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FETAL ANOMALIES






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NORMAL USG ANATOMY OF FETAL HEAD. Basic axial planes. 1. Transthalamic view CSP, 3rd ventricle, thalamus malformation of midline development2. Transventricular view ventricular atrium, cbr.hemisphere ventriculomegaly3. Transcerebellar view cbll
FETAL ANOMALIES

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1. FETAL ANOMALIES BY DR.KHALID IDREES 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 ventriculomegaly 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 including anencephaly 1:1000 spina bifida 1:1000 cephalocele 1:4000

9. Causes of Congenital Fetal Anomalies Single gene disorders 20% Chromosomal 5% Environmental 10% Drugs 3% Infections 3% Irradiation 1% Others 3% Multifactorial 65%

10. CNS ABNORMALITIES

11. Anencephaly Defined Absence of brain tissue and skull bones. Causes Taratogens 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 Polyhydramnios Treatment None, incompatible with life Anencephaly (cont.)

17. Amnionic Fluid Volume It can be accurately diagnosed as mild , modereate and severe by the subjective observation -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 Polyhydramnios: 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%): -Renal agenesis (Potter?s syndrome). - 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: Uteroplacental insufficiency. Preeclampsia. 3. Placental causes: twin-twin transfusion. 4. Drug causes: Prostaglandin synthase inhibitor as NSAID. 5. Idiopathic

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, tracheoesophageal fistula). - CNS: anencephaly Twin-twin transfusion ? fetal polyuria. Hydrops fetalis(10) congestive heart failure, severe anaemia or hypoproteinemia Maternal Causes diabetes mellitus (osmotic diuresis). 25% Multiple gestations Idiopathic. 33%

24. VENTRICULOMEGALLY (Hydrocephalus&Hydrenencephaly )

25. Ventricular System Four interconnected cavities House choroid plexus Secretes cerebrospinal fluid Right and left lateral ventricles Foramen of Monro connects lateral ventricles to: Third ventricle Connected to fourth ventricle by: Aqueduct ofSylvius

27. CSF FORMATION CSF secretion is an active process. 70% by ventricular choroid plexuses, 30% by extrachoroid sources capillary ultra?ltrate, ependyma, 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 Site 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 thalamus

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 identify

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 coroid plexus In case of ventriculomegally its size decreases relative to atria.

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 INCRESED INTRAVENRICULAR PRESSURE Hydrenencephaly 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 Pathophysiology 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 Hydrenencephaly Rim of of brain parenchyma occasionally present but mostly abscent

39. USG DIFFERENCES(cont.) Hydrocephalls Disturbed Falx mid line echo in severe cases Hydrenencephaly Intact falx midline echo

41. DEFINITION: DIVERSE GROUP OF CONDITIONS IN WHICH THERE IS IMPAIRED CIRCULATION AND RESORPTION OF CSF RESULTING INTO INCRESED INTRAVENRICULAR PRESSURE AND VENTRICULOMEGALLY

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 system

44. HOW TO ASSESS LEVEL OF OBSTRUCTION Only LV dilated(rare) Obtruction of foramen of monro 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 TUMORS INTRAUTERINE INFECTIONS ASSOCIATED WITH SPINA BIFIDA

47. Treatment Surgical Removal of obstruction tumor Placement of shunt VP shunt (ventriculoperitoneal shunt)

48. VP Shunt

51. Cephalocele

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 Cranial Meningocele 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) Heart defects club feet or rocker bottom defect clenched hands and overlaping digits facial clefts Neural tube defects Two vessels umbilical cord

57. ???

59. Holoprosencepahly Failure of normal forebrain development or incomplete division Classification alobar, semilobar, lobar US of alobar/semilobar type Absent falx Single ventricle Fusion of thalamus Absence of midline structure : corpus callosum, fornix, optic tract, olfactory bulb

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 CEREBELLUM Bilobed cerebellum is identified as hypoechioc lateral hemispheres ,and midline hyperechoic vermis

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 Dandy-Walker complex 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 Dandy-Walker variant 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 Fenestrated falx 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) Syringomyelia 60% 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 Normal <3mm 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 transverse plane lamina : parallel or inwards angulation

79. Spina Bifida Failure of the spine to close properly during the first month of pregnancy 2nd most common ONTD Results in to Meningocele &MYELOMENINGOCELE Associated anomalies (hydrocephalus-encephalocele).

83. Meningocele Spina Bifida

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 Commonly involved(85%)

92. Cystic hygroma Cong. malformation of the lymphatic system Location : posterolat. aspect of neck Ass. anomalies : Turner syndrome US thin walled, multiseptated cystic mass Ass. hydrops fetalis

94. ??

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 regression syndrome It ranges in severity from absence of the sacrum with short femora to complete fusion of the lower limbs ? Rare abnormality that is seen almost in infants born to mothers with insulin-dependent diabetes mellitus

98. From 1 April 2010


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