5. Gestational sac
• After 5 weeks
• Well defined rounded or oval anechoic sac
• Site: within the endometrial cavity near the
uterine fundus
• Surrounded by chorio-decidual reaction > 2
mm.
• Double decidual sac sign (specific)
• MSD by > 1.2 mm /day
6.
7. Yolk Sac
• Spherical cystic structure that within the
gestational sac.
• Should be visualized :
- MSD > 20 mm by TA U/S
- MSD> 8 mm by TV U/S
8.
9. Embryo
• Double bleb sign is the earliest presentation
• Detected earlier by TVUS
• Should be visualized :
- MSD > 25 mm by TA U/S
- MSD> 16 mm by TV U/S
• Measured by Crown rump length (CRL)
14. Fetal measurements
• Mean sac diameter (MSD):
- Used when no embryo
- Average of 3 orthogonal planes
• Crown rump length (CRL):
- Most accurate in 1st trimester (till 12th week).
- Used as a baseline for assessment of fetal
growth for the rest of the pregnancy.
19. Anembryonic sac
- Distorted sac shape with low position.
- Poor chorio-decidual reaction (< 2mm) with
absence of double decidual sac sign.
- Growth < 1 mm/day
- Absence of yolk sac when MSD > 20 mm by
TA U/S or MSD> 8 mm by TV U/S
- Absence of fetal pole when MSD > 25 mm by
TA U/S or MSD> 16 mm by TV U/S
20.
21.
22. Abortion
• Threatened vaginal bleeding yet with live
embryo and closed cervix
• Inevitable open cervix with fetal tissue within
the cervical canal
• Missed GS within the uterus absent cardiac
activity
• Complete No retained products of conception.
• Incomplete retained products of conception.
23. Missed Abortion
• Absent cardiac activity when CRL > 5 mm by
TVUS
• GS within the endometrial cavity
• Closed cervix
31. Sub-chorionic hemorrhage
• Part of the picture of threatened abortion.
• Due to separation of chorion from the
myometrium.
• Before 20 wks
• US appearance varies with age:
- Acute hyper to isoechoic
- Subacute (clotted) hypoechoic
- Chronic (lysis) anechoic
32.
33. Ectopic Pregnancy
• Risk factors PID, IUCD , tubal surgery ,
endometriosis or previous ectopic pregnancy.
• Most common site isthmus of tube
• Other sites ovary , cervix , abdominal cavity
• Presence of intra-uterine pregnancy almost
excludes ectopic pregnancy (1 in 30000)
34. Ectopic Pregnancy
• Sure Signs of ectopic pregnancy:
- Live fetus outside the uterus
- GS with yolk sac outside the uterus
- GS outside the uterus with an echogenic ring
(tubal ring sign)
DD corpus luteum cyst :
- Thin walled
- Within ovary
35.
36.
37. Ectopic pregnancy
• Relative Signs of ectopic pregnancy:
Positive B-HCG +
- No intra-uterine pregnancy (43%)
- Pseudo-gestational sac (no double decidual
sac sign)
- Complex adnexal lesion (other than CL
cyst)(83%)
- Pelvic fluid collection (94 %)
42. Vesicular mole
• Benign form (no myometrial invasion)
• Complete mole no fetus
• Partial mole abnormal triploid fetus
• Classic US appearance (seen in second
trimester):
Uterus filled with innumerable variable sized
cysts (snow-storm appearance)
• Early appearance:
Solid echogenic mass
Anechoic fluid collection ( DD blighted ovum)
43.
44.
45. Invasive Mole
Choriocarcinoma
• Persistent or elevated B-HCG level following
molar evacuation.
• Invasion of myometrium (invasive mole)
• Invasion of myometrium , parametrium and
distant metasteses ( choriocarcionoma)
• US nodules in myometrium (insensitive)
• MRI more sensitive in detection of
myometrial invasion
50. Fetal Measurements
1) Biparietal diameter
• Measured at the level of thalamus
• From outer table of near cranium to the inner table
of far cranium
• Affected by head shape
51. Fetal Measurements
2) Head Circumference
• Measured at same level as BPD
• Outer circumference of the cranium
• Independent of head shape
52.
53. Fetal Measurements
3) Abdominal Circumference
• Measured at the level of intra-hepatic portion of
umblical vein (portal vein)
• Outer circumference of the abdomen
57. Fetal Measurements
• Composite age (average of all parameters) and
estimated fetal weight (EFW) is more accurate than
any single parameter.
• Much more accurate in early pregnancy.
• All subsequent fetal examinations are compared
with 1st examination to assess fetal growth.
58. IUGR
• Diagnosed when EFW is less than the 6th
percentile for gestational age
• Or between 6th and 20th percentile +
oligohydraminos and maternal hypertension
• Normal fetal weigt gain in 3rd trimester is 100-
200 gm week
62. Fetal Doppler
2) Umblical Artery RI
• RI < 0.7
• If > 0.7 impaired feto-placental circulation
• Two arteries + one vein
• Single artery umblical artery ass. with congenital
anomalies
68. Cervical Competence
• Assessed in the beginning of 2nd trimester
• Best assessed by trans-vaginal or trans-labial
US on empty bladder.
• Full bladder falsely elongated the cervical
canal.
• Cervical length > 3 cm
69.
70.
71. Cervical Incompetence
• Cervical length < 25 mm
• Cervical canal diameter > 8 mm
• Funneling of internal os
• Bulging of membranes
75. Placental Grading
(Grade 0)
• Early 2nd trimester
• Uniform moderate echogenicity
• Smooth chorionic plate without indentations
76.
77. Placental Grading
(Grade I )
• Mid 2nd trimester – early 3rd trimester
• Subtle indentations of chorionic plate
• Small, diffuse calcifications randomly
dispersed in placenta
78.
79. Placental Grading
(Grade II )
• Late 3rd trimester
• Larger indentations along chorionic plate
• Larger calcifications
80.
81. Placental Grading
(Grade III )
• 39 wks – post dates
• 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
82.
83. Placenta Previa
• The placenta covers all or part of the internal
os.
• Low lying within 2 cm of os
• 45 % in 1st and 2nd trimester then most of
them resolves.
• Diagnosed in 3rd trimester
• Diagnosed by TVUS or trans-perineal US on an
empty bladder.
84.
85.
86. Placental Abruption
• Ass. With maternal hypertension
• Separation of the placenta from underlying
myometrium retro-placental hematoma
• US appearance varies with age:
- Acute hyper to isoechoic (identified by
placental thickening and disruption of retro-
placental complex)
- Subacute (clotted) hypoechoic
- Chronic (lysis) anechoic
87.
88.
89. Placental Anomalies
• Adherent placenta (acreta):
- If infiltrates myometrium (increta) and serosa
(percreta)
- US loss of retroplacental complex
retroplacental complex within bladder wall
- Best diagnosed by MRI
Uterine bulge- heterogenous placental signal-
intraplacental dark band -focal interruption of
myometrial wall – UB tenting
90.
91.
92.
93. Placental anomalies
• Circumvallate placenta : rolled placental
edges due to smaller chorionic plate (placental
shelf)
• Succenturiate placenta : small accessory lobe
• Bilobed placenta: two equal sized lobes
• Placenta membranacea: thin placenta
covering nearly all the uterine wall
• Chorioangioma: Benign vascular placental
mass… If large high cardiac output HF
94.
95.
96.
97.
98.
99. Amniotic fluid
• AFI (N= 5-20) =
Sum of vertical diameters of the deepest
pockets in the 4 quadrants ( not containing
fetal parts or umblical cord)
• Polyhydraminos :
AFI > 20 , single pocket > 8 , fetus not touching
any uterine wall after 24 wks
• Oligohydraminos:
AFI < 5 , largest pocket < 1 , crowded fetal parts
100.
101.
102. Twin Pregnancy
• Amniocity : no of amniotic sacs
• Chorionicity: no of placentas
• Risk of anomalies:
Monoamniotic > diamniotic monochorionic >
diamniotic dichorionic
• Features of diamniocity:
- Separate placenta
- Different sex
- Chorion extending into the inter-twin membrane
(lambda sign)
103.
104.
105.
106. Twin Transfusion Syndrome
• Shunting through vascular connection in
placenta
• Only if monochorionic
• One fetus IUGR + oligohydraminos
• Other hydrops + polyhdraminos
107.
108. Twin Embolisation syndrome
• Demised Twin
Blood products from dead fetus shunted
through placenta to live fetus
DIC
116. CNS anomalies
2) Presence of Falx:
If absent
absent cortical mantle hydrancepaly
present cortical mantle holoprosencephaly
117.
118.
119.
120. CNS anomalies
3) Trans-thalamic plane:
- Measure BPD , HC
- Detect microcephaly , macrocephaly and
other structural abnormalities
121.
122.
123. CNS anomalies
4) Trans-ventricular plane:
- Dominant feature is choroid plexus within the
ventricular atrium.
- Ventriculomegaly atrial diameter > 10 mm
and separation of corid plexus from
ventricular wall by > 3 mm .
- Most common causes are Chiari II and
aqueductal stenosis.
124.
125.
126. CNS anomalies
5) Trans-cerebellar plane:
- Assess cerebellar hemispheres (hypoplastic in Dandy Walker)
- Assess Cisterna Magna (N= 2-11mm)
If < 2 mm Chiari II (+ small posterior fossa with banana
shaped cerebellum + frontal bossing “ lemon sign” +
hydrocephalus + myelomengiocele)
If > 11mm a)communicating with fourth ventricle
Dandy Walker
b)not communicating with fourth ventricle
Arachnoid cyst or mega cisterna magna
137. CNS anomalies
7) Spina Bifida:
- Outward convergence of vertebral laminae
- Defect in overlying soft tissues
- Protruding sac contain fluid and other neural structures
(menigocele , myelomenigocele)
- Associated with other anomalies e.g. Chiari II
142. Chest Anomalies
( Congenital Diaphragmatic hernia)
• Abdominal contents
within the chest
• Either postero-lateral
(Bochdalek) or antro-
medial (Morgagni)
• US fluid filled
multicystic mass
displacing the heart
+ absence of stomach in
abdomen
143. Chest Anomalies
( Cystic adenomatoid malformation)
• Multi-cystic lesion
• Cysts vary fro
microscopic to 2 cm
144. Chest Anomalies
( Pulmonary Sequestration)
• Mass of sequestrated
lung tissue.
• Extra-lobar type more
frequently detected by
fetal US
• US Homogenous
echogenic solid lung
mass displacing the
mediastinum
145. Fetal Heart Assessment
• Assessed in four chamber view on axial scan
• Ventricles are nearly equal in size
• Ventricles smaller than atria
• Apex is directed to the left at 45
• Any abnormality fetal echo is requested
155. Bladder
• Should be observed to
fill and empty.
• Related to the amniotic
fluid index
• PUV keyhole sign +
hydronephrosis
156. Abdominal Herniations
Gastroschisis
- On the side of umblical
cord
- No covering
membranes
- Normal cord insertion
- Isolated
Omphalocele
- Midline (at umblicus)
- Covered by membranes
- The cord inserts in it.
- Associated anomalies
are common
157.
158.
159. Skeletal Anomalies
US findings ass. with skeletal dysplasia:
- Extremity bone shortening (short femur)
- Fractures
- Bowing
- Demineralization
- Small thorax
