In this presentation we will discuss First trimester US especially TVS is an integral part for confirmation of intrauterine pregnancy and to rule out ectopic pregnancy. First trimester US helps us in suggesting conceptus viability. First trimester US especially TVS is very efficient in approaching and evaluating the cause of vaginal bleeding.

1. FIRST TRIMESTER ULTRASOUND
Dr. Muhammad Bin Zulfiqar
PGR IV FCPS Services Institute of Medical Sciences / Hospital
radiombz@gmail.com

2. AIMS
• Assessment of gestational age
• Fetal viability and outcomes
• Maternal wellbeing
•

3. INDICATIONS
• Unsure of Dates
• Vaginal Bleeding
• Pelvic Pain
• Exclude an ectopic pregnancy
• Threatened Miscarriage
• Nuchal Translucency (11-13.6 weeks : CRL 45-84mm)
• Maternal past history

4. HISTORY BEFORE US
• Gravidity
• Parity (Miscarriage, Termination of Pregnancy (T.O.P))
• Fertility treatment
• Date of Last Menstrual Period
• Other pregnancy History
• Gynecological History

5. PROBE SELECTIONS
• Curved linear probe approximately 3-7 MHz depending upon
maternal factors
• Transvaginal probe approximately 5-9 MHz (Use of non-latex cover
if required

6. PATIENT PREPARATION
• Emptying of bladder 2 hours before US, then drinking of at least 1
liter of water. Ask patient do not go to the toilet till exam
• For TVS approach empty bladder is needed

7. APPROACH
• Confirm presence of intrauterine gestation
• Look for double decidual reaction.
• Look for no of gestational sacs. If multiple pregnancy
• Confirm number of fetuses
• Number of sacs
• number of placentas
• to determine chorionicity.
• Monochorionic / Monoamniotic(MCMA)
• Monochorionic / Diamniotic(MCDA)
• Dichorionic / Diamniotic (DCDA)
Continued

8. APPROACH
• Confirm heart beat & rate with M-Mode only (Use of Color or
Doppler traces is not recommended in the 1st trimester)
• Measure CRL to calculate gestational age and Estimated Date of
Delivery(EDD).
If too early to see the fetal pole measure the average sac diameter.
Continued

9. APPROACH
• Cervix - assess if closed and measure length between internal and
external os
• Assess placental location and distance from internal os (may lie
close to os at this stage)
• Check for retroplacental hemorrhages, placental masses etc.
• Assess maternal ovaries, adnexa and Pouch Of Douglas (P.O.D)

10. TECHNIQUE
• Uterus – longitudinal and transverse
• Both ovaries
• Adnexa
• Cervix and Pouch-Of-Douglas
• Gestational sac - longitudinal and transverse
Continued

11. TECHNIQUE
• Yolk sac if visible
• Fetal pole
• M mode fetal heart
• Document the normal anatomy. Any pathology found in 2 planes,
including measurements.

12. GESTATIONAL SAC
• The gestational sac(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 surrounding an anechoic centre.
• An ectopic pregnancy will appear the same but it will not be within the
endometrial cavity.
Continued

13. GESTATIONAL SAC
• The GS is not identifiable until approximately 4.5 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.

14. MEAN SAC DIAMETER TVS
• 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

15. YOLK SAC
• 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.

16. YOLK SAC TVS
5 week gestation. Yolk Sac Only seen. The yolk
sac should be visible before a clearly definable
embryonic pole.

18. HEART BEAT
• 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 visualizing a heart beating is the important thing.
• Failure to identify fetal cardiac activity in a fetus whose overall length is greater than 4
mm is an ominous sign.
• Sometimes there is difficulty 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 .

19. HEART RATE M MODE
• 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 bio
effects). Initially the heart rate
may be slow.

20. HEART RATE

21. CROWN RUMP LENGTH (CRL)
• The CRL is a reproducible and accurate method for measuring and dating a
fetus.
• Early ultra sonographers used this term (CRL) because early fetuses also
adopted the sitting in the chair posture in early pregnancy. 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 for most of the first trimester.

22. CROWN RUMP LENGTH (CRL)
• Until 53 days from the LMP, the most caudad portion of the fetal cell mass is
the caudal neuropore, followed by the tail. Only after 53 days is the fetal rump
the most caudal portion of the fetus.
• Until 60 days from the LMP, the most cephalad portion of the fetal cell mass is
initially the rostral neuropore, and later the cervical flexure.
• After 60 days, 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 9.5 weeks gestational age, the fetal CRL grows at a rate of
about 1 mm per day.

23. CRL
• The 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.

24. CROWN RUMP LENGTH (CRL)
• At 10 weeks, visualize
4 jointed limbs, feet and
hands.

25. CROWN RUMP LENGTH (CRL)
• From 12 weeks the basic morphology of
the fetus is visible

26. NUCHAL TRANSLUCENCY
• NUCHAL SONOLUCENCY / FULLNESS / EDEMA
• = skin thickening of posterior neck measured between calvarium
+dorsal skin margins.
• After 13.6 weeks regarded as nuchal fold thickness.
• One inner other outer

27. NUCHAL TRANSLUCENCY
• Considered abnormal when
• > 0.3 mm during 9-13 weeks MA
• >0.5 mm during 14-21 weeks MA
• >0.6 mm during 19-24 weeks MA

28. NUCHAL TRANSLUCENCY
• The Nuchal Translucency is used
to provide a risk assessment for
chromosomal abnormalities,
specifically Trisomy 13,18 and 21
(Down's Syndrome).

29. FETAL LEGS
• The legs are usually crossed at the
ankles. Confirm the presence and
symmetry of the long bones.

30. FETAL LEGS &FEET
• The correct angle the feet to legs
can be confirmed. They should be
at 90 degrees i.e. perpendicular or
Talipes should be suspected.

31. FETAL UPPER LIMB
• The humerus, radius and ulna and the
presence of hands are imaged from 11
weeks.

32. FETAL BRAIN
• 12 week choroids take up most of the
space within the ventricles.

33. MULTIPLE GESTATIONS
• Twins: 2% of all deliveries-12% of NVD.
• Monozygotic 1/250 (1/3 of twins)
• Triplets: 1/802
• Quadruplet: 1/803
• Multiple gestations are HIGH RISK pregnancies.
• The major problems are:
• PRETERM BIRTH
• LOW BIRTH WEIGHT

34. FETAL TWINNING
• Initially twins may be identified as 2 separate gestational sacs (i.e. diamniotic,
dichorionic).
• There may be 2 fetal poles within the same gestational sac (monochorionic).
• It is easier to determine chorionicity earlier in the pregnancy depending on the
chorionicity and amnionicity.
• It is a sad situation when a "vanishing twin" occurs, which is about 20% of twin
pregnancies. In these cases, one of the twins fails to grow and thrive. Instead,
its development arrests and it is reabsorbed, with no evidence at delivery of
the twin pregnancy.

35. MONOCHORIONIC MONOAMNIOTIC TWINS

36. DICHORIONIC DIAMNIOTIC TWINS.

37. TRIPLETS
• Triplets with 2 sacs.
Monoamniotic,
monochorionic twins and
a normal single.

38. COMMON ABNORMALITIES
• Thickened Nuchal Translucency(NL).
• Partial Ovular Detachment.
• Retained products of conception.
• Anembryonic Gestation.
• Gestational trophoblastic disease.
• Miscarriage.
Continued

39. COMMON ABNORMALITIES
• Ectopic Pregnancy.
• Subchorionic hemorrhage.
• Conjoined Twins.
• Antepartum Hemorrhage.
• Check heart beat.
• Check causes of bleeding.

40. THICKENED NUCHAL TRANSLUCENCY
• One of the parameters used in sequential screening (SS) for Down’s syndrome in
first trimester
– SS: Pregnancy associated plasma protein levels, hCG levels, NT thickness
• Measured during 11-13.6 wks gestational age
• Seen on sagittal image as increased subcutaneous non-septated fluid in posterior
fetal neck
• Measurement >3mm usually considered abnormal, however exact cut off
measurements are dependent on maternal age/gestational age
• Detection rate of screening for Down’s Syndrome in first trimester:
– sequential screening with NT: 82-87%
– NT alone: 64-70%.

41. THICKENED NUCHAL TRANSLUCENCY

42. THICKENED NUCHAL TRANSLUCENCY

43. THICKENED NUCHAL TRANSLUCENCY

44. THICKENED NUCHAL TRANSLUCENCY

45. THICKENED NUCHAL TRANSLUCENCY

46. PARTIAL OVULAR DETACHMENT
• The maternal circulation inside the placenta starts peripherally (in the placental
margins) and is associated to physiological oxidative phenomena that may
lead to membranes rupture and formation.
• The abnormal development of such membranes may result in subchorionic
hemorrhage, enhancing the predisposition to an adverse gestational outcome
at the third trimester (PPROM and PTL).
• Such abnormality is common and also denominated as subchorionic
hemorrhage or trophoblastic hematoma, being visualized in more than 18% of
cases of threatened miscarriage.
• The presence of fetal heart activity confers an excellent prognosis. Clinically,
subchorionic hemorrhage may course with vaginal bleeding.

47. PARTIAL OVULAR DETACHMENT
• Sonographic finding of partial
ovulation detachment:
• Heterogeneous crescent shape
lesion is appreciated adjacent to
the gestational sac with gross
debris and shows mild
compression and deformation.
• Fifteen days follow up
demonstrates resolution.

48. PARTIAL OVULAR DETACHMENT
• Sonographic findings of
incomplete decidual fusion.
• Anechoic homogeneous
collection is seen around GS at
7 and 11 week respectively.

49. RETAINED PRODUCTS OF CONCEPTION
• RPOCs are characterized by a thickened, disorganized and
heterogeneous endometrium, with ill-defined mucosal layers and
cavitary line, either with or without the presence of gestational sac.
• Clinically, the women presents abdominal pain and relative vaginal
bleeding(.
• In the presence of an intact gestational sac and closed cervix, the
difficulty in a spontaneous resolution will be higher, requiring
surgical evacuation

50. RETAINED PRODUCTS OF CONCEPTION
• Sonographic finding of RPOCs
as evidences by heterogeneous
ill defined endometrial lined
lesion with cystic changes and
specks of air.

51. RETAINED PRODUCTS OF CONCEPTION

52. RETAINED PRODUCTS OF CONCEPTION
• Transvaginal sonography
without (A) and with (B)
color Doppler imaging in
a case of RPC with
endometrial expansion
(arrows).

53. RETAINED PRODUCTS OF CONCEPTION

54. RETAINED PRODUCTS OF CONCEPTION

55. EARLY EMBRYO DEATH
• Some sonographic findings characterize an embryo death in the first half of
the first trimester in early phases, before the crown-rump length can be
measured.
• The following aspects are highlighted:
• Small, hyperechoic yolk sac,
• Hydropic yolk sac increased in volume with diameter > 7 mm
• Even small amniotic cavity disproportionate to the gestational sac size.
• Before the 9th week, small gestational sac may be associated with aneuploidy.

56. EARLY EMBRYO DEATH
• Sonographic signs of early embryo death.
• A. Intrauterine pregnancy with no sign of embryo, with small, hyperechoic yolk sac.
• B. Monochorionic, diamniotic twin gestation with early death of one of the embryos (vanishing
twin syndrome)

57. EARLY EMBRYO DEATH
• Sonographic signs of early embryo death.
• Small Amniotic cavities

58. EARLY EMBRYO DEATH
• Sonographic signs of early embryo death.
• C. Delayed growth of the gestational sac with disproportionate yolk sac.
• D. Hydropic yolk sac and ruptured amniotic sac with floating branches in the chorionic cavity.

59. EARLY EMBRYO DEATH
Absent Fetal Cardiac Activity

60. EARLY EMBRYO DEATH
Absent FCA

61. ANEMBRYONIC GESTATION
• ANEMBRYONIC PREGNANCY= BLIGHTED OVUM
• Abnormal intrauterine pregnancy with developmental arrest prior
to formation of embryo; may occur as a blighted twin
• Empty gestational sac (>6.5 weeks MA)
• yolk sac identified without embryo:
• Gestational sac small / appropriate / large for dates:
• decrease in gestational sac (GS) size
• GS fails to grow by >0.6 mm/days on serial scans
• Irregular weakly echogenic decidual reaction of <2 mm
• Distorted sac shape

62. ANEMBRYONIC GESTATION
• Transabdominal scan:
• GS size >10 mm of mean diameter without DDS
• GS size >20 mm of mean diameter without yolk sac
• GS size >25 mm of mean diameter without embryo
• Transvaginal scan
• GS size >8 mm of mean diameter without yolk sac
• GS size >16 mm of mean diameter without cardiac activity

63. ANEMBRYONIC GESTATION
• Sonographic signs of Anembryonic gestation.
• A: GS with 12 mm in mean diameter, without yolk sac.
• B: One week later, the GS remains without yolk sac.

64. ANEMBRYONIC GESTATION
BLIGHTED OVUM

65. ANEMBRYONIC GESTATION

66. ANEMBRYONIC GESTATION

67. ANEMBRYONIC GESTATION

68. GESTATIONAL TROPHOBLASTIC DISEASE
• The typical sonographic finding in most of cases of complete hydatidiform mole is a
echogenic, intracavitary solid mass with intermingled, small cystic loci resembling a
"snow storm", corresponding to the vesicles that macroscopically characterize this
condition.
• The higher the gestational age, the larger the vesicles visualized as homogeneous
anechoic images, increasing the method specificity.
• The ultrasonography sensitivity will depend on the gestational age at the moment of
the diagnosis.
• Ultrasonography can detect vesicles with > 2 mm in diameter.
• In early pregnancies with trophoblastic disease, the sonographic method accuracy is
limited, hindering the differentiation of gestational trophoblastic disease from other
conditions involving the endometrial cavity.

69. PARTIAL HYDATIFORM MOLE
• Partial hydatidiform mole offers higher diagnostic difficulty by ultrasonography.
• In a reasonable number of cases, this disease presents as an empty gestational sac
corresponding to anembryonic gestation, or as early embryo death.
• However, two criteria have been described in the literature: gestational sac
transverse/anteroposterior diameter ratio > 1,5 and cystic changes, irregularity of increase in
echogenicity of decidual/placenta or myometrial reaction

70. COMPLETE HYDATIFORM MOLE
• Sonographic signs of
complete Hydatiform mole.
Abdominal and
transvaginal US study
demonstrates echogenic
intracavitary contents with
intermingled tiny cystic
areas.

71. PARTIAL HYDATIFORM MOLE
• Partial Hydatiform mole. Thick,
irregular trophoblast, with
sonographic signs suggesting
anembryonic gestation. H/P study
demonstrated the presence of
molar tissue in the evacuation
material.

72. PARTIAL HYDATIFORM MOLE
• Sonographic signs of partial Hydatiform mole. Focal thickening of the placental
bed with predominance of cystic areas and irregularity. Embryo and embryonic
remains (arrow) can be visualized.

73. COMPLETE HYDATIFORM MOLE
Sonographic signs of arteriovenous malformation associated with complete Hydatiform
mole. Large anechoic homogeneous myometrial lacuna with vascular map showing
fistula pattern and low resistivity flow velocity wave.

74. ECTOPIC PREGNANCY
• Sonographic findings of ectopic pregnancy will vary as a function of the gestational
age and site.
• Classically:
• Tubal ring sign
• Adnexal disorganized mass molded to the adnexa and/or cul de sac
• Solid, organized mass with regular margins mimicking a pediculated myomatous nodule,
• clinically progressing with low β-hCG levels,
• presence of a live extra uterine conceptus.
• Uncommon gestational sites may be observed such as abdominal ectopic pregnancy,
cervical ectopic pregnancy and ectopic pregnancy in a previous Cesarean section
pregnancy.

75. ECTOPIC PREGNANCY
• Sonographic findings of
ectopic pregnancy.
• A: Tubal ring sign
(gestational sac in the
adnexa).
• B: Adenexal mass

76. ECTOPIC PREGNANCY
Sonographic finding of ectopic
pregnancy. Solid, isoechoic
adnexal mass mimicking a
pediculated myomatous nodule

77. ECTOPIC PREGNANCY
• Uncommon sites of ectopic
pregnancy.
• A: GS implanted in cervical
region.
• B: GS implanted on a
previous cesarean section
scar.

78. HETEROTOPIC PREGNANCY

79. CERVICAL ECTOPIC PREGNANCY
• GS within cervix.
• Abnormally low sac
position.
• On color Doppler :
hypertrophic trophoblastic
ring in the cervical region.

80. CERVICAL ECTOPIC PREGNANCY

81. INTERSTITIAL ECTOPIC PREGNANCY
• Eccentric gestational sac: the diagnosis is
suggested by visualization of an
intrauterine GS or decidual reaction located
high in the fundus, that is surrounded by
less than 5 mm of myometrium in all planes.
• Interstitial line sign: an echogenic line from
the mass to the endometrial echo.

82. INTERSTITIAL ECTOPIC
PREGNANCY
• Transvaginal ultrasonography reveals, (a) an eccentrically located round ring-like mass (black
arrow) in the left uterine fundus. Note the thin echogenic endometrial stripe (white arrow)
which extends to the inner margin of this mass, (b) It is incompletely surrounded by
myometrium and is compatible with a corneal pregnancy. This measures approximately 2.6 ×
2.6 cm and (c) demonstrates peripheral blood flow on color Doppler interrogation.

83. CESAREAN SCAR ECTOPIC PREGNANCY
• Empty uterus
• Empty cervical canal
• GS in the anterior part of the lower uterine segment
• Absence of myometrium between the bladder wall and the GS.

84. CESAREAN SCAR ECTOPIC PREGNANCY
• 36-year-old pregnant female presenting with heavy vaginal bleeding for 3 days that slowed
to occasional spotting. Patient had a history of two cesarean sections and was later
diagnosed with ectopic cesarean pregnancy. (a-c) Transabdominal and transvaginal
ultrasonography images reveal (a) a viable gestational sac at the site of previous cesarean
scar (black arrow) with a gestational age of 8 weeks 5 days. (b and c) images show the
gestational sac is in the lower uterine segment, just superior to the cervix and intimately
related to the scar anteriorly (white arrows),
Continued

85. CESAREAN SCAR ECTOPIC PREGNANCY
• MRI d) T2 axial view, (e) T2 sagital view and (f) contrast-enhanced images
demonstrate trophoblastic tissue/developing placenta inferiorly with little or no
surrounding myometrium (white arrow) confirming scar pregnancy There is some
mass effect on the superior aspect of the urinary bladder on the right; however, it
does not appear to invade the bladder wall.

86. SUBCHORIONIC HEMORRHAGE (SCH)
• Occurs when there is perigestational hemorrhage and blood collects between the uterine wall
and the chorionic membrane in pregnancy. It is a frequent cause of first and second trimester
bleeding.
• Epidemiology
• It typically occurs within the first 20 weeks of gestation. If seen in the first 10-14 days of
gestation, they are also sometimes termed implantation bleeds.

87. SUBCHORIONIC HEMORRHAGE (SCH)
• Crescentic collection with elevation of the chorionic membrane
• Depending on the time elapsed since bleeding, the collection will
have variable echotexture
• Acute: hyperechoic and may be difficult to differentiate from adjacent
chorion
• Subacute-chronic: decreasing echogenicity with time
• In almost all cases there is extension of the hematoma towards the
margin of the placenta.

88. SUBCHORIONIC HEMORRHAGE (SCH)

89. First trimester SCH (subchorionic bleed).
SUBCHORIONIC HEMORRHAGE (SCH)

90. SUBCHORIONIC HEMORRHAGE (SCH)

91. SUBCHORIONIC HEMORRHAGE (SCH)

92. SUBCHORIONIC HEMORRHAGE (SCH)

93. SUBCHORIONIC HEMORRHAGE (SCH)

94. SUBCHORIONIC HEMORRHAGE (SCH)

95. SUBCHORIONIC HEMORRHAGE (SCH)

96. CONJOINED TWINS
• Conjoined twins are a rare and complex complication of monozygotic
twinning, which is associated with high perinatal mortality.
• Early prenatal diagnosis of conjoined twins allows better counselling of the
parents regarding the management options, including continuation of
pregnancy with post-natal surgery, termination of pregnancy or selective
fetocide in case of a triplet pregnancy.
• With the introduction of high-resolution and transvaginal ultrasound imaging,
accurate prenatal diagnosis of conjoined twins is possible early in pregnancy.

97. CONJOINED TWINS
• Although first-trimester diagnosis of conjoined twins is feasible, false-positive
cases are common before 10 weeks because, earlier in gestation, fetal
movements are limited and monoamniotic twins may appear conjoined.
• As most parents opt for immediate termination of pregnancy at confirmation
of the diagnosis, there are limited data on the prenatal follow-up of conjoined
twins.
• Detailed analysis of case reports where 3D imaging was used indicates that
this modality does not improve on the diagnosis made by 2D ultrasound.
Overall, very early prenatal diagnosis and first-trimester 3D imaging provide
very little additional practical medical information compared to the 11-14
weeks' ultrasound examination.

98. CONJOINED TWINS
• Images of the conjoined
twins, there are two
heads with conjoined
body.

99. CONJOINED TWINS

100. CONJOINED TWINS
• Conjoined twins.
Ultrasound images of
fetuses joined at the pelvis
and chest, with separate
heads.

101. CONJOINED TWINS
• Three-dimensional sonogram showing the
conjoined twins of the thoraco-
omphalopagus type.

102. FIRST TRIMESTER: BLEEDING/MISCARRIAGE,
MOLAR CHANGES.
• Miscarriage is defined as the loss of a pregnancy prior to the completion of 24
weeks (Age of viability) gestation and the main maternal symptoms are
bleeding and pain. If a fetal HR has been detected, the risk of spontaneous
miscarriage in singletons is 12.2%.

103. FIRST TRIMESTER: BLEEDING/MISCARRIAGE,
MOLAR CHANGES.

104. FIRST TRIMESTER: BLEEDING/MISCARRIAGE,
MOLAR CHANGES.

105. FIRST TRIMESTER: BLEEDING/MISCARRIAGE,
MOLAR CHANGES.

106. TAKE HOME MESSAGE
• First trimester US especially TVS is an integral part for confirmation of
intrauterine pregnancy and to rule out ectopic pregnancy.
• First trimester US helps us in suggesting conceptus viability.
• First trimester US especially TVS is very efficient in approaching and evaluating
the cause of vaginal bleeding.

107. Thank You.