Fetal head and neck Midsagittal plane

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The magnified midsagittal plane of the head and neck enables the assessment of many anatomic regions to include NT, facial profile with nasal bone and posterior fossa.

Section Structure

1. NT (Nuchal Translucency)
2. Nasal Bone
3. Maxilla
4. Mandible
5. Thalamus
6. Brain Stem
7. Fourth Ventricle
8. Choroid Plexus
9. Cisterna Magna

Head – Present, cranial bones, midline falx, choroid plexus fill ventricles
Neck – Normal appearance, nuchal translucency thickness (if accepted after informed consent and trained/certified operator available)
Face – Eyes with lens, nasal bone, normal profile/mandible, intact lips
Spine – Vertebrae (longitudinal and axial) intact, overlying skin
Chest – Symmetrical lung fields, no effusions or masses
Heart – Cardiac regular activity, four symmetrical chambers
Abdomen – Stomach present in left upper quadrant, bladder, kidneys
Abdominal Wall – Normal cord insertion, no umbilical defects
Extremities – Four limbs each with three segments, hands and feet with normal orientation
Placenta – Cord size and texture
Cord – Three-vessel cord
Facial Profile – The facial profile is assessed in its entirety to include the forehead, nasal bridge, nasal bone, maxilla, and mandible. Checklist of the anatomic evaluation of the magnified midsagittal plane of the fetal face. Abnormalities that can be detected in this plane include…

1. Anencephaly
2. Holoprosencephaly
3. Anterior Cephalocele
4. Proboscis
5. Absent Nasal Bone
6. Maxillary Gap or Protrusion (Associated with Cleft Palate)
7. Epignathus
8. Retrognathia
9. Others

Forehead – Normal shape; not too flat, no excessive bossing, no structure protruding
Nasal Region – Nose present and nasal bone ossified
Maxilla – No maxillary gap, no protrusion
Mouth – Upper and lower lips appear normal
Mandible – Normal appearance, no retrognathia
Posterior Fossa – In the midsagittal plane, the anatomy of the posterior fossa can be thoroughly examined and includes the following landmarks: hypoechoic brainstem with echogenic posterior border, anechoic fourth ventricle (intracranial translucency), posterior echogenic choroid plexus of the fourth ventricle, and the anechoic cisterna magna, located posterior to the fourth ventricle and anterior to the echogenic occipital bone. Checklist of the anatomic evaluation of the midsagittal plane of the posterior fossa. Abnormalities that can be detected in this plane include…

1. Open spina bifida with thickened brainstem and reduced fluid
2. Increased fluid in the fourth ventricle seen in aneuploidies
3. Blake’s pouch cyst
4. Dandy–Walker malformation
5. Posterior cephaloceles and other

Thalamus – Visualized as midline structure
Brainstem – Visualized with posterior echogenic border; normal shape, not thickened, not kinked, and not thin
Intracranial Translucency (Fourth Ventricle) – Typical fluid space and echogenic lines; choroid plexus of fourth ventricle and cisterna magna visualized