Trans vaginal sonography in early pregnancy

1. Role of TVS in Early
Pregnancy
Poonam Loomba,M.D.

2. Nothing to disclose

3. Introduction
Advancement in TVS has revolutionised
the management of early pregnancy.
Care providers can utilize this noninvasive
tool for a better understanding of the
embryonic development and thus improve
their clinical as well as counselling skills.

4. Objectives
 1. Highlight embryonic developmental features.
 2. Application of TVS in management of early
pregnancy failure ,ectopic pregnancy and
multiple pregnancies.
 3. Placental pathologies on USG.
 4. Identify and evaluate first trimester markers
of aneuploidy
 5. 3D and 4D USG in first trimester
 6.Markers for Preeclampsia through TVS in
Early pregnancy.

5. Gestation sac
 The first sonographic evidence of
pregnancy is the gestational sac within
the thickened decidua.
 This sac, represents the exocoelomic
fluid of blastocyst surrounded by an
echogenic ring that represents
trophoblasts and decidual reaction.
 The hyperechoic rim should be atleast
2mm thick and its echogenicity should
exceed the myometrial echoes
 With TVS 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%

6. Position of GSAC
 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.

8. DDSIntradecidual Sac Sign
Gestation Sac

9. Identifying yolk sac
 The yolk sac(embryologically secondary
yolk sac) is the first structure seen within
the gestational sac and, when seen,
confirms an intrauterine pregnancy.
 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)


10. Yolk sac
 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

11. Identifying the embryo
 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.

12. Embryo

13. Multiples of 2
 2mm sac 2mm thick
 6mm yolk sac
8mmsac
 2mm embryo ,6 to
12mm g sac
 6mm embryo ,14 to
18 mm g sac
 4w ga
 6wga
 6w ga
 Cardiac activity at
6w ga

14. Viability
 Cardiac activity immediately adjacent to the
yolk sac indicates a live embryo but may
not be seen until the embryo measures 5
mm.(corresponding to GA of 6 .0 to 6.5
weeks and MSD 13-18mm on tvs and MSD
25mm and GA 8 weeks on TAS)
 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.

17. Normal Heart Rate
 5.5 to 6 wks : 1. 100-125/min
2. <100/min
3 100 -115/min
 8wks and above
1. 137-144/min
2 144-159/min
3 140 -160/min

18. Transformation in the structure
of embryo
 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
 Despite the extra amniotic location of yolk
sac initially it remains attatched to the
embryo via an omphalomesentric duct

20. • 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 30mm to
35 mm human appearing embryo is seen

22. Measuring CRL
 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

25. • Upto and including 13 6/7 weeks of gestation, gestational age
assessment based on measurement of the crown–rump length
(CRL) has an accuracy of ± 5–7 days
• 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. Beyond measurements of 84 mm
(corresponding to approximately 14 0/7 weeks of gestation),
the accuracy of the CRL to estimate gestational age
decreases, and in these cases, other second-trimester
biometric parameters should be used for dating

26. Trophoblastic appearance
 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)

27. Abnormal gestation sacs
 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

28. Yolk sac abnormalities
 Enlarged (5 to 6 mm)
seen in IDDM
 or abnormally shaped
(crenellated) yolk sac,
 Calcified
 Echogenic
 Double yolk sac

29. Growth Rate
 MSD increases by 1.13mm/day in
normal gestation and abnormal sac
growth is when MSD fails to grow by at
least .6mm/day

30. CARDIAC ACTIVITY
ABSENT
 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%)

32. Predictors of early pregnancy
loss
 Heart rate-
Persistent bradycardia (heart rate less
than 100BPM before 6.2 weeks and less
than 120 between 6.3 and 7 weeks of
gestation,)
 Bradycardia associated with triploidy
and trisomy 18
 Tachycardia associated with trisomy 13
and turners syndrome

33. Intrauterine blood
 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

34. Subchorionic haemorrhage

35. Small sac size growth delay
 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

36. Amnion abnormailities
 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

37. Role of doppler in predicting
poor pregnancy outcome
 Elevated resistance in uterine and
subchorionic vessels increase abortion
rate
 Increased corpus luteal RI- increased
preg loss

38. Multiple pregnancies

39. DIAGNOSING MULTIPLE
PREGNANCY
 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

41. Chorionicity assessment
(before 10 weeks)
 Number of Yolk Sacs
 Number of GSAC
 Number of amniotic sacs in chorionic
cavity

43. After 10 weeks
 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:MCDA placentation
 Epsilon sign:TCTA placentation
 Membrane thickness:cutoff 2mm

45. Twin Peak or lambda sign

47. Ectopic pregnancy
 Failure to detect an intrauterine
gestational sac by transvaginal
ultrasound when the beta-hCG value
exceeds a discriminatory level (1000 to
2000 mIU/ml) indicates an increased risk
for ectopic pregnancy.
 With a complex adnexal mass or a tubal
ring, the probability of ectopic pregnancy is
high, while a live extrauterine embryo is
diagnostic of an ectopic .

48. USG features of ectopic
pregnancy
 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

53. USG features for ectopic
 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

54. Placental pathologies
 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)

57. Molar pregnancy
 On doppler:high velocity and low
resistance to flow in uterine artery
 Invasive mole:in addition to central
uterine lesion myometrial invasion
present
 Choriocarcinoma:hetrogenous mass
enlarging the uterus due to areas of
necrosis and hemorrhage

58. Screening for chromosomal
anamolies using NT involves:
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 programme that uses
an algorithm based on scientific evidence.
4 Appropriate counselling of the parents.

59. Nuchal Translucency
 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.

60. PROTOCOL FOR
MEASURING NT
 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

61. NT

63. NT
 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.

64. .
 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

65. NTT at 14 wks

66. Causes of increased NT
 Aneuplodies
 Abnormalities of heart and great arteries
 Amnion rupture
 Diaphragmatic hernia
 Skeletal dysplasias
 Achondrogenesis
 Hypoplasia of lymhatics as in Turner
syndrome.
 Anaemia
 Congenital infections

67. First trimester screening
 NT
 Serum free beta hcg
 PAPP-A
 Calculate risk score by adding maternal
age and previous history
 Single cutoff not appropriate.Rather 95th
percentile of CRL

68. NASAL BONE
EVALUATION
 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.

70. PROTOCOL
 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.


71. How to measure NB
 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.

72.  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.

73. DUCTUS VENOSUS FLOW
 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.

74.  Inclusion of ductus venosus 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 ductus venosus 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.

75. PROTOCOL
 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.

76.  The filter should be set at a low frequency (50-
70 Hz) so that the a-wave is not obscured.
 The sweep speed should be high (2-3 cm/s) so
that the waveforms are spread allowing better
assessment of the a-wave.
 When these criteria are satisfied, it is possible to
assess the a-wave and determine qualitatively
whether the flow is positive, absent or reversed.
 The ductus venosus PIV is measured by the
machine after manual tracing of the outline of
the waveform.

77. TRICUSPID FLOW
 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.

78. PROTOCOL
 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.

79. Tricuspid rehurgitation
 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.

86. Diagnosing
anomalies(excluding nt)
 Anencephaly
 Large encephalocoels
 Holoprosencephaly
 Cystic hygroma
 Omphalocoel/gastrochisis(size of
protruding ant abd mass>7mm
and persistence beyond 12weeks)
 Amniotic band syndrome
 Conjoined twins

87. USG Parameters for detection of
downs syndrome in first trimester
 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

88. USG Parameters for detection
of Trisomy 13 in first trimester
 Nuchal translucency
 Nasal bone(absent 40% cases)
 Fetal facial angle(increased 45% cases)
 Ductusvenosus
 Tricuspid regurgitation
 Megacystis(urinary bladder length
>7mm)20%
 Fetal tachycardia

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

90. PREECLAMPSIA
SCREENING
 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.

91. PROTOCOL FOR
MEASURING UTERINE A PI
 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.

92. 3D 4d
 Main advantages are working on the
neurological system,facial
anamolies,anamolies of skeleton esp
limbs,fetal echocardiography
 3DUS is also being considered for
measurement of NT and nasal bone
 Also useful in detailed evaluation of
conjoined twins
 4DUS allows fetal motoral and
behavioural pattern assessment

93. Role of 3d 4d ultrasound in first
trimester
 Allows imaging from volume
sonographic data than
conventional planar data
 Not a substitution but
increasingly useful as a
complementary technique
 3DUS allows better identification
of the anatomic structures and a
detailed fetal anatomy esp in
cases with increase of
chromosomal anomaly risk

94. Factors affecting interpretation
 Imaging results on TVS are operator dependant
 Minimize visual acuity with appropriate magnification
 Myometrial heterogeneity,myomas and IUD can
inhibit early pregnancy structures
 Equipment age ,maintenance and variability
 Multiple gestation or small gestation sacs
 Unusually large sac or growth restricted embryo
Serial ultrasound scans are suggested with follow
up for reassurance and better counselling

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