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4.3 Integrity ofthePalate
23
Normal a
Sagittal
bc
NB
VB
Unilateral Bilateral
M
P
Median
d
Isolated
Coronal Axial
Fig. 4.7 Line diagram illustrating the utility of sagittal,
axial, and coronal planes in the evaluation of palatine
clefts. The sonographic appearance of the (a) midsagittal
view, (b) parasagittal view, (c) axial view and (d) coronal
for assessing palatine clefts can be avoided by
assessing the palate in all three planes [5].
Figure 4.7 is a line diagram from our study
illustrating the salient landmarks to be evaluated
in sagittal, axial, and coronal views in normal and
in various palatine clefts [5]. Most often, these
view in the intact palate are illustrated. The diagnostic
markers in sagittal, axial, and coronal views to identify
different types of palatine clefts are shown
2D markers can well be appreciated in a routine
transabdominal scan. However, the usage of the
transvaginal route is recommended when there is
a suspicion of an abnormality or when there is
difculty in visualization with the transabdominal route.
24
4 Sonoanatomy ofPalate at11–14Weeks
4.4 Ossication ofthePalate
Figures 4.8, 4.9, 4.10, 4.11, and 4.12 are an illustration of the appearance of the normal palate
from 10 to 14weeks of gestation. Embryologically
ossication of the secondary palate commences
from 11weeks of gestation, and there is progressive ossication of the palate as gestation age
advances. Figure4.8 depicts a normal physiological maxillary gap at 10weeks of gestation. The
maxillary gap gets obliterated once the primary
palate fuses with the secondary palate.
Figure 4.9 shows the normal anatomical landmarks of the palate in sagittal, axial, and coronal
a
view at 11weeks of gestation. Note the presence
of the maxillary gap in the sagittal view
(Fig.4.9c). However, after 12–13weeks of gestation, the physiological maxillary gap is not seen.
By 13 to 14weeks of gestation, there is suf-
cient ossication to evaluate the palate.
Figures4.10, 4.11 and 4.12 illustrate the anatomical landmarks of the palate at 12, 13, and
14weeks of gestation respectively.
Though there is less shadowing in the rst trimester compared to mid trimester, still the shadowing from the premaxilla can hinder
visualization of the secondary palate as shown in
Fig.4.13a. The shadowing can be mistaken for
b
c
Fig. 4.8 Physiological maxillary gap in normal palate at
10 weeks early gestation (TVS). (a) Sagittal section,
physiological maxillary gap (arrow). (b) 3D Midsagittal
image showing the maxillary gap (arrow) at the junction
of the primary and secondary palate. (c) Multiplanar display of the palate in sagittal and coronal views, maxillary
gap (arrow) premaxilla (arrowhead)
4.4 Ossication ofthePalate
25
a
D 4.55 cm
b
c
B
Fig. 4.9 Physiological maxillary gap at 11weeks (TAS) (a) CRL of 45mm. (b) Midsagittal view of the face with
maxillary gap (arrow). (c) Coronal view of the fetus showing the intact base of the retronasal triangle (B)
the absence of a maxillary line leading to a
false-positive diagnosis. The maxillary line can
be imaged in the neutral position in the same case
with minimal shadowing, as shown in Fig.4.13b.
From 14weeks onwards, the hard palate and the
developing soft palate can be visualized with the
fetal neck in the slight extension and with uid in
the oral cavity (Fig.4.13c).
Sometimes a small artifactual gap can be seen
in the healthy fetus at the proximal junction of
the superimposed vomer bone with the secondary
palate (Fig.4.14). The gap is due to shadowing
from the proximal edge of the vomer and is seen
in the anterior one-third region of the maxillary
line (Fig.4.14 a1) [4]. Transabdominal and transvaginal images in the same case with and without
an artifactual gap is shown in Fig.4.14b and b1.
However, this gap that is seen is almost always
very small and disappears with a change in the
angle of insonation of the ultrasound beam.
26
4 Sonoanatomy ofPalate at11–14Weeks
a
c
b
NB
ML
M
V
P
d
F
Fig. 4.10 Sonographic visualization of the palate at
12weeks. (a) (TAS) CRL of 55mm. (b) (TAS) midsagittal view, intact maxillary line (ML) (c) (TAS) coronal
view intact base of the retronasal triangle (arrow). (d)
(TVS) Axial view continuity of the alveolar arch of the
maxilla (arrows), uid (F) in the oropharynx. Nasal bone
(NB), mandible (M), vomer (V) and Palate (P)
4.4 Ossication ofthePalate
27
a
c
*
b
NB
ML
M
V
P
d
F
Fig. 4.11 Sonographic visualization of the palate at
13weeks. (a) (TAS) CRL of 68mm. (b) (TAS) midsagittal view, the intact maxillary line (ML), (c) (TAS) coronal
view intact base of the retronasal triangle (*). (d) (TVS)
Axial view continuity of the alveolar arch of the maxilla
(arrows), uid (F) in the oropharynx. Nasal bone (NB),
Mandible (M), Palate (P) and vomer (V)
28
4 Sonoanatomy ofPalate at11–14Weeks
a
c
b
NB
ML
V
M
P
d
P
*
Fig. 4.12 Sonographic visualization of the palate at
14weeks (TAS). (a) CRL of 82mm. (b) Midsagittal view,
intact maxillary line (ML), (c) Coronal view intact base of
the retronasal triangle (*). (d) Axial view continuity of the
alveolar arch (arrows) and the bony hard palate (P). Nasal
bone (NB), Mandible (M), Palate (P) and Vomer (V)
4.4 Ossication ofthePalate
29
a
b
ML
*
c
HP
SP
Fig. 4.13 Pitfalls in visualizing maxillary line.
(14weeks) (a) TVS midsagittal view of the fetal face in
slight extension with shortened maxillary line due to
shadowing (*) by premaxilla (dashed arrow), (b) TAS
midsagittal view of face in exion showing the normal
maxillary line (ML) in the same case, (c) TVS illustration
of the complete maxillary line with fetus in extension
denoting the bony hard palate (HP) and developing soft
palate (SP). The soft palate lies at an angle to the hard palate (arrow)
30
4 Sonoanatomy ofPalate at11–14Weeks
a
ML
b
ML
a1
V
P
b1
ML
Fig. 4.14 Artifactual maxillary gap in two cases. (a) 13+5
weeks TAS midsagittal section illustrating the intact maxillary line with no gap. (a1) TVS midsagittal section
shows a small maxillary gap in the same case (arrow);
note that the gap is seen at the anterior edge of vomer at
References
1. Maarse W, Pistorius LR, Van Eeten WK, Breugem CC,
Kon M, Van den Boogaard MJ, Mink van Der Molen
AB.Prenatal ultrasound screening for orofacial clefts.
Ultrasound Obstet Gynecol. 2011 Oct;38(4):434–9.
2. Campbell S. Prenatal ultrasound examination of
the secondary palate. Ultrasound Obstet Gynecol.
2007;29:124–7.
3. Lakshmy SR, Rose N, Masilamani P, Umapathy
S, Ziyaulla T. Absent ‘superimposed-line’sign:
novel marker in early diagnosis of cleft of fetal secondary palate. Ultrasound Obstet Gynecol. 2020
Dec;56(6):906–15.
4. Chaoui R, Orosz G, Heling KS, Sarut-Lopez A,
Nicolaides KH.Maxillary gap at 11–13 weeks' gesta-
the junction of anterior one-third and posterior two-thirds
of maxillary line. (b) TVS midsagittal section shows an
intact maxillary line (ML) (b1) midsagittal section in the
same case shows a small gap arrow points to artifactual
gap due to shadowing from the vomer
tion: marker of cleft lip and palate. Ultrasound Obstet
Gynecol. 2015 Dec;46(6):665–9.
5. Lakshmy SR, Deepa S, Rose N, Mookan S, Agnees
J. First-trimester sonographic evaluation of palatine
clefts: a novel diagnostic approach. J Ultrasound Med.
2017 Jul;36(7):1397–414.
6. Lakshmy SR, Rose N, Masilamani P, Umapathy S,
Ziyaulla T.First trimester ultrasound evaluation of the
cleft palate: midsagittal, axial or coronal view-which
view is best? J Fetal Med. 2020 Sep;7(3):183–91.
7. Wilhelm L, Borgers H. The ‘equals sign’: a novel
marker in the diagnosis of fetal isolated cleft palate.
Ultrasound Obstet Gynecol. 2010 Oct;36(4):439–44.
8. Sepulveda W, Wong AE, Martinez-Ten P, PerezPedregosa J. Retronasal triangle: a sonographic landmark for the screening of cleft palate in the rst trimester.
Ultrasound Obstet Gynecol. 2010 Jan;35(1):7–13.
Signs andMarkers in theDetection
ofFirst-Trimester Palatine Clefts
5
Screening for major fetal defects in the rsttrimester 11–14 week scan can identify nearly
half of all anomalies [1]. But still, the detection
rates vary substantially between different studies,
from less than 20% to up to 85% [1, 2]. To standardize the rst-trimester anomaly scan, the
International Society of Ultrasound in Obstetrics
and Gynecology has recently published guidelines for documenting these anatomical structures in early gestation [3].
The suggested anatomy for the assessment of
facial defects includes the evaluation of fetal prole and lips [3]. Recent years have witnessed a
lot of research in this domain with newer signs
and markers to identify cleft palate [4]. A few
markers which would raise a suspicion of palatine clefts have been dealt with in this chapter.
5.1 Maxillary Gap Sign
The maxillary gap sign described by Chaoui etal.
is visible in the midsagittal plane of the fetal face,
which is used routinely for the measurement of
nuchal translucency. This sign has potential value
in the early diagnosis of CLP [5]. In cases of a
maxillary gap, the sonographer should undertake
a detailed examination of the face and palate
regions.
Supplementary Information The online version of this
chapter (https://doi.org/10.1007/978- 981- 16- 4613- 3_5)
contains supplementary material, which is available to
authorized users.
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
L. R. Selvaraj, T. Ziyaullah, First and Mid Trimester Ultrasound Diagnosis of Orofacial Clefts,
https://doi.org/10.1007/978-981-16-4613-3_5
As explained in the previous chapter, the maxillary line in midsagittal view is formed by the
fusion of the premaxilla, the secondary palate,
and the vomer (see Chap. 4, Fig. 4.3). Depending
on the type and extent of the cleft, portions of
the maxillary line are absent, which presents as
a maxillary gap to the sonographer.
Figure 5.1 is a line diagram illustrating the
intact maxillary line and the gap. Figure 5.2
depicts the maxillary gap in the midsagittal view
in bilateral and median cleft lip and palate. In
Fig.5.2a the maxillary gap is visualized between
the premaxilla and the vomer. Video 5.1 illustrates the maxillary gap and the premaxillary protrusion in a case of bilateral CLP. Figure 5.2b
illustrates the absence of the premaxillary portion
in the case of median CLP.
The lack of ossication explains the nding of
a small gap lesser than 1.5mm in healthy fetuses
in the study by Chaoui etal. Hence, a small max-
illary gap in the midsagittal view in the presence
of an intact maxilla in the axial and coronal
view can be considered as a normal nding [5].
5.2 Retronasal Triangle Sign
Sepulveda etal. proposed the use of the retronasal triangle for the detection of cleft palate and
micrognathia [6, 7]. The three echogenic lines in
the retronasal triangle are formed by the two
frontal processes of the maxilla and the palate.
The triangle is visualized in the coronal view of
31
32
ab
ab
NB
ML
Fig. 5.1 Line diagram illustrating (a) intact maxillary line. (b) Maxillary gap in the fetus with cleft lip and palate
5 Signs andMarkers in theDetection ofFirst-Trimester Palatine Clefts
M
V
Fig. 5.2 Appearance of the maxillary gap in cleft palate.
+3
(a) 13
weeks (TVS) midsagittal section in bilateral CLP,
maxillary gap (arrow) and premaxillary protrusion (arrowhead), vomer (V). (Video 5.1) (b) 12weeks (TVS) mid-
the fetal face posterior to the nose. This anatomical landmark is similar to the “premaxillary triangle” described by Suresh etal. [8].
Figure 5.3a illustrates the intact base of the
retronasal triangle, depending on the cleft type,
there can be a midline or lateralized defect
in the base of RNT as shown in Fig.5.3b, c
respectively.
sagittal section in median CLP with the absence of the
proximal portion of the maxillary line (arrows points to
defect)
the ossied upper posterior palatine process to
the anterior ossied portion of the maxilla [9].
The ndings of this study demonstrate that in the
midsagittal view of the fetal face at 11–13weeks
of gestation, the PMD normally increases with
CRL.
In fetuses with isolated CP, compared to nor-
mal fetuses, the PMD is lower. The shortening of
V
the maxillary line can be explained by the fact
that the secondary palate is decient, and hence
5.3 Palatino-Maxillary Diameter
PMD appears smaller. Figure5.4a, b illustrates
the appearance of maxillary line in normal and in
The Palatino-maxillary diameter (PMD)
described by Lachmann etal. is measured as the
shortest hyperechogenic distance, starting from
a case of isolated cleft palate, respectively. Video
5.2 shows the shortening of the maxillary line in
real-time imaging when one moves to and fro