Fetal Head anatomy

Characteristics of normal fetal head
Oval
highly echogenic
axial sections obtained at multiple levels

Measurements taken of the fetal head
BPD, HC, Lateral ventricles, Cerebellum, Cisterna Magna and nuchal thickness

First level of Intra cranial anatomy
lateral ventricles

Ventricles of the brain are
part of a system which helps manufacture and distribute cerebral spinal fluid made up of clear fluid that baths entire CNC

Cerevralspinal fluid is produced by
the choroid plexus

Functions of Cerebralspinal fluid
Pritection, Excretion of waste and an endocrine medium for the brain

The lateral ventricles are also known as the
first and second ventricles

regions of the lateral ventricles
frontal horns
occipital horns
temporal horns
atria

The frontal horns
Most anterior region

the occipital horns
Most Posterior region

The temporal horns
inferior, most lateral

the atria
junction of the temporal and occipital horns

Measurement of the lateral ventricle sonographically
widest diameter should not exceed 10mm at all times during pregnancy

Widest diameter of the atria is
measured through the choroid plexus

The choroid plexus is
predominent echogenic areas within the lateral ventricles

Interconnected series of hollow spaces in the fetal brain are called
ventricles filled with cerebral spinal fluid

The ventricular system consists of 4 ventricles that are
connected by tiny ducts

CSF flows from lateral ventricles through
foramen of monro

the third and fourth ventricles are connected to each other via
aqueduct of sylvius

The fourth ventricle is connected to the central canal of the spinal cord laterally by
foramina of luschka and medially by a single foramen of magendie

all ventricles are connected with one another and
the subarachnoid space and spinal canal

Choroid plexus cysts
the most common intracranial findings

Most choroid plexus cysts are normal but can also be associated with
trisomy 18

Choriod plexus cysts are composed of
cerebrospinal fluid and cellular debris which become trapped within neuroepithelial folds

Choriod plexus cysts are observed prenatally from
15-24 weeks of pregnancy

Choroid plexus cysts should reside by week
24

Fetuses with bilateral or large choroid plexus cysts may be recommended for
amniocentesis

Hydrocephalous
Dilation of the ventricular system secondary to an increase in the CSF volume
Lateral ventricles exceed 10mm

effects of hydrocephalous
flattening of parenchyma which causes demylenation and brain damage

Hydrocephalous is found with
any stenosis of the CSF pathway

2 classifications of hydrocephalous
Obstructive, non communicating and communication

Obstructive or non communicating hydrocephalous
Aqueductal stenosis, CNS anonoly or tumors. examples are spin bifida or choroid plexus papiloma

Communicating hydrocephalous
faulty absorption or increased CSF production

Most common stenosis in hydropcephalous
stenosis of the aqueduct of sylvius

Level 2 of brain
BPD mis brain level and level of ears

BPD measurement
axial measurement between thalami, flax and CSP
Outer to inner measurement

Falx cerebri
separates the hemispheres

Thalami
2 hypoechpoiec structures that appear oval

the between the thalami lies
the third ventricle that appears anechoic, linear slit and is a passageway for CSF throughout brain

cavum septum pellucidum
anterior to the thalami, white matter outlined by 2 short bright echogenic lines

third level
cerebellum, cisterna magna and nuchal fold
all in one image

third level fetal brain measurement is used for
gestational dating and measured between 14030 weeks

Cerebellum
located in the posterior fossa, appears as two rounded structures and joined in center by cerebellar vermis. abnormal size indicates abnormality

cisterna magna
aka posterior fossa, directly behind cerebellum
normal measurement is 3mm-10mm

normal measurement of the cistern fossa excludes
spinalbifiba or obstruction

Spinal bifida
decreases fluid in the cistern magna

nuchal fold
the skin behind the occipital bone

normal measurement of the nuchal fold
6.0 mm after 16 weeks

If the nuchal fold is greater than 6mm indicates
down syndrome

the nuchal fold is measured by
the calipers outer skull to outer skin surface

Dolicicephaly
elongated front to back and narrow on sides

dolcicocephaly is associated with
decreased amniotic fluid

brachycephaly
shortened front to back and triangular

brachycephaly is associated with
congenital, chromosomal and skeletal abnormalities

lemon shaped
bifrontal indentation, high association with spinalbifida

clover leaf
premature closing of coronal and lambed sutures causing temporal bones to bulge out
Fatal

Micropcephaly
small head, caused by infection exposure, alcohol drugs and toxins while pregnant and malnutrition of mother. can cause seizures and developmentally delayed

macrocephaly
enlarged ventricular system, hydrocephalous

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