Fetal Facial Sonography: Key Views & Anomalies

• Fetal face and neck anatomy and potential abnormalities can be assessed using sonography, particularly during the late first trimester to early second trimester.

Embryology

• Development of the face and palate occurs around the 6th week.
• By the 28th day, the frontonasal, maxillary, and mandibular prominences are visible with lens and nasal placodes, plus the stomodeum.
• Key facial features develop between the 28th and 40th days.
• By the 40th day, eyelids, nostrils, and the lower jaw are forming
• By the 48th day, the medial nasal prominences are merging with each other and the maxillary prominences.

Sonographic Points

• Features of the fetal face can be identified at the end of the first trimester.
• A profile can be well imaged with TV sonography from late first trimester to early second trimester.
• A modified coronal view is best to image cleft lip and palate.
• The longitudinal view demonstrates the nasal bones, soft tissue, and mandible to rule out micrognathia, anterior encephalocele, or nasal bridge defects; also examines the upper lip.
• Transverse view helps identify orbital abnormalities and intraorbital distances, evaluates the maxilla, mandible, and tongue.

Sonographer Evaluation

• Sonographers should evaluate whether orbits are normally spaced.
• Check if the nose and nasal bridge are clearly imaged and if proboscis or cebocephaly is present.
• Check for periorbital masses.
• Check that the upper lip is intact and the tongue is of normal size.
• Check if the chin is abnormally small.
• Check if the patient's ears are of normal size and position.
• Cebocephaly is a developmental anomaly with a monkey-like head, a defective, flattened nose with a single nostril or absent nose, and closely set eyes.
• Cebocephaly is part of holoprosencephaly.

Normal Anatomy

• The upper lip and nostrils are best visualized in an oblique, coronal plane when looking for facial clefts or proboscis.

Fetal Eye Examination

• Eyes can be imaged in true coronal or transverse planes.
• Measurements of the outer orbital distance are valuable in diagnosing hypotelorism or hypertelorism.
• Inner orbital distances are also useful.
• The lens of the eye appears as a hyperechoic ring with an anechoic central portion.
• Presence and size of both eyes should be documented to exclude microphthalmia (small eyes) and anophthalmia (absent eyes).
• Masses of the orbit and eye can be excluded with careful scanning.
• Periorbital masses like lacrimal duct cysts, dermoids, and hemangiomas can occur.
• Early cataracts appear as the substance of the lens becomes more echogenic, with prominent boundary echoes.

Fetal Nose Examination

• The presence of and length of the nasal bone should be noted.
• Hypoplastic or absent nasal bones are associated with Trisomy 21.
• The average length for a "normal" nasal bone is 4.6 mm, but determination of normalcy is based on gestational age (GA).

Fetal Neck Examination

• Soft tissue structures of the neck may be evaluated in sagittal and transverse planes.
• Pay attention to the contour of the neck.
• A nuchal fold exceeding 6 mm between 15 and 21 weeks is associated with trisomy 21.

Facial Abnormalities: Intraorbital Distance

• Hypotelorism: decreased intraorbital distance associated with syndromes and holoprosencephaly, possibly severe enough to demonstrate a single fused eye (cyclopia).
• Hypertelorism: increased infraorbital distance associated with anterior cephalocele and other syndromes.
• Measure outer edge to outer edge of the orbit plus the inner edge to inner edge of the orbit.
• Normal distance depends on fetal age.
• Outer orbital diameter (OOD) and inner orbital diameter (IOD) are viewed in sonograms demonstrating the orbits in the coronal view.
• The IOD is measured from the medial border of the orbit to the opposite medial border.
• The OOD is measured from the outermost lateral border of the orbit to the opposite lateral border.

Facial Clefting

• Most common congenital facial abnormality.
• Occurrence statistics include 25% with cleft lip only, 25% with cleft palate only, and 50% with both.
• Diagnosis depends on the identification of a cleft lip.
• Causes are multifactorial and associated with many syndromes.
• Asymmetric facial clefting may occur with amniotic band syndrome.
• Sonographic findings include anechoic cleft extending from nostril to lip; the philtrum should not be mistaken for this.
• It’s usually best demonstrated in a coronal section.
• May be associated with polyhydramnios and difficult to detect isolated cleft palate.
• 3-D imaging can be helpful in evaluating cleft lip.

Median Cleft Lip:

• This is a rare anomaly consisting of a midline vertical cleft through the upper lip, possibly involving the premaxillary bone, nasal septum, and central nervous system.
• May or may not have cleft palate.
• It is related to differentiation of the forebrain and associated with other midline defects like holoprosencephaly.
• Key sonographic finding is similar to cleft lip/palate.
• Search for other facial and intracranial abnormalities.
• Examples diagrams of unilateral, bilateral, and median cleft lip anomalies

Tongue Abnormalities

• Tongue protrusion may suggest macroglossia, found in Beckwith-Wiedemann syndrome.
• Organomegaly also features macroglossia.
• Some glycogen storage diseases may exhibit macroglossia and organomegaly.

Mandible Abnormalities

• Micrognathia: abnormally small jaw associated with chromosomal abnormalities like Trisomy 18.

Other Abnormalites

• Frontal Bossing: prominent forehead due to absent nasal bridge associated with skeletal dysplasia and other syndromes.

Masses of the Face

• Epignathis: a rare pharyngeal teratoma protruding from the fetal mouth, appearing as a complex, cystic and solid mass that may hyperextend the neck.
• It is associated with polyhydramnios due to fetal inability to swallow.
• Proboscis: a rare congenital anomaly of an appendage-like structure projecting from the midline fetal face/forehead, further classified into subtypes based on location (e.g., inter-orbital proboscis).
• The presence of a proboscis can be associated with conditions such as trisomy 13, holoprosencephaly, cebocephaly, ethmocephaly, or cyclopia (often below the level of the proboscis).
• A proboscis is best seen on a longitudinal facial profile view.

Abnormalities of the Neck

• Cystic Hygroma: benign, developmental abnormality of lymphatic system origin with single or multiple cystic areas forming around the neck and associated with chromosomal abnormalities like Turner's and Down Syndrome.
• Large hygromas are often associated with fetal hydrops.
• Sonographic Findings: thin-walled, multiseptated mass at the posterior aspect of the neck, nuchal ligament extending posteriorly, potentially associated with hydrops (fetal ascites, ansarca, pleural effusion) that mimics cervical teratoma, encephalocele, or cervical meningomyelocele
• Cervical Teratoma: complex/cystic/solid mass near the fetal neck that can occur anywhere around the neck, potentially mistaken for a cystic hygroma or pharyngeal teratoma.
• Nuchal Thickening: increased thickness of soft tissue at the posterior aspect of the neck associated with trisomy 21.
• Image the oblique/axial cross section of the head showing the CSP, cerebellum, and cisterna magna.
• A measurement greater than 6 mm between 15 and 21 weeks is considered abnormal.
• Fetal head must not be hyperextended while taking a measurement.

Understand fetal facial feature identification using sonography. Learn about optimal views for detecting cleft lip/palate and orbital abnormalities. Explore anomalies like flattened nose, micrognathia, and the importance of nasal bridge imaging.