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Obstetric Scanning: Normal Anatomy
Bill Shepherd PhD, RDMS, RVT 2
Objectives 2nd and 3rd Trimester (1)
Documentation of fetal life, # & presentation
Documentation of amniotic fluid volume
Documentation of placental location
Documentation of obstetric age
Documentation of fetal well-being
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Determine Fetal Presentation
SAG ML
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Show Fetal Position
Breech or transverse head right
Sag mll
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Drag inferior to superior
Video Clip 6
Slide Inferior to Superior
Video Clip
2
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Documentation of Life
1. Fetal motion
2. Fetal heart motion
3. Fetal circulation (Doppler)
Video Clip
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Motion 11 weeks / 24 weeks
Video Clips
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M-Mode of the
Fetal Heart
1 2 3 4 5 beats
2 seconds
150 beats /minute
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M-Mode
Video Clips
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Number of Fetuses
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Amniotic Fluid
1. AFI
2. Largest pocket
3. “Eyeball”
3
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Anterior
Posterior
Placental Location
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Lower Uterine
Segment
?
15
Translabial or
Transvaginal Sonography
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Placental Position
LUS - Rule out previa Placenta
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Placenta Previa?
11.0
Video Clips
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Incompetent Cervix
?
4
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33 weeks
Sag ml
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Tropho-tropism:
The preferential proliferation of
trophoblastic villi into regions of better
endometrial blood supply
Atrophy of villi occurs where there is
poorer endometrial blood supply
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Tropho-tropism Explains:
Resolution of placenta previa
Succenturiate lobes of placentas
Marginal & velamentous cord insertions
Vasoprevia
Prolapsed cord
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Placenta Previa: Risk Factors
Advance maternal age
High parity
Prior cesarean section*
Prior elective abortion
Multiple fetuses
Smoking
IVF
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Risk of Placenta Previa
After Caesarian Sections
# of C-Sections Risk of Previa
0 .26%
1 .65%
2 1.8%
3 3.0%
4 10%
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Placenta Previa: False Positives Overfilling of the bladder
Pseudo-
previa
5
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Contraction
Pseudo-previa
6cm
3cm
False Positives Normal
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Previa
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Placental Abruption
Placental abruption is premature separation of
the placenta from the uterus.
Approximately 1% of pregnancies.
15-25% of all perinatal mortality.
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Placental Abruption
Usually pain & vaginal bleeding.
A central abruption may present with pain but no
bleeding.
The recurrent risk is about 1 in 8 pregnancies.
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The 2 types of Placental Abruptions
vaginal bleeding. mass effect.
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Clinical Findings: Placental Abruption
Vaginal Bleeding
Uterine tenderness
Tetanic uterine contraction
Rapid labor
Fetal demise or distress
Disseminated intravascular coagulation
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Fresh Placental Abruption
Placenta
Hemorrhage
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Central Placental
Abruption
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Placental Abruption: False Positives
Fibroids
Marginal Veins
Contractions
Venous Lakes
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Venous lake / gain increased
Video Clip
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Marginal
Veins
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Normal Fetal Anatomy &
Measurements
Head, Neck Spine
Abdominal/ Abdominal wall
Urological, Genital
Skeletal
Cardio-thoracic
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Scanning Planes of the Fetal Head
Sagittal Coronal
Axial
39 11.25
Video Clip
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Transventricular
Choroid Plexus
In lateral ventricle
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Transcerebellar
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Transcerebellar
Thalamus 3rd Vent
Cerebellum Cisterna Magnum
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Transcerebellar View
Cerebellar hemisphere
Cisterna Magna Cavum Septum Pellucidi
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* * Head is ovoid in shape
Symmetrical hemispheres
Sharp edges
Transthalamic
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Tilting transducer for head views
Video Clip 48
Abdominal Views
Abdominal section should be round
Stomach bubble should be seen
Umbilical portion of the PV should be seen
and should be 1/3 of the distance to the
center of the abdomen
A cross-section of the fetal spine showing all
three ossification centers should be seen
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The Fetal Abdominal Circumference
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The Fetal Abdominal
1
2
3
4
5
6
7
1 Stomach
2 Portal vein
3 Spine
4 Aorta
5 Abdominal muscles
6 Spleen
7 Liver
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Normal or Abnormal?
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Why is the stomach so small?
There is nothing to drink…oligohydramnios
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L
R
1
2
3 4
5
Abdomen
1. Umbilical vein
2. Liver
3. Stomach
4. Aorta / IVC
5. Spine
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Subtle Tilting of the Transducer
Video Clip
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Femur
Epiphysis
Video Clip
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4 Chamber Heart
at 14 weeks
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Short Axis
Long Axis
4 Chamber
59 60
Good view for
Heart rate with
M-Mode
11.5
11
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Good 4 Chamber Views @
27weeks 20 weeks
Video Clips 62
45 0
Aorta
R
L
Normal Position of the Fetal Heart
LV RV
RA LA
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Video Clips
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What can be seen in this image?
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kidneys
stm
sp
placenta
amniotic
fluid
umbilical
cord
IVC
aorta
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Rock, slide & drag to see kidneys free of shadow
Video Clips
12
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Urinary Bladder - don’t confuse it with the stomach
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69 Umbilical Cord Insertion in Fetal Abdomen
Video Clip
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Fetal Spine
Sagittal Plane
Transverse Plane
Coronal Plane
Sagittal
Coronal
Transverse
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Anterior Ossification Center
Posterior Ossification Center
Cephalad Caudal
This Sag view is of a fetus
in Breech Position
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Sagittal image of fetal bladder, diaphragm & heart
Fetus is in a vertex position.
What is the placental position?
Anterior
13
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The “Take home Picture”
Rule/ out:
Bossing
Macroglossia
Micrognathia
Nasal bridge
Other
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Diaphragm Biophysical Profile Image
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Diaphragm
Video Clip 76
Cord
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? 1 2
3
4
78 Video Clips
