-frequency linear array probes.
CLASSIFICATION OF SKULL
DEFORMITIES BASED ON
SUTURES INVOLVED
Dolichocephaly/scaphocephaly: sagittal suture;
most common synostosis
Anterior plagiocephaly: 1 coronal suture
Posterior plagiocephaly: 1 lambdoid suture
Brachycephaly: bilateral coronal suture; second
most common synostosis
Trigonocephaly: metopic suture
Oxycephaly/turricephaly: all skull sutures and
sutures at base of skull
Cloverleaf (kleeblattschädel): all but squamous
(squamosal) suture
Prenatal diagnosis can be difficult; fetuses can appear
normal in midtrimester but show changes in late pregnancy, when normal physiologic molding can be a
confounder. In at-risk cases, head shape changes have
been seen as early as 12 weeks. The fused sutures can
be detected as absence of the sonolucent space normally seen between skull bones. The loss of hypoechoic
suture appearance lags shape changes by 4 to 16 weeks.
1170 PART IV ■ Obstetric Sonography
Ant
Occ
A
A P
C
B
D
E
FIGURE 33-4. Variety of abnormal head shapes. A, Lemon-shaped skull in association with neural tube defect. Axial
sonograms shows concave deformity of the frontal bone (straight arrows) as well as ventriculomegaly (curved arrows) at 22 weeks’ gestation.
B, Brachycephaly and strawberry shape (pointing anteriorly, flat occiput) at 20 weeks in a fetus with trisomy 18. Cephalic index is 96%
(normal, 80%); Occ, occiput; Ant, forehead. C, Craniosynostosis with cloverleaf skull. Note the trilobite shape seen with craniosynostosis
of the coronal (arrowheads) and other sutures except the squamosal in this fetus with thanatophoric dysplasia; A, anterior; P, posterior.
D, Metopic craniosynostosis. Axial sonogram of a 27-week fetus with a pointed anterior skull secondary to metopic synostosis. E, Frontal
bossing in a fetus with hypochondroplasia. Also note a “saddle nose,” with the nasal bone meeting the frontal bone at an abnormal 90
degrees. There is a small thorax and a protuberant abdomen. (A, B, and C courtesy Ants Toi, MD).
Chapter 33 ■ The Fetal Face and Neck 1171
A
C
Three-dimensional multiplanar and surface rendering
are helpful. Associated anomalies can allow differentiation between types.
21-23
Additional problems can arise from the cranial deformity, including intracranial hypertension, obstructive
apnea, proptosis, visual loss, dental malocclusion, and
intellectual impairment. Learning disorders have been
observed in 47% of school-age children.
22
Fetuses prenatally suspected to have craniosynostosis
should undergo detailed neurologic and anatomic sonography. MRI may be helpful. Postnatally, computed
tomography (CT) surface rendering helps confirm the
diagnosis and is needed for surgical treatment planning.
Family history and molecular analysis for FGFR and
B
FIGURE 33-5. Craniosynostoses with cloverleaf skull
deformity. A, Coronal sonogram shows cloverleaf skull deformity
at 37 weeks’ gestation secondary to combined coronal, lambdoidal,
and squamous (squamosal) suture synostosis. B and C, Sagittal and
axial MR images show turribrachycephaly (multiple suture closures
allow only growth superiorly; “tower head”).
TWIST mutations can help. Multidisciplinary counseling, including craniofacial and neurosurgical specialists,
is important because therapy can involve molding
helmets and surgery.
22,24,25
Wormian Bones
Wormian bones are ossicles located in the sutures
or fontanelles and may be associated with multiple
conditions, such as pyknodysostosis, osteogenesis
imperfecta, cleidocranial dysplasia, hypothyroidism,
and trisomy 21.
Three-dimensional views are particularly useful in the assessment of wormian bones
(Fig. 33-6).
1172 PART IV ■ Obstetric Sonography
FIGURE 33-6. Wormian bone. An extra ossification center
(arrow) is identified between the frontal bones of a fetus with
trisomy 18.
DIFFERENTIAL DIAGNOSIS OF
WORMIAN BONES
DIFFERENTIAL DIAGNOSIS OF
FRONTAL BOSSING
Achondroplasia
Acromegaly
Basal cell nevus
Cleidocranial dysostosis
Congenital syphilis
Crouzon syndrome
Fetal trimethadione
Pfeiffer syndrome
Russell-Silver syndrome
Thanatophoric dysplasia
Encephaloceles
An encephalocele or cephalocele is an abnormal protrusion of the brain and/or meninges through a defect in
the skull and is considered a form of spinal dysraphism.
In the United States and Western Europe, the occiput
is the most common location for encephaloceles. Frontoethmoidal encephaloceles are more often found in
Southeast Asia. Many encephaloceles are diagnosed at
fetal sonography, where they present as abnormal defects
in the calvarium with herniation of brain tissue or
meninges. Fetal MRI is excellent for evaluating contents
of the encephalocele and in assessing the appearance of
the intracranial brain parenchyma. Frontal encephaloceles can present during sonographic evaluation of the
fetal face and are often associated with hypertelorism and
midline facial clefting
26
(see Chapter 34).
Cleidocranial dysplasia
Congenital hypothyroidism
Hypophosphatasia
Osteogenesis imperfecta
Trisomy 21
Menkes’ kinky-hair syndrome
Progeria
Pyknodysostosis
Forehead Abnormalities
The forehead is best evaluated in the sagittal profile view,
where the angle between the frontal and nasal bone can
be assessed. Frontal bossing is abnormal prominence of
the frontal bones and is a rare finding on fetal sonography. However, it has been reported in a variety of bony
dysplasias and syndromes, including achondroplasia and
thanatophoric dysplasia, and in syndromes with associated craniosynostosis.
Wolf-Hirschhorn (4p−) syndrome has an abnor-
mally sloped forehead, the “Greek warrior facies” (Fig.
33-7). The forehead can also be sloped in the settings of
microcephaly and encephalocele, in which the forebrain is underdeveloped (Fig. 33-8).
ORBIT ABNORMALITIES
Sonographic evaluation of the fetal orbits is best obtained
in axial or coronal views, where one can confirm the
presence of both orbits, evaluating their sizes, shapes,
and the distance between them. The sagittal view may
help to evaluate abnormal anterior displacement of the
globes (proptosis or exorbitism). The orbits should be
symmetrical in size and the outer and inner interorbital
distances within a normal range. Detailed nomograms
are available for reference
Hypotelorism
Hypotelorism is defined as an abnormally small distance
between the orbits and is often associated with other
anomalies
29,30
(Fig. 33-9). In particular, alobar holo-
prosencephaly can be associated with cyclopia (single
midline eye with failed development of nose with or
without a proboscis; Fig. 33-10), ethmocephaly (hypotelorism with failed development of nose and a proboscis), or cebocephaly (hypotelorism and poorly developed
nose with a single nostril).
27,28
(Table 33-1).
Chapter 33 ■ The Fetal Face and Neck 1173
A
FIGURE 33-7. Sloped forehead in fetus with Wolf-Hirschhorn syndrome and cleft palate. A, Coronal 3-D, and
B, sagittal MR, images show a broad, flat nasal bridge and forehead at 34 weeks’ gestation, the so-called “Greek warrior helmet” facies.
Note sloped forehead (arrow in B) and absence of the secondary palate (arrowhead in B, showing nasopharynx communicating with
oropharynx).
CONDITIONS ASSOCIATED
WITH HYPOTELORISM
Abnormalities of the brain
Holoprosencephaly
Microcephaly
Chromosomal abnormalities
Trisomies 13, 18, and 21
Chromosome 5p deletion
Head shape abnormalities
Trigonocephaly
Syndromes
Langer-Giedion syndrome
Oculodentodigital dysplasia
Nasal maxillary dysostosis (Binder syndrome)
Myotonic dystrophy
Meckel-Gruber syndrome
Williams syndrome
B
CONDITIONS ASSOCIATED
WITH HYPERTELORISM
Chromosomal abnormalities
Trisomy 9p
45,XO
Single-gene disorders
Apert syndrome
Crouzon syndrome
Noonan syndrome
Developmental abnormalities
Craniosynostosis
Anterior encephalocele
Median facial cleft
Megalencephaly
Agenesis of the corpus callosum
Orbital teratoma
Cleft lip
Teratogens
Dilantin
Valproate
Hypertelorism
Hypertelorism is defined as widely spaced eyes (Figs.
33-11 and 33-12; see also Fig. 33-17, E and F). Given
the embryologic development of the eyes and their
migration from a lateral position to midline, hypertelorism may result from abnormalities that interfere
with this normal migration. Large orbits can result in
abnormal orbital measurements; tables provide normal
diameter of the globes.
31
Microphthalmia and Anophthalmia
Abnormally small (microphthalmia) or absent (anophthalmia) orbits are rarely diagnosed on fetal sonography,
but, when present, are frequently associated with
chromosomal abnormalities or syndromes
32,33
(Fig.
33-13). Fetal karyotype analysis should be considered
and a careful search for additional fetal abnormalities
undertaken.
1174 PART IV ■ Obstetric Sonography
A
C
FIGURE 33-8. Sloped forehead in fetus with posterior encephalocele. A and B, 2-D and 3-D sonographic profiles
of a 28-week fetus with microcephaly and a small posterior encephalocele. The sloping forehead (arrow) is caused by a lack of forebrain
development. C, Axial sonogram shows high occipital defect (calipers) through which a small amount of dysplastic brain protrudes.
D, Sagittal MR image shows microcephaly and the high occipital defect in the skull (arrow).
D
B
Coloboma
Coloboma results from incomplete closure of the optic
fissure and most often affects the iris inferiorly
6
(Fig.
33-14). However, it can affect any structure from the
eyelid to the optic nerve or retina. Vision may or may not
be affected, depending on the structures affected and the
severity of the abnormality. Diagnosis in utero depends
on visualization of a focal bulge in the posterior aspect of
the globe. In cases where bones cause artifacts in this
region and this assessment is crucial, 3-D ultrasound
34
or
35
MRI
can be helpful. Coloboma is a rare diagnosis
36
(0.26:1000)
and may be associated with other anomalies
and syndromes, such as CHARGE syndrome (coloboma,
heart defects, choanal atresia, restriction of growth and
development, genital and ear anomalies).
Dacryocystocele
Dacryocystoceles result from obstruction of the nasolacrimal ducts (Fig. 33-15). These present as cystic masses
that may contain low-level internal echoes, located
Chapter 33 ■ The Fetal Face and Neck 1175
TABLE 33-1. NORMAL ORBITAL DIAMETERS IN THE FETUS
GESTATIONAL AGE
Inner Diameters (mm) Outer Diameters (mm)
(wk)
5th %ile 50th %ile 95th %ile 5th %ile 50th %ile 95th %ile
13 4 7 10 12 16 20
14 5 8 11 14 18 22
15 5 8 11 17 21 25
16 6 9 12 19 23 27
17 7 10 13 21 25 29
18 8 11 14 24 27 31
19 8 11 14 26 30 34
20 9 12 15 28 32 36
21 10 13 16 30 34 38
22 10 13 16 32 36 40
23 11 14 17 33 37 41
24 12 14 17 35 39 43
25 12 15 18 37 41 45
26 13 16 19 39 43 47
27 13 16 19 40 44 48
28 14 17 20 42 46 50
29 14 17 20 43 47 51
30 15 18 21 45 49 52
31 15 18 21 46 50 54
32 16 19 22 47 51 55
33 17 20 23 48 52 56
34 17 20 23 49 53 57
35 18 21 24 50 54 58
From Trout T, Budorick NE, Pretorius DH, McGahan JP. Significance of orbital measurements in the fetus. J Ultrasound Med 1994;13:937-943.
Table generated from raw data using two separate quadratic regression models:
Outer diameter Age 0.03 Age= − +
Inner Diameter Age 0.007 Age= − +
2 17 3 36
. .
R20 96 0 001= <. , .p
4 14 0 94
. .
R20 84 0 001= <. ; .p
( )
( )
−
−
( )
( )
2
2
A
B
FIGURE 33-9. Hypotelorism. A, Microtia and hypotelorism. Axial sonogram shows small orbits (arrowheads), close together in
the face, and the protuberant maxilla (arrow). The fetus also had agnathia and low-set ears (see Figs. 33-16, A, and 33-25). B, Hypotelorism and abnormal nose (arrow) at 35 weeks’ gestation. Axial MR image of a 35-week fetus shows the relatively small intraorbital
distance and an abnormal nose. The fetus was in deep vertex prone position, and the face could not be seen on fetal sonography before
MRI. This fetus was diagnosed postnatally with a complex Tessier cleft.
1176 PART IV ■ Obstetric Sonography
A B
FIGURE 33-10. Cyclops and proboscis at 18 weeks’ gestation. A, Transverse scan through the orbit shows fused,
dumbbell-shaped globe (arrow) and small supraorbital nubbin of tissue, the proboscis (open arrow). Only the outer orbital bony margin
is present, and the medial bony walls are absent. B, Cyclops with fused globes, supraorbital proboscis, and absent nose. (Courtesy Margot
Van Allan, MD, Hospital for Sick Children, Toronto.)
A B
FIGURE 33-11. Hypertelorism in fetus at 25 weeks with bilateral cleft lip and palate. A, Axial sonogram shows
hypertelorism (cursors: +, outer orbital diameter; x, inner orbital diameter). B, Coronal MR image shows hypertelorism and bilaterally
absent palatal shelves. Note the absent secondary palate above the tongue (T) with communication of the amniotic fluid between the
oropharynx and nasopharynx.
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