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1. FETAL ANOMALIES BY
PGR-II RADIOLOGY DEPARTMENT
MAYO HOSPITAL LAHORE.
2. NORMAL USG ANATOMY OF FETAL HEAD
3. Basic axial planes 1. Transthalamic view
CSP, 3rd ventricle, thalamus
malformation of midline development
2. Transventricular view
ventricular atrium, cbr.hemisphere
3. Transcerebellar view
cbll, cbll vermis, cisterna magna, 4th ventricle
DW malformation, myelomeningocele
8. FETAL ANOMALIES Incidence of major cong. Anomalies (CFA):
2.5% of total births (1/3 neural tube & conge.Ht1/3).
CNS abnormality constitute the majority
spina bifida 1:1000
9. Causes of Congenital Fetal Anomalies Single gene disorders 20%
10. CNS ABNORMALITIES
11. Anencephaly Defined Absence of brain tissue and skull bones.
Folic Acid Deficiency
As ossification of the fetal skull is normally completed by 11 weeks, the diagnosis of absence of the
cranium or anencephaly can be made reliably
After this gestation.
12. Anencephaly is a progreesive procedure initially
In first trimester there is
Absence of cranial vault (Acrania).with
uncoverd brain tissue (exencephaly)
Erosion of exposed brain tissue
Classsic Frog,s eye appearance
in which the fetal skull ends just above the orbits
13. Anencephaly In Ist trimester in 2nd trimester
15. Anencephaly (cont.) On Ultrasound
Anencephaly can be missed in first trimester because the brain can appear normal and the absence of the skull bones (i.e. acrania)is overlooked.
If In the second or third trimester the fetal head
cannot be visualized It is assumed to
be deep in the maternal pelvis,or deep to ribs in
case of breech
16. Associated Symptoms
None, incompatible with life Anencephaly (cont.)
17. Amnionic Fluid Volume It can be accurately diagnosed as mild ,
modereate and severe by the subjective
-Amniotic fluid index it is a more sensitive
indicator of AFV throughout pregnancy.
It is a total of the Deepest Vertical Pocket in each four quadrants of the uterus..
18. Amniotic fluid abnormalities Oligohydramnios:
Defined as reduced amniotic fluid
Maximal vertical fluid pocket : < 2cm
amnionic fluid index : < 6cm
Defined as excessive amount of amniotic fluid
Maximal vertical fluid pocket :>8 cm
Amnionic fluid index :>24cm
19. Causes of oligohydramnios: 1. Fetal causes:
*Renal cause (57%):
- polycystic kidney.
- Urethral obstruction (atresia/posterior urethral valve).
* Fetal growth restriction.
* Fetal death.
* Postterm pregnancy.
* Preterm premature rupture membranes
20. Causes of oligohydramnios: 2. Maternal causes:
3. Placental causes:
4. Drug causes:
Prostaglandin synthase inhibitor as NSAID.
21. Polyhydramnios GRADES
1. Mild hydramnios :
a pocket of amniotic fluid measuring 8 to 11 cm.
2. moderate hydramnios :
a pocket of amniotic fluid measuring 12 to 15 cm.
3. Severe hydramnios - twin-twin transfusion syndrome :
a pocket of amniotic fluid measuring 16 cm or more.
22. Causes of polyhydramnios Fetal malformation: 20%
- GIT:Faliure of swallowing or absorption ( esophageal/duodenal atresia,
- CNS: anencephaly
Twin-twin transfusion ? fetal polyuria.
Hydrops fetalis(10) congestive heart failure, severe anaemia or hypoproteinemia
diabetes mellitus (osmotic diuresis). 25%
25. Ventricular System Four interconnected cavities
House choroid plexus
Secretes cerebrospinal fluid
Right and left lateral ventricles
Foramen of Monro connects lateral ventricles to:
Connected to fourth ventricle by:
27. CSF FORMATION CSF secretion is an active process.
70% by ventricular choroid plexuses,
30% by extrachoroid sources
metabolic water production
rate of production is 0.35 ml/min or 500 ml/day.
28. CSF is passively absorbed by:
Arachnoid villi into venous dural sinuses
other pathways of absorption:
spine venous plexuses.
perivascular and the perineural sheaths.
29. Assessment of ventriculomegally Measurement of lateral ventricle
At the the level of atrium of lateral ventricle which is junction of boby and occipital horn.coroid plexus lies just anterior to it
Atrium with coroid plexus is best viualized in axial image superior to the level of
32. Why at Atrium
Atrium is the most sensitive
to the development of early hydrocephalus
LV which is farther from
the transducer is easy to
33. HOW TO measure Atrium of LV is measured perpendicular to its walls
Upper limit is 10mm
10 to 15mm mild ventriculomegally
34. Measurement of ventricles(cont.) Dangling Coroid plexus sign
Normally 60 to 90% of width of atria is occupied by
In case of ventriculomegally its size decreases relative
35. Dangling Coroid plexus sign
36. Dilated 3rd ventricle
Would be rounded
oval or triangular.
Exceeds 3mm in dia
37. Ventriculomegally Hydrocephalls
DILATED VENTRICLES are DUE To
Enlargement of ventricles due to EX VACUO phenomenon in which ventricles expand to full fill the spaces created by destruction of the brain parenchyma in the frontal temporal and parietal region
Due to thrombosis of both middle cerebral arteries
In utero infection
38. USG DIFFERENCES Hydrocephalls
Regardless of severity there is
always a Rim of of brain parenchyma
Rim of of brain parenchyma
occasionally present but mostly abscent
39. USG DIFFERENCES(cont.) Hydrocephalls
Disturbed Falx mid line
echo in severe cases
Intact falx midline echo
DIVERSE GROUP OF CONDITIONS IN WHICH THERE IS IMPAIRED CIRCULATION AND RESORPTION OF CSF RESULTING INTO
INCRESED INTRAVENRICULAR PRESSURE
42. TYPES OF HYDROCEPHALUS OBSTRUCTIVE OR NON-COMMUNICATING (OBSTRUCTION WITHIN THE VENTRICULAR SYSTEM)
NON OBSTRUCTIVE OR COMMUNICATING (MALFUNCTION OF ARACHNOID VILLI)
43. HOW TO ASSESS LEVEL OF OBSTRUCTION RULE OF THUMB.
The level of obstruction can not be higher
then the lowest dilated part of ventricular
44. HOW TO ASSESS LEVEL OF OBSTRUCTION Only LV dilated(rare)
Obtruction of foramen of
If lateral and 3rd ventricle dilated
Obstruction level is
aqueduct of sylvius
45. IF lateral,3rd and 4th ventricles dilated
Most likely Communicating hydrocephalus
46. CAUSES OF HYDROCEPHALUS LESIONS OR MALFORMATIONS OF
THE POSTERIOR FOSSA
CHIARI MALFORMATION type II
DANDY- WALKER SYNDROME
ASSOCIATED WITH SPINA BIFIDA
47. Treatment Surgical
Removal of obstruction
Placement of shunt
VP shunt (ventriculoperitoneal shunt)
48. VP Shunt
52. Cephalocele Protrusion of intracranial structures through
the calvarial defect.
Defect is usually in the occiput (although it
can be in the frontal, nasal or parietal bones)
53. Encephalocele Protruded sac contains meninges as well as parts of the brain
prognosis is poor
Herniation of meninges alone , through calvarial defect
54. Encephalocele Protrusion of intracranial contents through a cranial defects
Ranges from size of small bubble to entire brain located out side the collapsed calvarium
Can be associated with multicystic kidneys
(Potter?s type III renal dysplasia) and polydactyly;
condition known as Meckel?Gruber syndrome
DDx :cystic hygroma- haemangioma- teratoma.
56. Choroid plexus cyst Incidence : 1% in second trimester
Majority : isolated & resolve by 24 weeks
It may be associated with
Trisomy 18(EDWARDS SYNDROME)
club feet or rocker bottom defect
clenched hands and overlaping digits
Neural tube defects
Two vessels umbilical cord
59. Holoprosencepahly Failure of normal forebrain development or incomplete division
alobar, semilobar, lobar
US of alobar/semilobar type
Fusion of thalamus
Absence of midline structure
: corpus callosum, fornix, optic tract,
61. Agenesis of corpus callosum The corpus callosum is a bundle of nerve
fiber that lies immediately caudal to the
cavum septumpellucidum and connects the two cerebral hemispheres.
62. Agenesis of corpus callosum USG Findings can not be detected easily on usg,however it is strongly suspected if there is Absence of cavum septum pellucidum
tear drop sign _due to dilated anterior horn
Dilated occipital horn
upward displacement of 3rd ventricle
absence of corpus callosum
May be incidental finding without any clinical significance
64. POSTERIOR FOSSA AND NUCHAL SKIN It is well seen in
axial view at the level
of thalami or midbrain
Bilobed cerebellum is identified
as hypoechioc lateral
hemispheres ,and midline
65. Cisterna megna is noted between the
cerebellum and occiput.
Measured from posterior border of vermis to inside
of occipital bone
Normal range between 2-10 mm
66. POSTERIOR FOSSA Abnormalities
Cisrterna megma is markedly enlarged and cerebeller hemispheres are splayed apart
67. Dandy-Walker malformation
Complete/partial agenesis of cbll vermis
So posterior fossa cyst communicates with 4th ventricle
& elevated tentorium
Frequently associated with other fetal anomalies
Variable hypoplasia of cbll vermis
Findings are similar but less severe
68. Dandy-Walker malformation
69. Chiari II
? Cerebellar Herniation into cervical canal through
Foramenmagnum plus Medullary distortion and dysplasia
CISTERNA MAGNA is obliterated
HYDROCEPHALUS in 90%
Myelomeningocele in 100%
Syringohydromyelia in 50%-90%
70. Chiari II: Brain MRI
72. Chiari I ANATOMY
Peglike cerebellar tonsils displaced into
upper cervical canal ( >10mm)
Skeletal anomalies 25%
73. nuchal fold thickness Nucal fold refers to the layer of soft tissue identified immediately posterior to the occipital bone.
Nuchal fold thickness : > 6mm, at 15~20 wks
Most sensitive & specific single marker for 1st & midtrimester detection of Down?s syndrome
75. Nuchal Translucency (NT)
76. Nuchal translucency (NT) What is it?
Measurement of the hypoechoic area (fluid) that collects behind the fetus? neck
Measured by ultrasound between 10 and 14 weeks? gestation
Why is it important?
Indication of fetal distress/abnormalities like Down?s syndrome
Trisomy 21, Trisomy 18, heart defects
78. Spine 15-16 weeks: seen well
3 ossification center : centrum & lamina
Showing oval/triangular lumen
lamina : parallel or
79. Spina Bifida
Failure of the spine to close properly during the first month of
2nd most common ONTD
Results in to Meningocele
Associated anomalies (hydrocephalus-encephalocele).
85. MYELOMENINGOCELE Herniation of malformed cord + meninges through vertebral defect due to Failure of complete closure of caudal neural tube
Usually associated with Arnold-Chiari and hydrocephalus
Lumbosacral level most
92. Cystic hygroma Cong. malformation of the lymphatic system
Location : posterolat. aspect of neck
Ass. anomalies : Turner syndrome
thin walled, multiseptated cystic mass
Ass. hydrops fetalis
95. Porencephalic cyst A porencephalic cyst is a cyst found in the cerebral hemisphere and is the result of
liquefaction of an intracranial hemorrhage.
cause is hypoxic rupture of the small vessels
They are distinguishable from choroid plexus cysts because they are extraventricular
usually single and unilateral.
96. Longitudinal section of the lower spine
showing agenesis of the lumbar vertebrae and sacrum
97. Sacral agenesis (caudal regressionsyndrome It ranges in severity from absence of the sacrum
with short femora to complete fusion of the lower
Rare abnormality that is seen
almost in infants born to mothers with
insulin-dependent diabetes mellitus
98. From 1 April 2010