The document provides details about performing and interpreting a fetal anatomy scan between 18-20 weeks of gestation. It describes assessing various fetal anatomical structures including the brain, skull, abdomen, lungs, heart, spine, and limbs. Key measurements and normal ranges are outlined. Common congenital anomalies that may be detected on the scan are also described for various structures. The purpose of the anatomy scan is to evaluate fetal anatomy and screen for potential fetal anomalies.

1. DR SOUMITRA HALDER
JUNIOR RESIDENT
DEPT. OF RADIO-DIAGNOSIS
MEDICAL COLLEGE, KOLKATA

2.  Period.. 13w od to 27w 6d
 Majority between 18-20 w
 Routinely performed on all preg women
 Emphasizes on fetal anatomy so named …
Fetal Anomaly Scan
2nd
Trimester Anatomy Scan
 TIFFA (Targeted Imaging For Fetal Anomalies)TIFFA (Targeted Imaging For Fetal Anomalies)
ScanScan

3.  Fetal number
 Viability
 Presentation
 Fetal biometry
 Fetal Anatomic screening
 Amnionitic fluid
 Placenta
 Cervix
COMPONENTS

4. Fetal Biometry….
BPD TCD
HC NFT
AC NBT
FL CM
HL

5. BPD
 Correct levels
 Measured at a focus which shows, both the THALAMITHALAMI &
the CAVUM SEPTUM PELLUCIDUMCAVUM SEPTUM PELLUCIDUM..

6. SutureSuture

8. CSPCSPThalamusThalamus
Lateral LobeLateral Lobe
VermisVermis
CisternaCisterna
MagnaMagna
Choroid PlexusChoroid Plexus

9. MeasurementMeasurement
The outer table of the skull on the superior end of the image upto theThe outer table of the skull on the superior end of the image upto the
inner table of the skull at the inferior end of the imageinner table of the skull at the inferior end of the image
BPD

10. Not useful when the head shape is abnormal i.e, elongated or excessively roundNot useful when the head shape is abnormal i.e, elongated or excessively round
..
BPD is commonly affected by fetal position. Eg. Breech presentationBPD is commonly affected by fetal position. Eg. Breech presentation
Better to use the parameter ofBetter to use the parameter of CEPHALIC INDEX (CI)CEPHALIC INDEX (CI), instead of BPD alone., instead of BPD alone.
Also, the CI remains constant during the 3Also, the CI remains constant during the 3rdrd
trimester.trimester.
Cephalic Index (CI) = BPD / OFD X 100Cephalic Index (CI) = BPD / OFD X 100

11. OFD

12. H C
 Same view as BPD
 Outer to outer

13. A C
Landmark features:
 Circular section with ribs
 One vertebra -triangle of 3 white
spots
 Umbilical vein - hockey stick
 Stomach

14. A C

15. F L

16. TCD
 Measured from the outerMeasured from the outer
to outerto outer

19. Placenta

20. PLACENTAL LOCALISATIONPLACENTAL LOCALISATION

21. MARGINALMARGINAL
PLACENTA PRAEVIAPLACENTA PRAEVIA

22. COMPLETE PLACENTACOMPLETE PLACENTA
PRAEVIAPRAEVIA

24. PSEUDO- PLACENTA PREVIAPSEUDO- PLACENTA PREVIA

26. Measured by adding the values of individual amniotic pocket depths (in cm's) forMeasured by adding the values of individual amniotic pocket depths (in cm's) for
each of the four quadrantseach of the four quadrants
Pocket chosen is free from the cord or any fetal part or placental tissue.Pocket chosen is free from the cord or any fetal part or placental tissue.
The normal range for amniotic fluid volumes varies with gestational age.The normal range for amniotic fluid volumes varies with gestational age.
AFI of < 5 OligohydramniosAFI of < 5 Oligohydramnios
5 - 25cm NORMAL5 - 25cm NORMAL
AFI of > 25 PolyhydramniosAFI of > 25 Polyhydramnios

27. MAXIMAL VERTICAL POCKETMAXIMAL VERTICAL POCKET
<< 2 cm : Oligohydramnios 2 cm : Oligohydramnios
> 8 cm : Polyhydramnios> 8 cm : Polyhydramnios
2-8 Cm Normal

28. fetal anatomy assessment
Its imp to go through all-complete coverage--> then
no major abnormalities will be missed

29. Head & Brain
Cranial structures to Note at routine anat. Scan
1.Head shape
2.Ventricle
3.CSP
4.Thalamus
5.Cist Magna
6.Nuchal fold
7.cerebellum

30. DOLICOCEPHALYDOLICOCEPHALY BRACHYCEPHALYBRACHYCEPHALY
CLOVER LEAF SKULLCLOVER LEAF SKULL

31. ANENCEPHALYANENCEPHALY
 No skull vault / cranium is seen.No skull vault / cranium is seen.
 Brain tissue absentBrain tissue absent
ACRANIAACRANIA
 Cranium is absentCranium is absent
 Major part of the brain tissue mayMajor part of the brain tissue may
present .present .
Replaced by flattend amorphous massReplaced by flattend amorphous mass
(EXENCEPHALY)(EXENCEPHALY)

32. AnencephalyAnencephaly
(Frog Eye(Frog Eye
SignSign))
AcraniaAcrania
(absent Cranium(absent Cranium
But Brain tissue present)But Brain tissue present)

33. MENINgoCELEMENINgoCELE
When it contains only meningesWhen it contains only meninges
MENINgoENCEPHALoCELEMENINgoENCEPHALoCELE
Brain tissue is included in theBrain tissue is included in the
herniated tissue.herniated tissue.
CEPHALoCELE
Intracranial tissue herniates
Through a defect in cranium

34.  May be seen as a purely cysticMay be seen as a purely cystic
mass or may contain echoes frommass or may contain echoes from
herniated brain tissue.herniated brain tissue.
 If the mass appears cystic, theIf the mass appears cystic, the
Meningoecele componentMeningoecele component
predominatespredominates, while a solid masssolid mass
indicates predominantly anindicates predominantly an
EncephaloceleEncephalocele.
 Larger encephalocoeles may showLarger encephalocoeles may show
accompanying microcephaly.accompanying microcephaly.

35. VENTRICULOMEGALY
Ventricular size measurements…
1.Atrial width
2.V/H ratio
3.Choroid separation
4.Comb ant horn width

36. Atrial Width
 Most useful and accepted
 Must be taken on true axial view
 Measured at widest part of ventricles
 Inner to inner vent walls
10-12 borderline
12-15 moderate
>15 severe

37. Dangling Choroid

38.  May be Unilateral orMay be Unilateral or
Bilateral.Bilateral.
 Usually transient & benign.Usually transient & benign.
 Seen in fetus normallySeen in fetus normally
between 16 – 21 weeks, afterbetween 16 – 21 weeks, after
which they start regressingwhich they start regressing..

39. HOLOPROCENCEPHALY
 Resulting from incomplete separation of theResulting from incomplete separation of the
two hemisherestwo hemisheres
 3 types… ALOBAR3 types… ALOBAR
SEMILOBARSEMILOBAR
LOBARLOBAR

40.  No inerhemisheric division..they
are fused
 Absent Corpus Callosum
 Single ventricle….Horse-shoe
 Thalami fused
 Absent olfac tract
ALOBA
R

41. SEMILOBAR
 Incomp interhemsph division…
Fused ant.
 Rudimentary cerbral lobes
 Partial/complele Fusion of Thallamus

42.  Interhemis division fullyInterhemis division fully
formedformed
 Fusion of Frontal horns ofFusion of Frontal horns of
lateral ventricles.lateral ventricles.
 Midline cont. fronal neocortexMidline cont. fronal neocortex
 Septum pellucidum is absentSeptum pellucidum is absent
 Thalami are separateThalami are separate
 Fully devolop cerebral lobesFully devolop cerebral lobes
LOBAR

43. Syntelencephaly
 Middle interhemisheric form of holoprocencephaly

44. DANDY-WALKER MALFORMATION
1. Cystic dilatation of 4th
vent.
Communicating with post fossa
2. Enlarged post fossa
3. Elevated Tentorium
4. Hypoplastic or absent vermis

45. Dandy-Walker Variant
 Less severe form of classic DWM
 Partial Hypoplasia of vermis
 Partial 4th
vent obstruction
 Not much enlargement of post fossa

46. FETALFETAL
ABDOMENABDOMEN
scanscan

47.  Physiological Emptying : TransientPhysiological Emptying : Transient
 Lack Of Amnionitc Fluid ToLack Of Amnionitc Fluid To
SwallowSwallow
Oligohydramnios Oligohydramnios
Anhydramnios Anhydramnios
 Impaired Fetal SwallowingImpaired Fetal Swallowing
 Esophageal AtresiaEsophageal Atresia
 Obstructing Oropharyngeal Mass Obstructing Oropharyngeal Mass
Cervical TeratomaCervical Teratoma
 Facial CleftsFacial Clefts
 CongenitalCongenital
DiaphragmaticDiaphragmatic
HerniationHerniation ::
fetal stomach may be absentfetal stomach may be absent
in an axial ultrasound scan –in an axial ultrasound scan –
standard view due tostandard view due to
migration into the thoraxmigration into the thorax
Absent stomach bubble

48. Esophageal AtresiaEsophageal Atresia

49.  2nd
bubble equal or smaller than stomach bubble
 Shows communication with stomach
D/D…Duodenal atresia
Choledochal cyct
Duplication cyst
Double bubble sign
 Another bubble adjacent to stomach bubble
Other than GB
D.atresia

51. Look for ant abd wall with cord insertion…
 Para-umbilical abdominalPara-umbilical abdominal
wall defectwall defect..
Herniation fetal bowel loopsHerniation fetal bowel loops
occasionally portions oroccasionally portions or
the stomach and or liver intothe stomach and or liver into
amniotic cavityamniotic cavity
GASTROSCHISIS
Free floating
Not Covered
GASTROSCHISIS

52.  Midline abdominal wall defectsMidline abdominal wall defects
 Herniation of intra abd contentsHerniation of intra abd contents
into base of cordinto base of cord
OMPHALOCELE

53. Gross ascites
Skin oedema
Fetal Hydrops

54. Dilated Bowel
>7 mm in small bowel
>20 mm in large bowel
Obstruction

55. High Echogenic Bowel
Chromosomal
abn

56.  Fetal kidney seen from 14 wks
 Can be identified through renal art
 Renal agenesis..renal artery are also absent
 B/L Ren agenesis associated with oligo /anhydramnios
 Measurement of Renal pelvis AP diam
 inner to inner aspect of pelvis
 upper limit 4-5 mm in 2nd
trimester
 Look for Renal cystic ds
UROGENITAL SYSTEM

57.  Fetal bladder visible after 12 wk
Over distended bladder
B/L Hydro-urtero nephrosis
Obstructive uropathy

58. DR SOUMITRA HALDER
JUNIOR RESIDENT
DEPT. OF RADIO-DIAGNOSIS
MEDICAL COLLEGE, KOLKATA
PART - II

60. Important Viwes
Saggital profile view
Axial view Orbit
Axial View Maxilla/Mandible
Nose-Lip view

66. ABNOMALITES….

67. Retrognathia

68. mm=Ges age

69. Frontal Bossing

70. Slopped Forehead

71. Agnothia

72. ORBIT
 Should be symmetrical size
 Inner & outer distance in normal range
 Round shape

74. Hypotelorism

75. Proboscis
Cyclopia

76. Hypertelorism

77. Micropthalmia

78. Anopthalmia

79. Dacrocystocele

80. Absent Nasal bone

81. PT/NBL ratio
NBL= Nasal Bone Length
PT= Prenasal thickness
N=0.35-0.8
CHR ABN= > 0.8

82. Cleft lip

83. Macroglossia

86. Lung:
Homogenous
echogenic tissue
Separated by
hypoechoic
domeshaped
diaphragm

88. Hypoechogenic structure
other than heart….

89. CCAM

90. Pul Hypo

91. CDH

92. Pl effusion

93.  Occupy 1/3 – ½ of thorax
 Cardiac position & situs is
Imp
 Apex points toward Lt
 Lt atr close to spine
 Rt Vent close to chest wall
HEART

94.  2 ventricles/ walls of equal size
 2 atria / walls of equal size
 Foramen ovale moving in left atrium
 Pulmonary veins entering left atrium
 Motion of mitral valves (left side) regular
 Motion of tricuspid valves (right side) regular
 Continuity of interventri septum
Check at a Glance

95. The ultrasound beam is directed
perpendicular to the midchest
plane at the level of the heart.
 These chambers consist of the
right and left atrial and both
ventricular chambers
Corresponding valves between
them
Four-Chamber View

96. Four-Chamber View

97. v
On Slight angulation

98. Towards rt shlder

99. Short-axis
view
Grt Vs
Toward Lt shoulder

100. Apical 5
chamber
view
Cephalad direction

101. 3 Vs &
Trachea
view

102. Aortic arch

103. Ductus
arch

104. ASD

105. VSD

106. Hypo Rt Vent

107. TOF

108. TA

109. Double Outlet RV

110. TGA

111. Rhabdomyoma

112. Echogenic
intracardiac focus

113. SPINE

114.  Coronal or Sagital of entire spine:
 cervical
 Thoracic
 Lumbar
 Sacral
 Transverse assessment of entire spine: Triangular 3
dots form closed triangle

116. Spina Bifida

117. Spina
bifida
w
ith
m
eningom
ylocele

118. Overlying skin at
Sacrum is absent

119. Caudal
regression

120. Teratoma

121. LIMB
S Confirm the 3 long bones
 Presence of Foot & Hand
 Complete Absent....Amelia
 Look for Phacomelia
Phacomelia

122. Bone scanned throughout long section
Look for any bowing ,angulation ,#
Club foot
No of fingers

125. Extremety measurements
 FL routinely
 All bones in background of family history
& strong suspicion

126.  Clavice lengh in mm = Gest age in wk

127. Protocol
<2 SD
F/U scan after 3-4 wks
<4 SD
Sk dys
Further <1 SD
Sk dys

128. Pattern of limb shorting
Rhizomelia.. …….Prox
Meso… ………….Middle
Acro…. …………..Distal
Micro……………..Entire limb

129. Femur /Foot Length ratio
N =1.
Constitutionaly small/IUGR= > 0.9
Sk dys < 0.9