Nuchal Translucency (NT)

Nuchal Translucency (NT)

In the first trimester, the nuchal translucency (NT), instead of the nuchal fold, is used due to its sonographic appearance. NT normally increases with gestation and crown-rump length. It increases with crown-rump length and the median NT increases from 1.2 mm at 11 weeks to 1.9 mm at 13+6 weeks. Thickened NT may be due to fetal cardiac failure, abnormalities of the extracellular matrix, or abnormalities of the lymphatic system.

During the second trimester, NT usually resolves and in a few cases it evolves into either nuchal edema or cystic hygromas with or without hydropic changes. Extensive studies have now established that fetal NT, using the value of the 95th percentile for crown-rump length as a cut-off point, can effectively screen Down’s syndrome with a sensitivity of at least 75% for a false positive rate of <5%. In addition, the thickened NT is also associated with numerous syndromes (e.g. Cornelia de Lange, Noonan syndrome, Smith-Lemli-Opitz syndrome, Apert syndrome) or anomalies in euploid fetuses (e.g. major heart defects, diaphragmatic hernia) , and adverse outcome (early fetal demise) .

Sonographic measurement:

NT can be measured successfully by transabdominal ultrasound in about 95% of cases; in the other cases, it is necessary to perform transvaginal sonography. The average time allocated for each fetal scan should be at least 10 minutes. All sonographers performing fetal scans should be capable of reliably measuring the crown-rump length and obtaining a proper sagittal view of the fetal spine. It is essential that the same criteria are used to achieve uniformity of results among different operators:

  • The minimum fetal crown-rump length should be 45 mm and the maximum 84 mm. The optimal gestational age for measurement of fetal nuchal translucency is 11-13+6 weeks.
  • The results from transabdominal and transvaginal scanning are similar but the reproducibility may be better with the transvaginal method.
  • A good sagittal section of the fetus, as for measurement of crown-rump length, should be obtained.
  • The magnification should be such that the fetus occupies at least three-quarters of the image. Essentially, the magnification should be increased so that the increment in the distance between the calipers should be only 0.1 mm.
  • Care must be taken to distinguish between fetal skin and amnion because, at this gestation, both structures appear as thin membranes. This is achieved by waiting for spontaneous fetal movement away from the amniotic membrane; alternatively, the fetus is bounced off the amnion by asking the mother to cough and/or by tapping the maternal abdomen.
  • The maximum thickness of the subcutaneous translucency between the skin and the soft tissue overlying the cervical spine should be measured by placing the calipers on the lines as shown in Fig.<?which figure?>. During the scan, more than one measurement must be taken and the maximum one should be recorded.
  • The NT should be measured with the fetus in the neutral position. When the fetal neck is hyperextend the measurement can be increased by 0.6 mm and when the neck is flexed the measurement can be decreased by 0.4 mm.
  • The umbilical cord may be around the fetal neck in 5-10% of cases and this finding may produce a falsely increased nuchal translucency, adding about 0.8 mm to the measurement. In such cases, the measurements of NT above and below the cord are different and, in the calculation of risk, it is more appropriate to use the smaller measurement.

The ability to measure NT and obtain reproducible results improves with training; good results are achieved after 80 and 100 scans for the transabdominal and the transvaginal routes, respectively. Appropriate training, high motivation and adherence to a standard technique for the measurement of NT are essential prerequisites for good clinical practice.

In two large multicenter studies of first trimester Down’s syndrome screening, accurate nuchal translucency measurements required stringent training, formalized evaluation of sonographers’ competence, and continuing external quality control. In the latter trial, adequate NT images could not be obtained in 6% of cases.

Nuchal translucency:  Mid-sagittal scan of the fetus at 11 weeks of gestation showing NT and crown-rump length measurements

Thickened nuchal translucency:  Mid-sagittal scan of the fetus at 11 weeks of gestation showing the NT of 3.0 mm

Thickened nuchal translucency :  Sagittal scan of the fetus 10 weeks: cystic lesion (*) on the fetal neck

Early cystic hygroma :  Small non-septate cyst on the back of the neck with early hydrops fetalis (subcutaneous edema)

Early hydrops fetalis:  Sagittal scan of the fetus 13 weeks: generalized subcutaneous edema (arrow) with cystic fluid collection (on the back of the neck) (hydrops fetalis related to cystic hygroma)

Markedly Thickened NT:  Nuchal fluid collection at the posterior aspect of the neck of the fetus with monosomy X

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Nuchal Thickening

Nuchal Thickening

Redundant soft tissue in the back of the neck area has been known to be a feature of newborns and fetuses with Down’s syndrome. A sonographic sign of a thickened nuchal fold is used as a marker of an increased risk of fetal Down’s syndrome in the second trimester, typically after 15-20 weeks of gestation. This measurement has remained the most sensitive and specific single marker for the midtrimester detection of Down’s syndrome.

Sonographic examination:

Fig 1, Fig 2, Fig 3

  • The measurement is done using a transverse section of the fetal head, angled posteriorly to include the cerebellum and the occipital bone. The following landmarks must be identified: cavum septi pellucidi, cerebral peduncles, cerebellar hemispheres and cisterna magma. The measurement is made from the outside of the occipital bone to the outer skin edge.
  • A soft tissue thickening of 6 mm or greater between 15 and 20 weeks of gestation is considered abnormal. However, the 95th percentile of nuchal fold thickness measured by transvaginal sonography at 14-16 weeks is 3.0 mm.
  • The observer variability for this measurement is only 1 mm among experienced practitioners.
  • Combining second trimester serum testing and nuchal fold thickness is substantially more effective than either serum screening or ultrasound alone.

Fig 1:  Nuchal edema  Transcerebellar view of the skull: thickening of nuchal fold 

Fig 2:  Nuchal edema  Transcerebellar view of the skull: normal cisterna magna (*), thickening of nuchal fold (arrow)

Fig 3:  Nuchal edema   Transcerebellar view of the skull: marked thickening of nuchal fold (arrowhead) (arrow = occipital bone) 

Video clips of nuchal thickening

Nuchal thickening:  Transcerebellar plane: thickened nuchal fold (arrowhead) (arrow = occipital bone)

Nuchal thickening:  Transcerebellar plane: thickened nuchal fold (arrow)

Nuchal thickening :  Transcerebellar plane: thickened nuchal fold (arrow)

Nuchal thickness along with other sonomarkers during 15-20 weeks is incorporated into the sonographic scoring index for detection of Down’s syndrome in the second trimester as follows:

Sonographic index for Down’s syndrome in second trimester fetuses

Findings                                                 Score

Major anomaly                                          2

Nuchal fold >6 mm                                   2

Short femur                                               1

Short humerus                                           1

Pyelectasis                                                 1

Hyperechoic bowel                                   1

Echogenic intracardiac focus                    1

  • This genetic sonogram scoring index was used to identify approximately 75% of fetuses with Down’s syndrome, with amniocentesis being recommended in 26.7% of a high-risk population.
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Proboscis

Other Abnormalities

Fig 1: Small nose   Small nose related to fetal trisomy 13

Fig 2: Abnormal ear shape  Abnormal ear shape in association with Down syndrome 

Fig 3:  Macroglossia  Facial profile view: persistent protruding tongue (arrow) (in fetal Down syndrome)

Video clips of other abnormalities

Cataract:  Coronal scan of the face shows hyperechoic lens (arrow) (arrowhead : chin)

Other rare disorders of the head/neck may be found on facial examination such as cataract, absent or small nose, abnormal facies, or abnormal ear configuration.

Fig 1, Fig 2, Fig 3

Diprosopus

Diprosopus is a very rare form of conjoined twins, consisting of a single neck and body and a spectrum of duplication of craniofacial structures, ranging from isolated duplication of the nose to complete facial duplication.

Sonographic findings:

  • Two faces with a fused head, fused neck.
  • One nose or two noses, four orbits or three orbits (the middle two orbits are fused together).
  • Double lines of spinal cords, but only one set of other structures.
  • Abnormally-shaped skull.
  • Disorganized intracranial structure.
  • Two pairs of thalami is common.

Associations: Duplication disorders in several structures.

Management: Termination of pregnancy should be offered.

Prognosis: Poor.

Recurrence risk: Rare.

Cataract

Cataracts can develop in fetuses infected with TORCH and can be associated with a number of syndromes. The prenatal diagnosis of cataracts has been made largely among patients at increased risk for cataracts in their offspring. The ultrasound findings are a small round echogenic mass in the anterior aspects of the eye, in which the usually thin-walled, rounded, cystic lens appears solid and completely echogenic.

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Other Neck Masses

Other Neck Masses

Cervical teratoma:  Sagittal scan of the thorax and neck: solid-cystic mass (*) lateral to the neck (arrowhead = spine)

Fetal goiter :  Large complex mass at the anterior aspect of the neck, postnatally proven to be goiter

Cervical Teratomas

Teratomas are neoplasms derived from pleuripotent cells and are composed of a diversity of tissues foreign to the anatomic site in which they arise.

Incidence: Rare, may be 1 in 20,000 to 1 in 40,000 live births. It most commonly occurs in the sacrococcygeal area and the neck accounts for about 5% of teratomas.

Sonographic findings:

  • Typically, solid cystic, beginning with cystic masses and becoming larger and more complex with gestational age.
  • Usually unilateral with an anterolateral location.
  • Calcification seen in nearly half of the cases.
  • Sometimes hyperextension secondary to a pressure effect of the large mass.
  • Hydrops fetalis and hydramnios noted in 30% of cases.
  • Three-dimensional ultrasound and color Doppler ultrasound showing intense arterial and venous flow with low resistance indices may be helpful.
  • The main differential diagnoses include lymphangioma, hemangioma, or goiter.

Associations: Rarely related to other anomalies.

Management: Fetal resection or termination of pregnancy may be offered for a large mass with hydrops before viability. Cesarean section should be considered in the case of a large mass. The ex utero intrapartum treatment (EXIT) or operation on placenta support (OOPS) has been proposed in cases of potential airway obstruction.

Prognosis: Benign in more than 90% of cases but there is a high mortality rate mainly due to respiratory obstruction, prematurity and hydrops fetalis; definitive surgery may result in good outcome.

Recurrence risk: Rare.


Cervical meningomyelocele

(See spina bifida.)

Occipital Cephalocele

(see details in Part I)

Hemangioma/Lymphangioma

Hemangioma is a proliferation of vascular endothelium that may occur anywhere in the body including the face and neck, although this is relatively rare. Lymphangioma is a congenital malformation of lymphatic vessels. Hemangioma and lymphangioma show overlapping pathologic and sonographic features.

Incidence: Rare in fetal life, but rather common during the first year of life.

Sonographic findings :

  • Variable depending on types of hemangiomas; capillary, arteriovenous, or venous angiomas.
  • Hemangiomas: solid appearance due to numerous small vascular channels in most cases, but mixed solid and cystic masses are also seen.
  • Small internal hypoechoic spaces are occasionally seen.
  • Positive Doppler signal or demonstration of vascularization is helpful in the diagnosis of hemangioma.
  • Lymphangiomas: cystic mass with multiloculated areas in most cases.
  • High-out heart failure or hydrops fetalis may be noted in massive hemangioma.

Associations: Usually isolated abnormalities.

Management: In general, hemangioma/lymphangioma does not alter the standard obstetric management. Postnatal surgical correction is required for persistent cases.

Prognosis: Generally good, but prompt airway management is required in massive cases; postnatal spontaneous regression can be observed in 60% of hemangiomas.

Recurrence risk: Rare.


Goiter

Goiter is an enlarged thyroid gland, probably associated with maternal ingestion of iodides or antithyroid drugs or maternal Graves’ disease.

Incidence: Rare.

Sonographic findings:

  • Typically solid and homogeneous but occasionally hypoechoic mass which is considered abnormal if it is 2 SD above normal.
  • Symmetrical, bilobed, located at the anterior neck.
  • Hyperextension of the fetal head may be noted in cases of large mass.
  • Polyhydramnios presumably due to impaired swallowing may be observed.
  • High-output cardiac failure with cardiomegaly and pleural effusion or hydrops fetalis may occasionally occur.
  • MRI is helpful in identifying thyroid tissue.
  • The main differential diagnoses include cervical teratoma and hemangioma.
  •  Usually diagnosed in the third trimester or late second trimester.

Associations: Usually isolated.

Management: If sonographically diagnosed, accurate diagnosis of fetal thyroid status should be obtained by fetal blood sampling and intrauterine therapy may be initiated, either by reduction of maternal antithyroid medication, or intra-amniotic injection of levothyroxin in hypothyroidism, and on administration of antithyroid drugs in hyperthyroidism.

Prognosis: Good with appropriate management, however, cretinism and mental retardation secondary to hypothyroidism can occur.

Recurrence risk: Rare.

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Cystic Hygroma

Cystic Hygroma

A congenital malformation of the lymphatic system, which most commonly develops from jugular lymph sac obstruction and enlargement at the posterior triangles of the neck. It is the most common mass of the neck.

Incidence: 1 in 1000 live births but 1 in 200 abortuses.

Natural history: Either an isolated finding or part of a syndrome, such as Turner syndrome, or trisomy 21, 18 and 13. Two-thirds of cases are related to chromosome abnormalities.

    Fig 1,

Fig 1: Schematic drawing: Normal lymphatic system compared to that of cystic hygroma

Sonographic findings:

Fig2, Fig3, Fig4

  • Septated or non-septated cystic mass without a solid component in the mass.
  • Typically, a symmetric or bilateral cystic structure with one or more septations, located in the posterior neck area.
  • Dense midline septum, nuchal ligament.
  • Normal cranial contents and skull as well as intact cervical spine, unlike meningocele.
  • Diffuse hydrops and oligohydramnios in severe cases.
  • The main differential diagnoses are cephalocele, cervical meningocele, cystic teratoma, and hemangioma.
  • First diagnosable late in the first trimester, and usually early in the second trimester.

Fig 2:  Cystic hygroma  Oblique cross-sectional scan at the level of cerebellum: anechoic cyst (arrow) with central septum

Fig 3: Cystic hygroma  Oblique coronal scan at the neck: multiple anechoic cysts with thickened septum at the posterior aspect of the neck

Fig 4:  Cystic hygroma with hydropic changes  Cross-section scan of the abdomen: anechoic cysts (solid circle) in subcutaneous edema (extending from the neck area) (* = ascites) 

Video clips of cystic hygroma

Cystic hygroma:  Septate cystic mass (*) on the back of the neck

Large cystic hygroma:  Large septate cyst on the back of the neck

Cystic hygroma:  Coronal scan of the fetal trunk: multiple cystic areas (*) around the neck as well as ascites (solid circle)

Early cystic hygroma:  Small non-septate cyst on the back of the neck with early hydrops fetalis (subcutaneous edema)

Early hydrops fetalis:  Sagittal scan of the fetus 13 weeks: generalized subcutaneous edema (arrow) with cystic fluid collection (on the back of the neck) (hydrops fetalis related to cystic hygroma)

Associations: About 60-70% of fetuses with cystic hygroma have aneuploidy, especially 45,XO, and trisomy 21, 18 and 13. The risk of aneuploidy is higher when the cyst is septated, and therefore large. Cystic hygroma in the first trimester is less likely to be associated with aneuploidy, and trisomy 21 is the most common. Compared to non-septated cystic hygromas, septated cystic hygromas are more likely to persist and be associated with aneuploidy, hydrops and other anomalies, and pregnancy loss. Turner syndrome, which is often related to cystic hygroma, may be associated with coarctation of aorta or other anomalies such as horse shoe kidneys, and widespread anatomic disruption due to hydrops.

The 45,X karyotype was found only in patients with septated hygromas and was present in 77% of cases. In contrast, trisomy 21 was the most common abnormal karyotype in non-septated lesions (31%).

Management: Careful search for associated anomalies and karyotyping should be performed. Termination of pregnancy should be considered if associated with chromosomal abnormalities or hydrops fetalis. Isolated cases need follow-up ultrasound study. Intrauterine injection of OK-432 was reported to be a safe and effective therapy in some cases.

Prognosis: Good in mild isolated cases in which spontaneous resolution can occur, but very poor if associated with chromosome abnormalities or hydrops fetalis. Sixty percent of affected fetuses develop signs of hydrops (e.g. ascites, pleural effusions, and edema).

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Cleft lip / Palate

Cleft Lip/Palate

Natural history: multifactorial (more than 90%), part of several syndromes or chromosome abnormalities in <10%, most are trisomy 18 and 13.

Clefts are classified into five categories:

  • Type 1, cleft lip alone; a lower rate of anomalies (20%)
  • Type 2, unilateral cleft lip and palate; intermediate prognosis
  • Type 3, bilateral cleft lip and palate; intermediate prognosis
  • Type 4, midline cleft lip and palate; a high rate of concurrent anomaly, fatal outcome
  • Type 5, slash type; facial defects associated with amniotic bands or limb-body wall complex; a high rate of concurrent anomaly, fatal outcome.

Incidence: 1 in 1000 live births but much more common among prenatal series.

  • Isolated lesion accounting for about two-thirds of clefts and about one-third have associated abnormalities.
  • Isolated cleft lip and/or palate in 0.8 per 1000 births (cleft lip alone 0.3, cleft lip and palate 0.5 per 1000). There is marked ethnic and racial variation. Non-Hispanic Whites had the greatest prevalence of isolated clefts, Asians had a slightly lower prevalence, and Blacks had the lowest prevalence.
  • Isolated cleft palate (distinct disorder); 0.31 per 1000 births. Asians had the lowest prevalence of CP; in Whites and Hispanics it was almost twice as high.

Sonographic findings:

Fig 1, Fig 2, Fig 3, Fig 4

  • Defect of the upper lip which is most easily detected in the coronal view.
  • Cleft palate best diagnosed by showing disruption of the C-shaped alveolar ridge of the maxilla in the axial view.
  • In the presence of a bilateral cleft lip/palate a mass of soft tissue (premaxillary protrusion) protrudes anteriorly residing beneath the nose.
  • A maxillary protrusion best visualized in the sagittal plane.
  • Most fetuses with bilateral cleft lip and palate often show a protuberant premaxillary segment, a midline echogenic soft tissue mass just below the nose, whereas some have no premaxillary segment but show a flattened nose instead.
  • Midline clefts: an absence of the central maxilla and upper lip with a deformed or small or absent nose, commonly associated with proboscis.
  • Slash types: asymmetric random defects caused by amniotic bands.
  • 3D ultrasound or MRI may be ancillary to conventional ultrasound in prenatal diagnosis of the facial cleft, allowing a better staging of the lesion by demonstrating the degree of involvement of the palate.
  • Pitfalls:
    • For isolated clefts, the detection rate for isolated lesions varies among studies from 18 to 75%.
    • Normal philtrum can sometimes be confused with a midline cleft lip.
    • Premaxillary protrusion associated with bilateral cleft can be confused with other facial masses.
    • Bilateral clefts without premaxillary segment are likely to be confused with large midline cleft.

Median cleft lip   Coronal view of the face: median cleft lip in fetal trisomy 13

Paramedian cleft  Sagittal view of the face: paramedian cleft lip

Median cleft lip  Coronal view of the face: median cleft lip in fetal trisomy 13

Paramedian cleft  Coronal view of the face: paramedian cleft lip (arrow)

Video clips of cleft lip / palate

Cleft lip:  Coronal scan of the face: small paramedial cleft (arrow)

Cleft lip:  Coronal scan of the face: paramedial cleft (arrow)

Bilateral cleft lips :  Coronal scan of the face: bilateral paramedial cleft (arrow)

Cleft lip and palate :  Transverse scan of the face: incomplete alveolar ridge (*) of the maxilla

Midline cleft lip:  Coronal scan of the face: midline cleft (arrow) (arrowhead = lens in the orbit)

Associations: One-third of the fetuses with clefts are associated with other anomalies, including more than 250 syndromes, especially central nervous system and cardiac anomalies. Chromosomal abnormalities are seen in about 10%, especially trisomy 18 and 13. Midline clefts, accounting for <1% of all facial clefts, are commonly related to holoprosencephaly and trisomy 13.

Management: Careful prenatal and postnatal search for associated anomalies is required. All continuing pregnancies should be karyotyped. Serial sonography should be performed. Antenatal diagnosis and antenatal counseling are very important for either planned postnatal therapy or termination in cases with fatal anomalies.

Prognosis: Good unless other severe anomalies are present. Poor prognosis when related to other anomalies and chromosomal abnormalities.

Recurrence risk: For isolated cases, 4% of recurrent risk with one affected sibling, 9% with two affected siblings, 4% with one affected parent and 17% with one affected sibling and one affected parent. Folic acid supplementation may decrease the risk of recurrence.

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Holoprosencephaly

Holoprosencephaly

(Also see details anomalies of the fetal head)

Briefly, holoprosencephaly is a complex spectrum secondary to absent or incomplete median cleavage of the forebrain and ventricular system, resulting in a monoventricular cavity and abnormal midline structures. In addition to the major abnormalities in the brain, facial deformities are also very common.

Fig1, Fig2, Fig3, Fig4, Fig5, Fig6, Fig7

These deformities are as follows:

  • Orbits:
    • hypotelorism; abnormally close spacing of the orbits
    • cyclopia; single midline orbit
  • Nose:
    • proboscis with absent nose
    • ethmocephaly; hypotelorism; absent nose; proboscis may be single or double or absent
    • cebocephaly; hypotelorism, single nostril nose
  • Upper lip:
    • midline cleft; flat nose; premaxillary agenesis
    • lateral cleft (rare).

Fig 1: Schematic drawing: Facial abnormality related to holoprosencephaly: Ethmocephaly

Fig 2: Schematic drawing: Facial abnormality related to holoprosencephaly: Cyclopia with proboscis

Fig 3: Schematic drawing: Facial abnormality related to holoprosencephaly: Normal face

Fig 4: Schematic drawing: Facial abnormality related to holoprosencephaly: Bilateral clefts

Fig 5: Schematic drawing: Facial abnormality related to holoprosencephaly: Midline cleft

Fig 6: Schematic drawing: Facial abnormality related to holoprosencephaly: Cebocephaly

Fig 5:Holoprosencephaly and proboscis  Transverse scan of the skull showing common ventricle (*) and oblique coronal scan the proboscis (solid circle = thalamus, arrow = orbits, arrowhead = proboscis)

Video clips of proboscis

Proboscis:  Coronal scan of the face showing a proboscis above the cyclopia

Proboscis:  Mid-sagittal scan of the face showing a proboscis above the eye with absent nose

Proboscis (holoprosencephaly): Midline solid mass at the forehead (proboscis) and fused ventricle

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Proboscis

Proboscis

Proboscis, abnormal nose formation, is almost always related to hypotelorism and holoprosencephaly. The sonographic findings reveal an appendage with one or two openings which replaces the nose. It is located midline at the level of orbit, upper or lower, and is usually diagnosed in the second trimester but possibly in the first trimester. Associated abnormalities include holoprosencephaly, hypotelorism or cyclopia, cebocephaly, and abnormal chromosome, especially trisomy 13. The use of 3D prenatal US made additional diagnostic images possible.

Lateral nasal proboscis is a rare anomaly resulting in incomplete formation of one side of the nose and other variable abnormalities in the adjoining regions of the face, without associated brain malformations. With careful examination, it can also be diagnosed antenatally.

Fig 1, Fig 2, Fig 3, Fig 4, Fig 5, Fig 6

The main differential diagnoses are midline abnormal masses such as

  • Anterior cephalocele
  • Hemangioma

Fig 1: Schematic drawing: Facial abnormality related to holoprosencephaly: Ethmocephaly

Fig 2: Schematic drawing: Facial abnormality related to holoprosen-cephaly: Cyclopia with proboscis

Fig 3: Schematic drawing: Facial abnormality related to holoprosencephaly: Cebocephaly

Fig 4: Proboscis  Facial profile view: proboscis and absent nose

Fig 5: Proboscis and cyclopia  Transverse scan of the skull at the level of orbits: fused orbit (*) and proboscis

Fig 6: Proboscis  Sagittal-coronal view: proboscis cyclopia (solid circle) and absent nose

Video clips of proboscis

Proboscis:  Mid-sagittal scan of the face showing a proboscis above the eye with absent nose

Proboscis:  Coronal scan of the face showing a proboscis above the cyclopia

Proboscis:  Coronal scan of the face: arrowhead = forehead, arrow = proboscis)

Proboscis:  Facial profile view shows proboscis in a case of holoprosencephaly, note: absent nose

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Micrognathia

Micrognathia

Micrognathia, an abnormally small lower jaw and receding chin, is a rare condition often related to a specific syndrome (Pierre Robin syndrome; occurring in 1 in 30,000 people). The prenatal diagnosis is usually made subjectively on the facial profile view with demonstration of a small, receding chin and the lower lip may reside posterior to the upper lip. The objective assessment, either mandibular length or jaw index, is helpful in subtle cases. Normative data are available. Polyhydramnios due to obstruction of the small oropharynx is very common.

Micrognathia can objectively be assessed through the calculation of the mandible width/maxilla width ratio on axial views obtained at the alveolar level. Mandible and maxilla widths were measured 10 mm posteriorly to the anterior osteous border.

Fig 1, Fig 2, Fig 3

The major causes of micrognathia are as follows:

  • Trisomy 18 (most common, but subtle degrees in several cases)
  • Trisomy 13
  • Pierre Robin syndrome (combined with cleft palate and glossoptosis)
  • Treacher Collins syndrome
  • Skeletal dysplasia (campomelia, osteochondrodysplasia, short-rib syndrome)
  • Pena-Shokeir phenotype
  • Treacher Collins syndrome (mandibulofacial dysostosis)
  • Disorder related to lack of mandibular movement, e.g. Pena-Shokeir phenotype (normal mandibular growth may depend on the presence of mandibular movement during intrauterine development).

Fig 1: Micrognathia  Facial profile view shows receding jaw

Fig 2: Micrognathia  Facial profile view shows receding jaw

Fig 3: Micrognathia  Facial profile view shows receding jaw

Video clips of facial clefts

Micrognathia  Facial profile view shows receding jaw (arrow)

Micrognathia:  Facial profile view shows small mandible (arrow)

Micrognathia :  Facial profile view shows markedly small chin (arrowhead) of the fetus with trisomy 13

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Facial Clefts

Macroglossia

Macroglossia, a big tongue, is a rare condition mostly related to specific syndromes. The most common syndrome associated with macroglossia is Beckwith-Wiedemann syndrome, and it is sometimes associated with trisomy 21. Macroglossia can be best visualized on the facial profile view. The coronal view is also helpful. A nomogram for tongue measurement has been established.

Fig 1

The major causes of macroglossia are as follows:

  • Beckwith-Wiedemann syndrome
  • Athyrotic hypothyroidism
  • Trisomy 21, 22
  • Autosomal dominant macroglossia
  • Harlequin fetus (congenital ichthyosis)
  • Mass of the tongue; lingual thyroid, lingual hemangioma, lymphangioma
  • Epignathus.

 

Fig 1: Macroglossia   Facial profile view: persistent protruding tongue (arrow) (in fetal Down syndrome)

Video clips of facial clefts

Macroglossia: Midsagittal facial profile shows persistent protrusion of the enlarged tongue

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