Role of trrans vaginal sonography in early pregnancy as to detect abnormal gestations,early detection of aneuploidies.Study markers for trisomies 13,18,21

1. Poonam Loomba ,M.D.

2. The main goal of a fetal ultrasound scan is to
provide accurate information which will facilitate
the delivery of optimized antenatal care with the
best possible outcomes for mother and fetus.
First trimester’ here refers to a stage of pregnancy
starting from the time at which viability can be
confirmed (i.e. presence of a gestational sac in the
uterine cavity with an embryo demonstrating
cardiac activity) up to 13 + 6 weeks of gestation.

4. We use the term ‘embryo’
for before 10 weeks and ‘fetus’ thereafter, to
reflect the fact that after 10 weeks of gestation
organogenesis is essentially complete and
further development involves predominantly
fetal growth and organ maturation.

5.  It is advisable to offer the first ultrasound scan
when gestational age is thought to be between
11 and 13 + 6 weeks’ gestation.
 Before starting the examination, a healthcare
provider should counsel the woman/couple
regarding the potential benefits and limitations
of the first-trimester ultrasound scan.

6.  B-mode and M-mode prenatal ultrasonography, due to its
limited acoustic output, appears to be safe for all stages of
pregnancy .
 Doppler ultrasound is however, associated with greater
energy output and therefore more potential bioeffects,
especially when applied to a small region of interest.
 Doppler examinations should only be used in the first
trimester, therefore, if clinically indicated.

7. The MSD is the average of
the three orthogonal
measurements of the fluid-
filled space within the
gestational sac.
The size threshold for sac
detection is 2 to 3mm
corresponding to between
4 weeks 1 day to 4 weeks 3
days gestation
The loss rate at this stage is
11.5%

8.  Normal position is in the mid to
upper uterus
 Intradecidual sign :as the sac
implants into the decidualized
endometrium it should be
adjacent to linear central cavity
echo complex without
displacing this hyperechoic
anatomic landmark
 Double decidual sac sign: as
the sac enlarges it impresses
and deforms the central cavity
echo complex giving
appearance of DDSS .Visible
when MSD is 10mm.
DDS

9. The use of terms such as an ‘apparently empty’ sac,
the Double decidual ring’ or even ‘pseudosac’ do
not accurately confirm or refute the presence of an
intrauterine pregnancy.
In an asymptomatic patient, it is advisable to wait
until the embryo becomes visible within the
intrauterine sac as this confirms that the ‘sac’ is
indeed a gestational sac.
pregnancy.

10.  Transvaginal sonographic
diagnosis of a blighted ovum is
certain when the mean
gestational sac diameter exceeds
8mm without a yolk sac or
when the mean gestational sac
diameter exceeds 16 mm
without an embryo
 Transabdominally, a
gestational sac greater than 20
mm without a yolk sac or 25
mm without an embryo is
diagnostic of a blighted ovum

11.  Distorted sac shape
 thin<2mm
 weakly echogenic
 and irregular choriodecidual reaction
 Absence of DDSC when MSD>10 mm
 Presence of chorionic bump(irregular convex
bulge arising from choriodecidual surface and
protruding into GSAC)

12.  A small sac size relative to the embryo
(difference of less than 5 mm between
gestational sac and crown/rump length)
indicates early oligohydramnios and increased
rate of abortion

13.  The yolk sac is seen by
transvaginal ultrasound
when the mean
gestational sac
diameter is 5 to 6
mm(5 weeks) and
should always be
visualized when the
mean gestational sac
diameter is greater than
or equal to 8 mm.(5.5
weeks)

14.  Yolk sac is normally spherical in shape with a
well defined echogenic periphery and a
sonoluscent centre
 Size:steadily increases from 5 to 10 weeks to a
max of 5 to 6mm(corresp to CRL 30 to 45 mm)
 As GA advances it seperates and detatches
from the embryo,diameter decreases and
becomes irregular
 Not visualized on tvs by end of first trimester

15.  Enlarged (5 to 6 mm) seen in
IDDM
 or abnormally shaped
(crenellated) yolk sac,
 Calcified
 Echogenic
 Double yolk sac

16.  The embryo can be identified
by transvaginal ultrasound
when as small as 1 to 2 mm
in length(corresponding to 5
to 6 weeks GA and MSD
between 5 to 12mm)
 Its seen as a focal area of
thickening along the
periphery of yolk sac
 At 5 to 7 weeks, both the
embryo and gestational sac
should grow by 1 mm daily.

18. Cardiac activity is often evident when the embryo
measures 2 mm or more but is not evident in around
5–10% of viable embryos measuring between 2 to 4
mm.
From 5.5 to 6.5 weeks, an embryonic heart rate of less
than 100 beats per minute is normal.
During the following 3 weeks, there is a rapid
increase up to 180 beats per minute.

20.  Sonographic diagnosis of embryonic demise
can be made when there is no cardiac activity
in an embryo greater than 5mm by
transvaginal ultrasound or 9 mm by
abdominal ultrasound
 (If cardiac activity is present in at 8 weeks the
risk of loss is only 2 to 3%)

22.  Heart rate-
Persistent bradycardia (heart rate less than
100BPM at 6.5 weeks and less than 120 between
6.5 and 7 weeks of gestation,)
 Bradycardia associated with triploidy and
trisomy 18
 Tachycardia associated with trisomy 13 and
turners syndrome

23.  During 6th week,with
ventral folding of cranial
and caudal ends of
embryo it changes shape
from a flat disc to a 3d C
shaped structure
 Brain and head become
prominent as rostral
neuropore closes and
caudal neuropore
elongates and curves into
a tail

24. • By 7th to 8th week limb
buds evolve
• By 9th week extremities
protrude ventrally trunk
elongates and straightens
and midgut herniation
into umbilical cord
becomes more prominent
• By 10 th week at embryo
length 30 mm to 35 mm
human appearing
embryo is seen

25.  Pregnant women should be offered an early
ultrasound scan between 10 + 0 and 13 + 6
weeks to establish accurate gestational age.
(Grade A recommendation)
 In the first trimester, many parameters are
related closely to gestational age, but CRL
appears to be the most precise allowing
accurate determination of the day of
conception, to within 5 days either way in 95%
of cases.

26. If pregnancy resulted from assisted
reproductive technology (ART), the
ART-derived gestational age should
be used to assign the estimated due
date (EDD). For instance, the EDD for
a pregnancy that resulted from in
vitro fertilization should be assigned
using the age of the embryo and the
date of transfer.

27.  CRL measurements can be carried out transabdominally or
transvaginally.
 A midline sagittal section of the whole embryo or fetus should
be obtained, ideally with the embryo or fetus oriented
horizontally on the screen.
 An image should be magnified sufficiently to fill most of the
width of the ultrasound screen, so that the measurement line
between crown and rump is at about 90 degrees to the
ultrasound beam
 Electronic linear calipers should be used to measure the fetus in a
neutral position (i.e. neither flexed nor hyperextended. )
 Care must be taken to avoid inclusion of structures such as the
yolk sac.
 In order to ensure that the fetus is not flexed, amniotic fluid
should
be visible between the fetal chin and chest

30. • The measurement used for dating should be the mean of three
discrete CRL measurements when possible and should be
obtained in a true midsagittal plane, with the genital tubercle
and fetal spine longitudinally in view and the maximum
length from cranium to caudal rump measured as a straight
line
• Mean sac diameter measurements are not recommended for
estimating the due date.
• It is recommended that CRL measurement should
be used to determine gestational age unless it is above 84
mm; after this stage, HC can be used, as it becomes slightly
more precise than is BPD. (GOOD PRACTICE POINT)

33. Note true axial view
through head and
central position
of third ventricle and
midline structures (T
indicates third
ventricle and
thalamus). Head
circumference would
also be measured in
this plane.

34. Normal choroid plexuses
(C) and midline falx and
interhemispheric fissure
(arrows).
Note that choroid plexuses
extend from the medial to
the lateral border of the
posterior horn.
Lateral walls of anterior
horns are indicated by
arrowheads.

35. Doppler can be helpful in confirming the
presenceof two umbilical arteries, but this is
not part of the routine
assessment.

36. Axial section of the fetal thorax at the level of the
four-chamber view of the heart, with the cardiac apex pointing to
the left (L). Note atria and ventricles are symmetrical on either side
of the septum (arrow). Lung fields are of homogeneous
Echogenicity and symmetrical. Aorta is just to left side of spine (S).

37. Fetal spine. Intact skin is visible posterior to the vertebrae from neck to sacrum in
a true median view. Note vertebral bodies show ossification, but neural arches,
which are still cartilaginous, are isoechoic or hypoechoic.

40.  Needs high standard of knowledge and
expertise.
 The machine should have a good resolution
,video loop function .
 In 95% of cases it can be measured by TAS ..in
rest by TVS.
 Minimum 80-100 scans needed for good
results.

41.  Fetus in neutral position.
 Mid sagittal plane with face
and chest occupying full
screen
 11 to 13+ 6 weeks
 The magnification should be
such that each increment in
the distance between calipers
should be 0.1mm

42.  Measurements should be taken with the inner border
of the horizontal line of the callipers placed ON the line
that defines the nuchal translucency thickness - the
crossbar of the calliper should be such that it is hardly
visible as it merges with the white line of the border,
not in the nuchal fluid.
 In magnifying the image (pre or post freeze zoom) it is
important to turn the gain down. This avoids the
mistake of placing the calliper on the fuzzy edge of the
line which causes an underestimate of the nuchal
measurement.
 During the scan more than one measurement must be
taken and the maximum one that meets all the above
criteria should be recorded in the database.

44. .
 The umbilical cord may be round the fetal
neck in about 5% to 10% of cases and this
finding may produce a falsely increased
NT.
 In such cases, the measurements of NT
above and below the cord are different
and, in the calculation of risk, it is more
appropriate to use the lowest of the two
measurements

45.  Aneuplodies
 Abnormalities of heart and great arteries
 Amnion rupture
 Diaphragmatic hernia
 Skeletal dysplasias
 Achondrogenesis
 Hypoplasia of lymhatics as in Turner
syndrome.
 Anaemia
 Congenital infections

46. 1 . Carrying out the ultrasound examination by
appropriately trained sonographers.
2.Measurement of maternal serum free β-hCG and
PAPP-A by laboratories that can demonstrate good
quality assurance performance.
3. A risk calculation program that uses an
algorithm based on scientific evidence.
4 Appropriate counselling of the parents.

47.  Nuchal translucency
 Nasal bone(absent 69% cases)
 FMF angle
 Ductus venosus flow velocity waveform
 Tricuspid regurgitation
 Fetal heart rate(tachycardia)
 Underdevelopment of maxilla(seen in 50% cases)
 Short ear length
 Short femur and humerus during 11-16 weeks at 6
day scan window

48.  Nuchal translucency
 Nasal bone(absent 40% cases)
 Fetal facial angle(increased 45% cases)
 Ductusvenosus
 Tricuspid regurgitation
 Megacystis(urinary bladder length
>7mm)20%
 Fetal tachycardia

49.  Trisomy 18: absent nasal bone 50% cases,single
umbilical artery(7 fold ),fetal bradycardia
 Turners syndrome:choroid plexus cyst(75%
cases)

50.  In a high proportion of fetuses with trisomy 21 and
other chromosomal abnormalities the nasal bone is
hypoplastic or not visible at 11-13 weeks' gestation.
 Assessment of the nasal bone at 11-13 weeks
improves the performance of combined screening
for trisomy 21 by maternal age, fetal nuchal
translucency (NT) and serum biochemistry.
 The difficulty is when the gestation is 11 weeks or
the beginning of the 12th week and the nasal bone
is absent but the NT, the other ultrasound markers
and the serum biochemistry are normal.

53.  The gestational period must be 11 to 13 weeks and six
days.
 The magnification of the image should be such that
the fetal head and thorax occupy the whole image.
 A mid-sagittal view of the face should be obtained.
 This is defined by the presence of the echogenic tip of
the nose and rectangular shape of the palate
anteriorly, the translucent diencephalon in the centre
and the nuchal membrane posteriorly.
 Minor deviations from the exact midline plane would
cause non-visualization of the tip of the nose and
visibility of the zygomatic process of the maxilla.


54.  The ultrasound transducer should be held parallel to the
direction of the nose and should be gently tilted from side to
side to ensure that the nasal bone is seen separate from the
nasal skin.
 The echogenicity of the nasal bone should be greater that
the skin overlying it.
 In this respect, the correct view of the nasal bone should
demonstrate three distinct lines: the first two lines, which
are proximal to the forehead, are horizontal and parallel to
each other, resembling an "equal sign".
 The top line represents the skin and bottom one, which is
thicker and more echogenic than the overlying skin,
represents the nasal bone.
 A third line, almost in continuity with the skin, but at a
higher level, represents the tip of the nose.

55.  When the nasal bone line appears as a thin line,
less echogenic than the overlying skin, it suggests
that the nasal bone is not yet ossified, and it is
therefore classified as being absent.

56.  Three-dimensional (3D) and 4D ultrasound are
not currently used for routine first-trimester fetal
anatomical evaluation, as their resolution is not
yet as good as that of 2D ultrasound. In expert
hands, these methods may be helpful in
evaluation of abnormalities, especially those of
surface anatomy.

59.  Presence of subchorionic blood increases the
abortion rate to 8 %
 Various sites are:retroplacental
 Preplacental
 Marginal
 Subamniotic
 On USG it appears initially as a hypoechoic
area adjacent to GSAC which later becomes
hypo/anechoic

60. Subchorionic haemorrhage

61.  Membrane is easily visualized
 Thickness and echogenicity similar to yolk sac
 Enlarged yolk sac in relation to CRL(normal
preg diff 1mm in CRL and amniotic cavity
diameter)
 Double bleb sign

62.  Elevated resistance in uterine and subchorionic
vessels increase abortion rate
 Increased corpus luteal RI- increased preg loss

63.  Always begin a scan with a complete imaging
sweep of the uterus and count the number of
fetus, determine their presentation,document
their site and chorionicity
 First trimester evaluation is the best time to
determine the chorionicity in multiple
gestation

64.  Number of Yolk Sacs
 Number of GSAC
 Number of amniotic sacs in chorionic cavity

65.  Sex discordance
 No of distinct placenta
 Twin peak/lambda sign-results from
echodense chorionic villi between the two
layers of chorion at its origin from the
placenta.(100% PPV for DC placentation)
 T sign:MCMA placentation
 Epsilon sign:TCTA placentation
 Membrane thickness:cutoff 2mm

69.  The sonographic appearance of
an ectopic is varied ranging
from
 simple adnexal cyst,
 complex adnexal mass,
tubal ring, (ring on fire app)
 free fluid in the adnexa-cul de
sac,
 a live extrauterine fetus,
 or an empty uterus with no
other sonographic findings

71.  Negative sonographic signs-
intrauterine pregnancy
 False negative sonographic sign-
intrauterine Gsac
 Indirect positive sign-empty
uterus and the discriminatory
zone and free pelvic and
abdominal fluid
 Direct positive sign-adnexal
pregnancy,tubal or adnexal
ring,complex or solid mass

72.  Echo rich trophoblastic
tissue-diffuse small
cystic structures
without gestational
components.
 Snowstorm appearance
 Theca lutein cysts in
adnexal region(soap
bubble or spoke wheel
app of ovaries)

73.  Echo rich trophoblastic tissue-diffuse small
cystic structures without gestational
components.
 Snowstorm appearance
 Theca lutein cysts in adnexal region(soap
bubble or spoke wheel app of ovaries)

75.  Anencephaly
 Large encephalocoels
 Holoprosencephaly
 Cystic hygroma
 Omphalocoel/gastrochisis(size of
protruding ant abd mass>7mm
and persistence beyond 12weeks)
 Amniotic band syndrome
 Conjoined twins

76.  Increased impedance to flow in the fetal ductus
venosus at 11-13 weeks’ gestation, is associated
fetal aneuploidies, cardiac defects and other
adverse pregnancy outcomes.
 Most studies examining ductus venosus flow have
classified the waveforms as normal, when the a-
wave observed during atrial contraction is
positive, or abnormal, when the a-wave is absent
or reversed.
 The preferred alternative in the estimation of
patient-specific risks for pregnancy complications
is measurement of the pulsatility index for veins
(PIV) as a continuous variable.

77.  The gestational period must be 11 to 13 weeks and
six days.
 The examination should be undertaken during fetal
quiescence.
 The magnification of the image should be such that
the fetal thorax and abdomen occupy the whole
image.
 A right ventral mid-sagittal view of the fetal trunk
should be obtained and color flow mapping should
be undertaken to demonstrate the umbilical vein,
ductus venosus and fetal heart.
 The pulsed Doppler sample volume should be small
(0.5-1.0 mm) to avoid contamination from the
adjacent veins, and it should be placed in the
yellowish aliasing area.
 The insonation angle should be less than 30 degrees.

78.  Tricuspid regurgitation at 11-13 weeks’ gestation is a
common finding in fetuses with trisomies 21, 18 and 13 and
in those with major cardiac defects.
 Tricuspid regurgitation is found in about 1% of euploid
fetuses, in 55% of fetuses with trisomy 21 and in one third of
fetuses with trisomy 18 and trisomy 13.
 Inclusion of tricuspid blood flow in first-trimester
combined screening improves the detection rate for trisomy
21 from about 90% to 95% for a false positive rate of 3%.
 Assessment of tricuspid flow need not be carried out in all
pregnancies undergoing routine first-trimester combined
screening. Such examination could be reserved for the 15%
of the total population with an intermediate risk (between 1
in 51 and 1 in 1000) after combined testing.

79.  The gestational period must be 11 to 13
weeks and six days.
 The magnification of the image should
be such that the fetal thorax occupies most
of the image.
 An apical four-chamber view of the fetal
heart should be obtained.
 A pulsed-wave Doppler sample volume
of 2.0 to 3.0 mm should be positioned
across the tricuspid valve so that the angle
to the direction of flow is less than 30
degrees from the direction of the inter-
ventricular septum.

80.  Tricuspid regurgitation is diagnosed if it
is found during at least half of the systole
and with a velocity of over 60 cm/s, since
aortic or pulmonary arterial blood flow at
this gestation can produce a maximum
velocity of 50 cm/s.
 The sweep speed should be high (2-3
cm/s) so that the waveforms are widely
spread for better assessment.
 The tricuspid valve could be insufficient
in one or more of its three cusps, and
therefore the sample volume should be
placed across the valve at least three times,
in an attempt to interrogate the complete
valve.

81.  There is now evidence that a combination of
maternal demographic characteristics, including
medical and obstetric history, uterine artery
pulsatility index (PI), mean arterial pressure
(MAP) and maternal serum pregnancy associated
plasma protein-A (PAPP-A) and placental growth
factor (PlGF) at 11-13 weeks' gestation can identify
a high proportion of pregnancies at high-risk for
PE.
 Such early identification of the high-risk group for
PE is important because the risk may be
substantially reduced by the prophylactic use of
low-dose aspirin starting from 11-13 weeks.

82.  The gestational age must be between 11
weeks and 13 weeks and six days.
 Sagittal section of the uterus must be
obtained and the cervical canal and internal
cervical os identified.
 Subsequently, the transducer must be gently
tilted from side to side and then colour flow
mapping should be used to identify each
uterine artery along the side of the cervix and
uterus at the level of the internal os.
 Pulsed wave Doppler should be used with
the sampling gate set at 2 mm to cover the
whole vessel and ensuring that the angle of
insonation is less than 30º. When three similar
consecutive waveforms are obtained the PI
must be measured and the mean PI of the left
and right arteries be calculated.

83. Special attention should be given to patients with a
prior Cesarean section, who may be predisposed to
scar pregnancy or placenta accreta, with significant
complications.
The uterine isthmus at the site of the Cesarean section
scar should be scrutinized. In suspected cases,
consideration should be given to prompt specialist
referral for further evaluation and management.
Although the issue of routine scans in women with a
history of Cesarean section may be raised in the future
There is currently insufficient evidence to support
inclusion of such a policy in routine practice.

85.  Gynecological pathology, both benign and
malignant, may be detected during any first-
trimester scan. Abnormalities of uterine shape,
such as uterine septa and bicornuate uteri,
should be described. The adnexa should be
surveyed for abnormalities and masses.

86. Through our efforts at continued learning and improvising technologies
we can thus help build happy families