1. Moderator-
DR. M.C. BANSAL
Professor
DEPTT. OF OBS & GYN
NIMS MEDICAL COLLEGE & HOSPITAL
DR. RIDHI KATHURIA
PG 2ND year
DEPTT OF OBS & GYN
NIMS MEDICAL COLLEGE & HOSPITAL
JAIPUR

3.  Obstetric ultrasound examination at any stage in pregnancy serves two
important functions: Diagnostic and Screening.
 While many major fetal defects can be diagnosed in the first trimester,
the diagnostic accuracy of an ultrasound scan is significantly greater in the
mid-second trimester due to the larger size and more advanced
development of the fetus

4. HCG Levels for normal Pregnancy.
NOTE: The quantitative maternal serum
beta HCG peaks at approximately 10 weeks
and then reduces.
Initial confirmation
of pregnancy is done
by a Urine for
Pregnancy Test kit.
The kit detects hCG
beta subunit in urine
in concentration as
low as 25 mIU/ml.

7. The First Trimester is defined as the first 12 weeks of
pregnancy following the last normal menstrual period
(some authors refer to early pregnancy as 0 - 10 weeks).
It can be divided into a number of phases, each of which
has typical clinical issues. These phases are:
Conceptus phase : 3 - 5 weeks
Embryonic phase : 6 - 9 weeks
Fetal phase : 10 - 12 weeks

8. Ultrasound during this period is predominantly concerned with the following clinical issues:
1. Dating of the pregnancy
MSD : mean sac diameter
CRL : crown rump length (most accurate)
2. Early pregnancy failure
Threatened abortion
Missed abortion
Inevitable abortion
Incomplete abortion
Complete abortion
An-embryonic pregnancy / Blighted Ovum
3. Confirming intrauterine pregnancy (IUP)
Double Decidual Sac Sign
Intradecidual Sign
Double Bleb Sign
4. Ectopic pregnancy
5. Nuchal lucency

9. • GS is the earliest sonographic finding in pregnancy.
• It will be difficult to see if the mother has a
retroverted uterus or fibroids.
• The GS is an echogenic ring (formed by
chorio-emryonic cells) surrounding an
anechoic centre (as fluid filled).
• An ectopic pregnancy will appear the same but it
will not be within the endometrial cavity.
• The GS is not identifiable until approximately 4 1/2
weeks with a transvaginal scan.
• Gestational sac size should be determined by
measuring the mean of three diameters. These
differences rarely effect gestational age dating by
more than a day or two.
5 week gestation
Yolk Sac Only seen.
The yolk sac will be visible before a
clearly definable embryonic pole.

10. Mean Sac Diameter measurement is used to determine
gestational age before a Crown Rump length can be clearly measured.
The average sac diameter is determined by measuring the length, width
and height then dividing by 3.

12. A Yolk Sac is first anatomical structure identified within
the gestational sac.
It plays a critical role in embryonal development by providing
nutrients, serving as the site of initial haematopoiesis and
contributing to the development of gastrointestinal and
reproductive systems

13. The yolk sac appears during the 5th week.
It is the second structure to appear after the GS.
It should be round with an anechoic centre.
It should not be calcified, misshapen or >5mm from the inner to inner diameter.
Yolk sacs larger than 6 mm are usually indicative of an abnormal pregnancy.
Failure to identify (with transvaginal ultrasound) a yolk sac when the
gestational sac has grown to 12 mm
is also usually indicative of a failed pregnancy.

14. Visualization of a yolk sac is useful in distinguishing an intrauterine
pregnancy (IUP) from a pseudo gestational sac, a decidual cast
cyst or a blighted ovum, as it is only seen in theIUP.
A yolk sac should always be seen when the mean sac diameter (MSD) is 20
mm on trans-abdominal scanning and usually seen trans-vaginally with an
MSD of 8 - 10 mm.
In general if the MSD is 16 mm or greater and no fetal pole / yolk sac can be
identified on trans-vaginal scanning then this suggests a non-viable
pregnancy (an-embryonic pregnancy).
Repeat scanning with an larger MSD and serial quantitative beta-HCGs is
however thought prudent.
In a normal early pregnancy, the diameter of the yolk sac should usually be
< 6 mm while its shape should be near spherical.
Visualisation multiple yolk sacs is the earliest sign of a polyamniotic
pregnancy, e.g twins.
Natural course

15. Double Decidual Sac Sign (DDSS) is a useful feature
on early pregnancy ultrasound in distinguishing between
an early intrauterine pregnancy (IUP) and
a pseudogestational sac.
It consists of the Decidua Parietalis (that lining the uterine
cavity) and Decidua Capsularis (lining the gestational sac)
and is seen as two concentirc rings surrounding an anechoic
gestational sac.
Where the two adhere, is the Decidua Basalis, and is the
site of future placental formation.
With good quality high frequency transvaginal scanning
a yolk sac should also be present at this time.
Should a definite IUP not be confirmed on sonography
then repeat scanning and serial quantitative beta-HCGs are
required, until either an IUP is established, an ectopic
pregnancy is visualised or beta-HCGs return to zero
(implying miscarriage).

17. • A Double Bleb Sign is a sonographic
feature where there is visualisation of a
gestational sac containing a yolk
sac and amniotic sac giving an
appearence of two small bubbles.
• The embryonic disc is located between
the two bubbles.
• It is an important feature of an
intrauterine pregnancy and thus
distinguishes a pregnancy form
a pseudogestational sac or decidual cast
cyst.
• It should not be confused with
the double decidual sac sign.
Yolk sac
Embryonc
Disc
Amniotic sac

18.  The CRL is a reproducible and accurate method for measuring and dating
a fetus.
 After 12 weeks, the accuracy of CRL in predicting gestational age
diminishes and is replaced by measurement of the fetal biparietal diameter.
 In at least some respects, the term "crown rump length" is misleading:
there is no fetal crown and no fetal rump to measure in 1st trimester.

19. Until 53 days (9weeks) from the LMP, the most caudal portion of the fetal cell
mass is the Caudal Neurospone, followed by the tail.
Only after 53 days (9weeks) is the fetal rump the most caudal portion of the
fetus.
Until 60 days (10.5 weeks) from the LMP, the most cephalad portion of the
fetal cell mass is initially the Rostral Neurospore, and later the cervical
flexure.
After 60 days (10.5 weeks), the fetal head becomes the most cephalad portion of
the fetal cell mass.
What is really measured during this early development of the
fetus is the longest fetal diameter.
From 6 weeks to 9 1/2 weeks gestational age, the fetal CRL grows at a
rate of about 1 mm per day.

20. • Crown Rump Length (CRL) measurement in
a 6 week gestation.
• A mass of fetal cells, separate from the yolk
sac, first becomes apparent on transvaginal
ultrasound just after the 6th week of gestation.
• This mass of cells is known as the Fetal Pole.
• The fetal pole grows at a rate of about 1 mm a
day, starting at the 6th week of gestational age.
• Thus, a simple way to "date" an early
pregnancy is to add the length of the fetus (in
mm) to 6 weeks.
• Using this method, a fetal pole measuring 5
mm would have a gestational age of 6 weeks
and 5 days.

21. Outside to Outside Measurements

22. Using a transvaginal approach the fetal heart beat can be seen flickering before the fetal pole
is even identified.
It will be seen alongside the yolk sac.
It may be below 100 beats per minute but this will increase to between 120- 180 beats per
minute by 7 weeks.
In the early scans at 5-6 weeks just visualising a heart beating is the important thing.
Failure to identify fetal cardiac activity in a fetus whose overall length is greater than 4 mm
(approx 4.5 weeks)is an ominous sign .
Sometimes there is difficulty in distinguishing between the maternal pulse and fetal heart
beat. Often technicians will take the mothers pulse at the same time to check if it is the fetus
or the mothers .

23. The very early embryonic heart
will be a subtle flicker.
This may be measured using M-
Mode(avoid Doppler in the first
trimester due to risks of
bioeffects).
Initially the heart rate may be
slow.
Compare to the maternal heart
rate to confirm that one is not
seeing an arteriole.

25. 8 weeks
A normal 8 week foetal
pole.
One should see a
definable head and
body.
The beginning of the
limb buds.
The fetal heart should
be easily visible.
Subtle body movements
can often be seen.

26. NOTE- Demarcation between the
Chorion & Amnion
The 2 sacs are clearly visible.
The outer chorion with the
developing placenta and the
inner amnion which will
"inflate" with the production
of fetal urine, to adhere to the
chorion obliterating the
residual yolk sac.
The normal small mid-gut
hernia into the cord is still
visible (pink shading).
This is the result of normal
midgut proliferation and will
resolve by 11 weeks as the
fetus lengthens.
This physiological occurrence
should not be confused with
an omphalocele.

27. The Nuchal Translucency is a
measurement performed during a
specific period in the first
trimester (11.3-13.6 weeks).
It should not be confused
with Nuchal Thickness which is
measured in the second trimester.
An increased nuchal translucency
is thought to relate to dilated
lymphatic channels.

28. It can being associated with a number of anomlaies including :
ANEUPLOIDY
Trisomies – 13, 18, 21.
Turner syndrome
NON-ANEUPLOIDIC STRUCTURAL DEFECTS &
SYNDROMES
Congenital Diaphragmatic Herniation
Congenital Heart Disease
Omphalocoele
Skeletal Dysplasias
Smith-Lemli-Opitz Syndrome
VACTERL association

29. VACTERL association (also VATER syndrome) is a non-random
association of birth defects.
The reason it is called an association, rather than a syndrome is that
while the complications are not pathogenetically related they tend to
occur together more frequently than expected by chance.
No specific genetic or chromosome problem has been identified.
Can be seen with some chromosomal defects such as Trisomy 18 and is
more frequently seen in babies of diabetic mothers.
Most likely caused by multiple factors.

30. ANAL DEFECTS
1. Atresia
2. Imperforate Anus
VERTEBRAL DEFECTS
1. Hypoplastic Vertebrae
2. Hemi-vertebrae
3. Scoliosis

31. TRACHEO-ESOPHAGEAL
DEFECTS
1. T.O Fistula
2. Esophageal Atresia
CARDIAC DEFECTS
1. VSD
2. ASD
3. TOF
4. TpGV
5. Truncus Arteriosus

32. LIMB DEFECTS
1. Hypoplastic /
Dysplastic thumb
2. Polydactyly
3. Syndactyly
4. Radial Aplasia
RENAL DEFECTS
1. Single Umbilical
Artery
2. Incomplete formation
of kidney(s).
3. Outflow obstruction
4. Severe reflux

33. Nuchal lucency is measured on a sagittal section through the
fetus.

34. Use of the correct technique is essential
 The fetus should be transverse (sagittal) in the imaging plane
The vertebral column should be facing the bottom of the screen.
 Fetal head should not be extended or flexed
 Fetus should be floating free of the uterine wall (i.e. amniotic fluid should be
seen between its back and the uterus)
 Only the lucency is measured (again differing from nuchal thickness)
 Ideally only the head and upper thorax should be included in the measurement
 The level of magnification should be appropriate (fetus should occupy most of
the image) enabling 1mm changes in measurement possible.
 The " + " calipers should be used for measurement
 The widest part of the measurement should be taken

35. 1. Only values obtained when CRL values are between 45-
84 mm are considered valid.
2. The lucent region is generally not septated.
3. The thickness rather than the appearance (morphology) is
considered to be directly related to the incidence of
chromosomal and other anomalies.
4. A normal value is usually less than roughly 2.5-3.0 mm in
thickness however it is
maternal age dependent and
needs to be matched to exact
gestational age and crown rump
length (CRL).

36. The nuchal translucency cannot be adequately
assessed if there is -
Unfavourable fetal lie
Unfavourable gestational age - CRL < 45 or > 84
mm.

38. Most likely a case of
Hydrops Fetalis-
1.Incresed NT.
2.Oedema under the
skin.
3.Evidence of
Ascites.

40. Interpretation
• Detection rates for aneupliodic
anomalies with nuchal translucency
alone approaches 80 - 90 % with a
false positive rate of ~ 5%.
Correlation With Serum Markers
• To increase the clinical accuracy of nuchal
lucency, it can be correlated with
serum markers such as
• Maternal B-HCG
• Alpha Feto Protein (AFP)
• Pregnancy Associated Plasma Protein
A (PAPP-A)
• Oestriol
Further work up
• If abnormal > further work up is
carried out which includes
• Amniocentesis and / or Chorionic
Villus sampling
• Fetal echocardiography
Natural course - progression
• As the second trimester approaches, the
region of nuchal translucency might either
• Regress :
– if chromosomally normal, a large
proportion of fetuses will have a normal
outcome
– spontaneous regression does not
however mean a normal karyotype
• Evolve into a
– Nuchal Oedema
– Cystic Hygroma

41. Hydatidiform mole (HM)
is one of the commonest and most benign form
of Gestational Trophoblastic Disease.

42. COMPLETE HYDATIDIFORM MOLE
Extremely variable
Classic sonographic appearance solid collection of echoes
with numerous small (3 - 10 mm) anechoic spaces
SNOWSTORM OR GRANULAR APPEARANCE
BUNCH OF GRAPES SIGN which represents hydropic
swelling of trophoblastic villi.

43. COMPLETE HYDATIDIFORM
MOLE

46. • A CRL of ≥ 7mm without a heart
beat on a transvaginal ultrasound
confirms the diagnosis
(by RCOG criteria).
• Additional clues are presence of
abnormal hyperechoic material
within the uterine cavity and an
irregular gestational sac.
• If there is an absence of heart beat in a
fetus that is less than 7mm, the
diagnosis of miscarriage cannot be made
with certainty.
• This scenario is termed "Pregnancy
Of Uncertain Viability (PUV)",
and followup with ultrasound (generally
in 7-10 days) and serial bHCG
recommended.

47. • Irregular Sac.
• Hyperechoic collection
within the sac.

48. • Refers to the presence of an
open cervix in the context of
bleeding in the first trimester of
pregnancy.
• Essentially, a threatened
abortion progresses to an
inevitable abortion if cervical
dilatation occurs. Once tissue
has passed through the cervical
os, this will then be termed an
incomplete abortion and
ultimately a complete abortion.

49. A subchorionic
haemorrhage is often
seen, but unless large
does not carry a poor
prognosis.
Features which do
predict poor outcome
include:
• Fetal bradycardia : <
80 - 90 bpm
• Small or
Irregular Gestational
Sac : MSD - CRL < 5 mm
• Large Subchorionic
Haemorrhage

51. One important difference is to be deduced between an
actual irregular sac & a sac which appears irregular due to
Braxton-Hick’s contractions.
The former one, will not change its shape to become
normal with time.
However, the later, will change shape with time. The patient
is allowed to lay at rest for few minutes & put the probe
again to confirm. A changed contour of the sac / regular
appearing sac on 2nd look, helps the jeopardy.

52. Shows an empty
uterus with no
fetal
components or
products of
conception

53. Retained
Products of
Conception, still
seen within the
uterine / cervical
cavity.

54. BLIGHTED OVUM
An anembryonic
pregnancy may be
diagnosed when there
is no fetal
pole identified on
trans-vaginal scanning
the size of the gestational
sac is such that a fetal
pole should be seen
MSD ≥ 25 mm (by RCOG
criteria)
There is little or no growth
of the gestational sac
between interval scans
Normally the MSD
should increase
by 1 mm per day
If MSD is too small to
ascertain viability on the
initial ultrasound, a follow up
scan in 10-14 days should
differentiate early pregnancy
from a failed pregnancy

55. Other ancillary features include
 Absent yolk sac when MSD > 8 mm
Poor decidual reaction : often < 2 mm
 Irregular gestational sac shape
 Abnormally low sac position

57. ECTOPIC GESTATION
UTERUS
Empty uterine cavity / no evidence of intra-uterine pregnancy
Pseudogestational sac / decidual cyst - may be seen in 10 – 20 % of
ectopic pregnancies
Decidual cast
TUBE AND OVARY
Simple adnexal cyst : 10% chance of an ectopic
Complex adnexal cyst / mass : 95% chance of an tubal ectopic
Tubal ring sign :
95% chance of an tubal ectopic if seen
described in 49 % of ectopics and in 68 % of unruptured ectopics
Ring of fire sign : can be seen on colour Doppler in a tubal ectopic

58. PERITONEAL CAVITY
Free pelvic fluid / Haemoperitoneum in
the Pouch Of Douglas
The presence of free intra peritoneal
fluid in the context of a positive beta
HCG and empty uterus is
~ 70% specific for an ectopic
pregnancy
~ 63% sensitive for an ectopic
pregnancy
Live Pregnancy : 100% specific, but only
seen in a minority of cases

59. TUBAL ECTOPIC : 93 - 97%
Ampullary Ectopic : most common : ~ 70 % of tubal ectopics and ~ 65 - 68 % of all
ectopics
Isthmal Ectopic : ~ 12 % of tubal ectopics and ~ 11 % of all ectopics
Fimbrial Ectopic : ~ 11 % of tubal ectopics and ~ 10 % of all ectopics
ATYPICAL ECTOPIC PREGNANCIES
Interstitial Ectopic - cornual ectopic : 3 - 4 % : also essentially a type of
tubal ectopic
Ovarian Ectopic - ovarian pregnancy : 0.5 - 1%
Cervical Ectopic - cervical pregnancy : rare < 1 %
Scar Ectopic : site of previous Caesarian section scar : rare
Abdominal Ectopic : rare ( ~ 1.4%)

61. Transvaginal scan showing fluid
with debris at the
cul-de-sac
Empty endometrium
with a normal size

62. The presence of Ring of Fire sign, confirms
the anechoic shadow to be a GS.
Color and spectral doppler
demonstrates a right anechoic tubal mass
with tracings similar to fetal heart rate
"RING OF FIRE" SIGN
(HYPERVASCULAR RING)

64. LEVEL -I (SCREENING) SCANNING
consists of the basic evaluation.
It is usually relatively simple to
perform, readily available, and
relatively inexpensive.

65. LEVEL -II (TARGET) SCANNING
Requires higher resolution (more expensive) equipment and
sonographic skills that are more limited in their availablity
and significantly more expensive.
Indications for a level II scan may include:
•Suspicious findings on a level I scan
•History of prior congenital anomaly
•Insulin dependent diabetes or other medical problem that increases the
risk of anomaly.
•History of seizure disorder, particularly if being treated with medications
known to increase the risk of anomaly.
•Teratogen exposure
•Elevated MSAFP
•Suspected chromosome abnormality
•Symmetric IUGR
•Fetal arrhythmia
•Oligohydramnios, hydramnios
•Advanced maternal age

66. 2nd trimester scan is a routinely performed ultrasound examination
on all pregnancies .
This scan emphasizes on fetal anatomy and therefore is also called a
2nd Trimester Anatomy Scan
OR
Fetal Anomaly Scan
OR
TIFFA (Targeted Imaging For Fetal Anomalies) Scan.
Period extends from 13 weeks 0 days to
27 weeks 6 days

67. - Integrity / Shape
- Ventricles, Choroid Plexus, Mid Brain, Posterior Fossa
- Profile, Orbits (including Interocular Diameter
And Binocular Diameter), Upper Lip
- Nuchal Thickness
- Transverse As Well As Longitudinal Views
Fetal Heart Rate / Rhythm
Four Chamber View
Outflow Tract Views
Aortic Arch View

68. - Thoracic Shape, Size, Lungs, Diaphragm
- Stomach (including Situs), Liver, Kidneys, Bladder,
Abdominal Wall, Umbilicus
- Echogenicity, Measurements, Hands, Movements
In addition to this, Standard Fetal Biometric Parameters
as well as the following features are also assessed
Fetal Lie
Placental Localisation & Maturity Grading
Liquor Volume
Umbilical Cord : Number Of Cord Vessels

69. Round Skull shadow.
Middle Fossa in focus
here.

70. Cavum Septum
Pellucidum
ThalamusLateral Lobe
Vermis
Cisterna
Magna
Choroid Plexus

71. Measured at a focus which shows, both the
THALAMI & the CAVUM SEPTUM
PELLUCIDUM, preferably with the Sylvian
Fissure, in the same image.
Both the thalami when seen together, as two
anechoic structures, represent the
“Trishool Sign”

72. Accuracy – +/- 7 to 10 days upto 24 weeks & +/- 2 to 3 weeks during the 3rd
trimester.
Measurement
The 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 image
BPD

73. • Not useful when the head shape is abnormal i.e, elongated (Dolicocephaly)
or excessively round (Brachecephaly).
• Better to use the parameter of CEPHALIC INDEX (CI), instead of BPD
alone.
• Also, the CI remains constant during the 3rd trimester.
• BPD is commonly effected by fetal position. Eg. Breech presentation.
Cephalic Index (CI) = Bipareital Diameter (BPD) / Occipitofrontal Diameter
(OFD) X 100

74. • The cephalic index gives an idea of the fetal head shape.
• It can change according to various situations such as
1. Presentation : e.g. Breech presentation
2. Ruptured membranes
3. Presence of a twin pregnancy
• The usual range is variable depending on various sources
and different demographic groups.
• Often the mean value is taken ~ 78 (range 74 - 83)
• An grossly decreased cephalic index suggests Dolichocephaly while a grossly
increased one can suggest Brachycephaly.

75. OCCIPITO-FRONTAL DIAMETER
Measured between the most prominent part of
the occipital bone & the frontal bone.
The area in focus is the same which shows both
the thalami, as in BPD.
Anterior Horn Of The Lateral Ventricle (Va)
Posterior Horn Of The Lateral Ventricle (Vp)
Hemisphere (Hem)

77. Recently , a lot of stress is
being laid on measuring of
the TCD.
It is believed to be effected
at last and the least in cases
of IUGR

78. •Transcerebellar
Diameter (TCD)
•Cisterna Magna (CM)
•Nuchal Fold (NF)
Measured from the outer margin of one
cererbellar hemisphere to the outer margin
of the other cerebellar hemisphere, including
both the hemispheres & the vermis

80.  The area of scan is the same as that for BPD & OFD measures, i.e the
thalami & cavum septum should be seen.
 An ellipsoid should be used to mark out the fetal skull at its outer
borders (as far as possible).
Unaffected by
head shape.
Towards the end of
pregnancy, it is the
best indicator of
Gestational Age.
Not effected in
IUGR, until
vary late stages.

81. The brain tissue, except the a portion of the brainstem is completely absent/fails
to develop.
No skull vault / cranium is seen.
FROG EYES SIGN – two hollows, that of the orbits are seen prominently.
ACRANIA – the term is used when the
cranium is absent & major part of the
brain tissue is present .

82. Anencephaly
(Frog Eye Sign)
Acrania
(absent Cranium
But Brain tissue present)

83. An ENCEPHALOCOELE is
a type
of cephalocoele where
intracranial tissue herniates
out through a defect in the
cranium.
Meningocele when it
contains only meninges
Meningoencephalocele if
brain tissue is included in
the herniated tissue.

84. May be seen as a purely
cystic mass or may contain
echoes from herniated
brain tissue.
If the mass appears
cystic, the Meningoecele
component predominates,
while a solid mass
indicates predominantly
an Encephalocele.
Larger encephalocoeles
may show accompanying
microcephaly.

85. • The choroid plexus within the
dilated ventricles are relatively
small & looses contact with the
medial & lateral wall.
• A very common appearance of
choroids plexus is DANGLING
CHOROID.
• A separation of upto 5 mm from
ventricular wall may be considered
normal.
Lateral ventricle with greater than
10mm diameter is suspicious of
VENTRICULOMEGALY.
10-12 mm is taken as borderline.
Ventriculomegaly is diagnosed surely,
when the choroid plexuses lose contact
with one / both walls

87.  May be Unilateral or Bilateral.
Usually transient & benign.
 Seen in fetus normally between
16 – 21 weeks, after which they start
regressing.
 Normally not seen after 25 weeks.
Association with chromosomal
anomaly is less than 1%.

88. Rare congenital brain malformation, resulting from incomplete
separation of the two hemispheres.
The three main sub types, in order
of decreasing severity are :
1. Alobar Holoprosencephaly
2. Semilobar Holoprosencephaly
3. Lobar Holoprosencephaly

89. Single ventricle- Horseshoe shaped
appearance.
Hemispheres are fused to form a mass
around the ventricle.
 Thalami are fused & no Falx Cerebri is
seen.

90. Horseshoe Shaped Appearance

92. LOBAR PROSENCEPHALY
a. Nearly complete separation of
the hemispheres with the falx.
b. Anteriorly, the frontal horns of
lateral ventricles are fused (so
is the frontal brain
parenchyma). Thus, attaining a
triangular shape.
c. Septum pellucidum is absent.
d. Thalami are separate.

93. The basic structure of
the cerebral lobes are
present, but are fused
most commonly
anteriorly and at the
thalami and there is
partial diverticulation of
brain.
o Absence Of Septum Pellucidum
oMonoventricle With Partially Developed
Occipital And Temporal Horns
o Rudimentary Falx Cerebri : Absent Anteriorly
o Incompletely Formed Interhemispheric
Fissure
o Partial Or Complete Fusion Of The Thalami
o Absent Olfactory Tracts And Bulbs
o Agenesis Or Hypoplasia Of The Corpus
Callosum
o Incomplete Hippocampal Formation

95. • Due to B/L occlusion of the Internal Carotid Arteries.
• Resulting infarction of the entire brain, except the Posterior Fossa,
which is supplied by the Vertebral Arteries.
• It appears as a large empty cranial vault filled with fluid without any
cortical brain parenchyma matter, within.

97. DANDY-WALKER CONTINUUM consists of a group of anomalies where
there is a posterior fossa cyst which communicates with the fourth ventricle
as well as abnormal development of the vermis.
There are numerous forms, and the classification is contentious.
The forms which are typically included in the Dandy-Walker
spectrum include:
Dandy-Walker Malformation (Classic)
Dandy-Walker Variant
Other included conditions
Fourth Ventriculocoele
Blake’s Pouch Cyst
Mega Cisterna Magna

98. Classically Dandy Walker malformation
consists of the triad of :
1. Hypoplasia of the vermis
2. Cystic dilatation of the fourth ventricle
extending posteriorly.
3. Enlarged posterior fossa
Antenatal ultrasound may falsely over
diagnose the condition if scanned before
18 weeks due to the vermis not being
properly formed before that time.

99. DANDY WALKER
VARIANT
Partial vermian hypoplasia
with partial obstruction to
the fourth ventricle, but
without enlargement of
the posterior fossa

100. CLASSICAL
DANDY WALKER
MALFORMATION
DANDY WALKER
VARIANT
MEGA
CISTERNA MAGNA

101. Relatively common congenital
malformation of the spine and
posterior fossa characterised by
lumbosacral spina bifida aperta /
myelomeningocoele and a small
posterior fossa with descent of the
brain stem.

102. Classical signs described on ultrasound include:
LEMON HEAD SIGN
BANANA CEREBELLUM SIGN
There may also be evidence of fetal Ventriculomegaly due to obstructive
effects as a result of downward cerebellar herniation.
Additionally many of the associated malformations (e.g. Corpus Callosal
Dysgenesis) may be identified

103. Classical
LEMON HEAD SIGN
Breech in continuity of the skin over the
spinal cord, suggestive of Spina Bifida
(seen here at the lumbosacral area, as evident by
the bladder seen in front of the spine)

105. • Varying degrees of protrusion of the Vermis, 4th Ventricle &
Medulla through the Foramen Magnum, into the spinal cord.
• As a result, Cisterna Magna can be obliterated or reduced.
• Cerebellar hemispheres come closer producing a BANANA SIGN.
• Hydrocephalus due to obstruction in lower ventricular area
causing varying degrees of ventricular dilatation.
• Fetal bones angulate inwards, producing the LEMON HEAD
SIGN.
(may be seen with Encephalocoele & Thanatophoric Dysplasia)

106. Several diagnostic points should be remembered
about this sign:
1. When obtaining images of the calvarium, the
transducer should not be angled downward
anteriorly, as the fetal orbits may simulate the
lemon sign.
2. Seen more often in fetuses less than 24 weeks
and may not be present in older fetuses
(usually disappears after 24 weeks 4 ).
3. This may be due to the decreased pliability of
the fetal calvarium with advancing gestational
age or the increased intracranial pressure with
associated hydrocephalus
4. This sign may be rarely seen in normal
patients
( ~ 1 % of cases) and in those with other non-
neural axis abnormalities.
It is seen on axial
imaging
(usually antenatal
ultrasound, although
antenatal MRI will also
demonstrate this sign)
through the head
and relates to
concavity
(not just flattening)
of the frontal bones.

109. DOLICOCEPHALY BRACHYCEPHALY
CLOVER LEAF SKULL
(Thanatotropic Dysplasia)

110. NUCHAL THICKNESS
is a parameter that is
measured in a second
trimester scan (18 - 22
weeks)
and
it is not to be confused
with Nuchal
Translucency (which is
measured in the first
trimester).

111. The nuchal thickness is measured on an axial section through the
head and the level of the thalami, cavum septi pellucidum &
cerebellar hemispheres
(i.e in the same plane that is used to assess posterior fossa structures).
One caliper should be placed at the skin, and the other against the
outer edge of the bone of the occiput.

112. An abnormal value is one that is more
than 6 mm in thickness.
A thick nuchal fold is often considered the most sensitive and most
specific (best) 2ndtrimester marker for Down syndrome with false positive
rates as low as 1%.

113. The increase in nuchal fold thickness can be due to-
Scalp Edema - Down’s Syndrome, IUFD, Hydrops Fetalis.
Lymph- Cystic Hygroma.
Brain Matter - Early Encephalocoele.
Fat – Macrosomia.

114. Associations
• ANEUPLOIDY
– Trisomies
– Turner syndrome
• CONGENITAL
HEART DISEASE
NATURAL COURSE
Most thickened nuchal folds
tend to resolve towards the
third trimester but that does
not decrease the increased
risk of aneuploidic anomalies.

115. The arrow shows a cystic growth arising from the
neck (posteriorly).
16 week fetus with a septate cystic mass in
the posterior and lateral aspect of the fetal
neck.

116. Color Doppler image shows that this mass
is not the cord or part of it.
Fetal head shows evidence of
mild scalp edema (early fetal
hydrops).
The fetal spine and calvarium
show no bony defects, thus
ruling out the possibility of
fetal meningocele or myelo-
meningocele, encephalocele
etc.

117. Sagittal image of the fetal head and neck shows a large complex mass anterior in the
neck (arrows and cursors).
Postnatal diagnosis was a teratoma.

120. Measuring the Outer
Orbital Diametre
Measuring the
Inter Orbital Diametre

121. Profile used to see the Nose, Upper
Lip, Lower Lip, Chin, Philtrum,
Glabella.
Profile used to see the Orbits, the
Inta-Orbital Distance (IOD).

123. MICROGNATHIA
SEVERE
HYPER-TELORISM

126. Sagittal scan & post mortem fetus showing-
PROMINENT
FOREHEAD
RETROGNATHIA

128. 1. Lungs of normal echogenicity,
homogenous
2. Apex of the heart points to the
front and left
3. Right chamber closer to the
thorax, seems shorter and
coarser than the right one
4. Both ventricles of the same size
5. Both atria of the same size
6. Continuity of the
interventricular septum
7. Continuity of the interatrial
septum

129. • Diaphragm completely divides
thorax from the abdomen
• Stomach in the abdomen only
• Thorax of the normal size
compared to the abdomen

130. Descending Aorta & Aortic Arch
with the branches for head and neck

132. FORAMEN
OVALE / FORAMEN BOTALLI
/ OSTIUM SECUNDUM OF
BORN / FALX SEPTI
allows blood to enter the
left atrium from the right
atrium.

134. CONGENITAL DIAPHRAGMATIC
HERNIA
Group of defects in which some parts of the
abdominal contents protrude into the chest
cavity.
The prenatal USG diagnosis s based on –
• Abdominal Organs seen within the
thoracic cavity. A left sided hernia may
be diagnosed by observing the
Stomach/Bowel, to be partially
/completely within the thorax.
• Shift in position of the heart /
Cardiac Compression
(Mediastinal Shift)
•Polyhydramnios is a common
associated finding, rarely observed
before 24 weeks gestation.
It is thought to be due either to
esophageal compression
{kinking of the stomach} or reduced
absorption of fluid by the hypoplastic
lungs.

135. • A Right-sided Hernia may be harder to diagnose because of the
similar echogenicity of the lung and liver tissue, but the condition
should be suspected by the presence of mediastinal shift or
hydrothorax.
• Other signs include an abnormal position of the
gallbladder, hepatic veins or even umbilical veins.

136. 1. Postero-lateral Defect / BOCHDALEK HERNIA
90% cases in neonatal period.
80% left sided, 15% right sided, 5% bilateral.
2. Parasternal / MORGAGNI HERNIA
1-2% cases.
Located on the anterior portion of the diaphragm.
More often Right sided / bilateral, mostly involving the liver.
3. SEPTUM TRANSVERSUM Defect
Due to defect of the Central Tendon.
4. HIATAL HERNIA
Due to congenitally large esophageal orifice.
5. Eventration of the Diaphragm
5% cases.
More common on right side.
Abdominal contents move upwards due to a weak diaphragm which cant hold them in
place.

139. • Pentalogy of Cantrell (or Thoraco-abdominal Syndrome) is a
rare syndrome that causes defects involving the diaphragm,
abdominal wall, pericardium, heart and lower sternum.
• The syndrome has five characteristic findings:
a. Omphalocele
b. Anterior Diaphragmatic Hernia
c. Sternal Cleft
d. Ectopia cordis
e. Intracardiac Defect: either a Ventricular Septal Defect or
a Diverticulum of the Left Ventricle

142. ABDOMINAL CIRCUMFERENCE
(AC)
Transverse section (coronal) through the
fetal abdomen at the level where the umbilical vein enters the liver.
(seen as a J shape structure within the liver parenchyma)
AC may be measured directly, or calculated from the AP and transverse abdominal
measurements.
Both techniques give good results.
Although the AC can be used to calculate gestational age, it is more useful in
determining fetal weight.

143. LIVER PARENCHYMA
UMBILICAL VEIN
ENTERING
THE LIVER
(J-shape)
FETAL STOMACH
BUBBLE
FETAL VERTEBRA

145. Loosely identified as the
MICKEY MOUSE SIGN
2 Umbilical Arteries &
1 Umbilical Vein
easily visible.
It is essential to identify the place of
insertion of the cord in the fetal
abdomen

147. Can occur with various physiological as well as pathological processes.
It becomes a significant sonographic observation after 14 weeks of gestation
(about the time the fetus begins to swallow)

148.  Physiological Emptying : Transient
 Lack Of Amnionitc Fluid To Swallow
Oligohydramnios
Anhydramnios
 Impaired Fetal Swallowing
Oesophageal Atresia : particularly those without a tracheo-oeseophageal fistula
 Obstructing Oropharyngeal Mass
Cervical Teratoma
Epignathus
 CNS abnormalities
Facial Clefts
 Neuromuscular Disorders
Microgastria
Congenital Diaphragmatic Herniation : fetal stomach may be absent in an axial
ultrasound scan - standard view due to migration into the thorax

149. Persistent non
visualisation of the
stomach / Persistent small
stomach.
Associated commonly
with polyhydramnios.
Associated Tracheo-
Oesophageal Fistula.

150. Extra-abdominal herniation (evisceration) of fetal or neonatal bowel
loops (and occasionally portions or the stomach and or liver) into the
amniotic cavity through a para-umbilical abdominal wall defect.

151. The herniated content is free floating
bowel in most cases.
Classically, the contents are not
covered/contained within a covering
membrane.
Colour Doppler may be useful
to locate the cord in relation to
the herniation.
This causes the fetal
abdominal circumference to
be smaller than expected for
gestation age.
The herniated bowel wall can
be thickened due to oedema.

152. Marked bowel dilatation,
which may be either
external or internal to the
abdominal cavity, suggests
bowel obstruction and/or
ischemia

153. Omphalocoeles (or Exomphalos)
are congenital midline abdominal wall defects at the base of
the umbilical cord insertion with herniation of gut
(or occasionally other content) out of the fetal abdomen.

154. • Multiple bowel loops
(and on occasion liver)
herniate into a membrane-
covered defect (i.e not free
flowing)
• The umbilical cord
insertion is directly into
the omphalocoele
• May also show evidence
of polyhydramnios.
• The abdominal
circumference may be
smaller as a result

155. MEDIAL
OMPHALOCOELE
 Cord inserted in front
of the omphalocoele.
 Chances of association with
other anomalies is more

156. The herniated bowel is NOT
directly exposed to amniotic fluid
Bowel usually does not thicken or
dilate

157. PSEUDO-OMPHALOCOELE
Caused by excessive transducer pressure / oblique
scanning of the abdomen.

158. Results from a congenital
malformation of
the duodenum, and
requires prompt
correction in the
neonatal period.
It is considered to be one
of the commonest causes
of a fetal bowel
obstruction.

159. May classically show a
DOUBLE BUBBLE
SIGN
with gas filled distended
stomach and duodenum with
an absence of distal gas.
A similar appearance (either
filled with fluid or gas) can be
seen with other imaging
modalities.

160. Two cystic structures
in the abdomen that
communicate with
each other
Classic “Double
Bubble”

161. MECONIUM
PERITONITIS
Refers to a sterile chemical peritonitis due to intra-uterine
bowel perforation & spillage of fetal meconium into the fetal
peritoneal cavity.
It is a common cause of peritoneal calcification.

162.  May show highly echogenic linear or clumped foci which represent calcifcation .
 Can also give a snowstorm appearance .
 May show fetal ascites (most common antenatal sonographic finding ) and / or
polyhydramnios.
 The abdominal circumference may be increased.
 May also show associated anomalies such as dilated fetal bowel and / or
Meconium Pseudocysts.

163.  Continuity of the spinal
tract.
 Continuity of the skin
over the fetal spine.
 Called as the
RAIL ROAD/TRACK
PATTERN

164. SPINA BIFIDA is a type of neural tube defect / SPINAL DYSRAPHISM which can
occur to varying severity.
It is often considered the most common congenital CNS malformation.
Splaying Of The Spine

165. There are many ways of classifying a spina bifida.
A. One method is according to Extent Of The Defect
• Spina Bifida Aperta - open defect
• Spina Bifida Aperta Without Cystica
• Spina Bifida Cystica
• Rachischisis
• Spina Bifida Occulta : defect closed by skin
B. Another method is according to Position
o Anterior (Ventral)
o Posterior (Dorsal)

166. C. They can also be sub typed as:
Open (80 – 90%)
Closed
D. Further method is according to the Presence Of An Overlying Covering
Covering Present
Meningocoele
Myelomeningocoele
Covering Absent
Myeloschisis

167. MENINGOCOELE MYELOMENINGOCOELE

168. Discontinuity at the Sacral Segment is
visible
Overlying skin
at the Sacral Spine is
missing

170. Anterior Wall Placenta
with Cord insertion seen.
LAMBDA SIGN /
TWIN PEAK SIGN
(Dichorionic Gestation)

171. When the placenta extends into the lower uterine segment and its edge
lies too close to the internal os of the cervix,
with / without covering it.

172. COMPLETE PLACENTA
PRAEVIA
MARGINAL
PLACENTA PRAEVIA

173. PSEUDO- PLACENTA
PREVIA
1st scan shows the
placenta covering the os.
2nd scan done after
10-15 mins, shows the
placental edge is away
from the os & instead the
head of the fetus is at the
os.
The placenta is seen low lying due to
Braxton-Hick’s Contractions

174. The retro placental area is to
be examined for any
Echogenicity seen behind it /
Gap between the placenta &
the myometrium /

175. Large retro-placental haematoma
seen as a mixed echogenic area,
separating the placenta from the uterine
wall.

176.  Hyper-echoic placental mass or Placental thickening which can resemble
chorioangiomas.
 Hyper-echoic areas can be predominant over the maternal surface of placenta &
can extend onto the placenta as well.
 Subchorionic cysts may be seen.

177. Patient with severe pre-eclampsia
showing great degree of ischemia with
degeneration of the placental tissue.

178. CIRCUMVALLATE PLACENTA
The chorionic membranes hanging
instead of attaching to the
margin of the placental disc.
SONOGRAPHIC FINDINGS
The margins of the placenta
can be seen curled in on
themselves, rather than
attaching on the placental disc.

179. SUCCENTURIATE LOBE
An accessory lobe of the
placenta, separate from the
main placental tissue is seen.

180. GRANNUM’S GRADING SYSTEM
Grade 0 : < 18 Weeks
Uniform Echogenicity
Smooth Chorionic Plate
Grade I : 18 - 29 Weeks
Occasional Parechymal Calcification / Hyper-echoic Areas
Grade II : > 30 Weeks
Occasional Basal Calcification / Hyper-echoic Areas
May Also Have Comma Type Densities at the Chorionic Plate.
Grade III > 39 Weeks
Significant Basal Calcification
Chorionic Plate Interrupted By Indentations
An Early Progression To A Grade III Placenta In Concerning & is sometimes
associated with Placental Insufficiency

181. GRADE – 0
Uniform moderate echogenicity
Smooth chorionic plate without indentations
GRADE – 1
Subtle indentations of chorionic plate
Small, diffuse calcifications (hyperechoic)
randomly dispersed in placenta

182. GRADE – 2
 Larger indentations along chorionic plate
 Larger calcifications in a “DOT-DASH”
configuration along the basilar plate
•
GRADE – 3
• Complete indentations of chorionic plate through
to the basilar plate creating “Cotyledons”
(portions of placenta separated by the
indentations)
• More irregular calcifications with significant
shadowing
• May signify placental dysmaturity which can cause
IUGR

184. • The amniotic fluid index (AFI) is an estimate of the amniotic fluid
volume in a fetus.
• It is measured by adding the values of individual amniotic pocket
depths (in cm's) for each of the four quadrants
• Care should be taken that the pocket chosen is free from the cord or
any fetal part or placental tissue.
• It is part of the fetal biophysical profile.
The normal range for amniotic fluid volumes varies with gestational
age.
As a rule of thumb :
• AFI of < 8 implies Oligohydramnios
• AFI of > 25 implies Polyhydramnios

185. Considered a reliable method for
assessing the amniotic fluid
volume on ultrasound.
It is performed by assessing a
maximal depth of amniotic fluid
which is free of umbilical cord.

186. Usually accepted values are
< 2 cm : Oligohydramnios
2 - 8 cm : Normal
but should be taken in the
context of subjective volume
> 8 cm : Polyhydramnios

189. Spina bifida, meningocoele
Encephalocoele
Club foot
Rocker bottom
Osteogenesis imperfecta
Femur length
Bladder
Kdny
Key hole

191. Fountain Geyser
Want to jump to a
bookmark in your video?
Hover over the video and
you’ll be pleasantly surprised.
Did we mention you can add
bookmarks, include fades, and
trim your videos now?

192. What about the beautiful transitions
you’ve been seeing?
Exciting new transitions
They are new too.

193. Deliver Your Presentation
Broadcast and compress for seamless delivery

194. » Show and tell your presentation with
Broadcast Slide Show
» Share your presentation in real-time with
anyone with a browser, directly from
PowerPoint.
» You’ll never have to say, “Next slide, please”
again!
BROADCAST IT

195. Record your presentation with
Create a Video and capture narrations,
animations, media, and much more.
Upload, embed, and share away!

196. ?
But wait…
There’s More!
View your slides from anywhere!

197. » Check out the
PowerPoint Web App
» Access slides wherever you are
Access Anywhere

198. What’s Your Message?POWERPOINT 2010

199. Combined with the BPD, with or without the fetal femur
length, reliable formulas can be used to predict fetal weight.
Level I and Level II Scanning (Screening vs Targeted
Scanning)
Level I (screening) scanning consists of the basic evaluation
listed above. It is usually relatively simple to perform, readily
available, and relatively inexpensive. More detailed scanning
(Level II, or targeted scan) requires higher resolution (more
expensive) equipment and sonographic skills that are more
limited in their availablity and significantly more expensive.
Indications for a Level II scan may include:
Suspicious findings on a Level I scan
History of prior congenital anomaly
Insulin dependent diabetes or other medical problem that
increases the risk of anomaly.
History of seizure disorder, particularly if being treated with
medications known to increase the risk of anomaly.
Teratogen exposure
Elevated MSAFP
Suspected chromosome abnormality
Symmetric IUGR
Fetal arrhythmia
Oligohydramnios, hydramnios
Advanced maternal age