Obstetric Scanning: Normal Anatomy Objectives 2nd and 3rd...

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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

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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”

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Anterior

Posterior

Placental Location

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Lower Uterine

Segment

?

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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

?

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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

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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

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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

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2

3

4

5

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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

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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

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Good view for

Heart rate with

M-Mode

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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

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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

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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

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gshepherd@hvc.rr.com

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My Strangest Case:

8 years after delivery

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Questions?