2nd and 3rd Trimester OB Protocol
Protocol



Protocol will vary with patient age and fetal position
The goal of the exam is to image each structure in the protocol
The protocol is divided up into sections
 It is highly recommended that you complete each image in the applicable section before moving to
the next section when possible.
Placenta Comp Images- Heart Rate, Uterine Cervix, Ovaries, Adnexa, Placenta, and Fluid
Structure/
Order
Scan
Plane
Label
Landmarks Identified

Uterus/
Fetus
Uterine
Cervix
Adnexa
TX
NO IMAGE-SCAN
THROUGH
TX
HEART RATE

TX
HEART RATE

Sagittal
CERVIX ML
Sagittal
CERVIX ML







Sagittal
FETAL LIE


Sagittal
Sagittal
ADNEXA SAG RT
ADNEXA SAG LT
PLACENTA
SAG INF
PLACENTA
SAG MID
PLACENTA
SAG SUP
Q1









Q2

Q3

Sagittal
Placenta
Sagittal
Sagittal
Amniotic
Fluid Index
(volume)
Q1+Q2+Q3
+Q4= AFI
*Structures
seen in each
pocket will
vary
Sagittal
Sagittal
Sagittal

Sagittal
Q4
Begin at cervix, move superiorly out of uterine fundus
o Identify the fetus within the uterus
o Identify number of fetuses
o Identify fetal lie
o Determine the right and left sides of the fetus
Fetal heart and chest
o Enlarge image of heart and document heart rate
with M-mode or Spectral Doppler
Fetal heart and chest
o Enlarge image of heart and document heart rate
with a cine-loop
Vaginal Canal
Cervix
Amniotic Sac
Vaginal Canal
Cervix
Amniotic Sac
Measure Cervical Length
o External os to internal os
Document presenting fetal structure
Cervix
o Indicate Breech or Vertex in annotation
RT Adnexa include ovary if possible
LT Adnexa include ovary if possible
Placenta closest to Cervix
Retroplacental complex
Placenta Mid- include cord insertion
Retroplacental complex
Placenta- superior portion
Retroplacental complex
Measure largest vertical pocket clear of fetal components
from Anterior to Posterior
Measure largest vertical pocket clear of fetal components
from Anterior to Posterior
Measure largest vertical pocket clear of fetal components
from Anterior to Posterior
Measure largest vertical pocket clear of fetal components
from Anterior to Posterior
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol
Fetal Measurements
Structure/
Order
Scan
Plane
Label

Fetal
Measurements
BPD



HC

Trans
Axial
CEREBELLUM


CISTERNA
MAGNA


NUCHAL FOLD
Abdomen
TX
Long
Bone
AC







FL


Long
Bone
HL
Landmarks Identified
Cavum septum pellucidum, IHF, Thalami and Parietal
bones
Measurement technique
Place calipers on the outside of the closet parietal
bone to the inside of the farthest parietal bone
Cavum septum pellucidum, IHF, Thalami and Parietal
bones
Measurement technique
o Place calipers outside to outside of the parietal
bones
o Open the calipers with an ellipse that surrounds
the fetal skull
IHF, Cerebral Peduncles, Cerebellum, Cisterna
Magna, and Nuchal Fold
Measurement technique
o Place calipers on the outside of the lateral wall to
the outside of the opposite lateral wall
IHF, Cerebral Peduncles, Cerebellum, Cisterna
Magna, and Nuchal Fold
Measurement technique
o Place calipers at the level of the mid posterior
wall of the cerebellum to the inside of occipital
bone
IHF, Cerebral Peduncles, Cerebellum, Cisterna
Magna, and Nuchal Fold
Measurement technique
o Place calipers at the level of the mid posterior
wall of the cerebellum from the outside of
occiptal bone to outside skin line
Umbilical vein/portal vein junction
3 points of the spine
Symmetrical ribs
Measurement technique
o Place calipers on outside of skin line directly
behind spine and in front of abdomen.
o Open calipers to form an ellipse around
abdomen including the skin line
Femur bone with distal or end shadowing
Measurement technique
o Place calipers from end to end on the femur Do not include epiphysis point
o Calipers should dissect the middle of the bone
Humerus bone with distal or end shadowing
Measurement technique
o Place calipers from end to end on the
humerus-Do not include epiphysis point
o Calipers should dissect the middle of the bone
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol
Fetal Head and Face Structures
Organ/
Order
Scan Plane
Label
Landmarks Identified
Fetal Head
Coronal
CHP


IHF
Choroid Plexus within ventricle
o Try to get both in one image, if not do
separately (in axial plane)
Fetal Head
Transaxial
VENTRICLES
(indicate
RT & LT)


IHF
Ventricles



IHF
Ventricle
Measurement Technique
o Posterior ventricle
o Measure internally lateral to medial at glomus
FACE


Orbits
Mandible
LENS


Orbits
Echogenic lens (can be in transaxial plane)
NOSE AND LIPS


Nostrils
Upper lip
PROFILE

Forehead, nose, extended chin and neck
Fetal
Head
VENTRICLES
(indicate
RT & LT)
Fetal Face
Face
Coronal
Face
Midline
Sagittal
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol
Organ/
Order
Fetal Thorax, Abdomen and Pelvic Structures
Scan Plane
Label
Landmarks Identified
Sagittal
Thorax/
Abdomen
Sagittal
Stomach
Transverse
Transverse
Kidneys
DIAPHRAGM
RT



RT lung
Diaphragm
Liver
DIAPHRAGM
LT



LT lung
Diaphragm
Stomach


Stomach
Transverse spine



Transverse spine
Right kidney
Left kidney
Left Sagittal Kidney (can be taken in coronal)
Measurement technique
o Superior to inferior border
Left Sagittal Kidney (can be taken in coronal)
Measurement technique
o Superior to inferior border
Transverse spine
Umbilical cord insertion into abdomen
Abdominal skin line
Umbilical cord projecting from abdomen
STOMACH
KIDNEYS
Sagittal
RK SAG


Sagittal
LK SAG


Transverse
CI
Transverse
CORD
Umbilical
Cord





Free floating loop of umbilical cord demonstrating
3VC



Iliac wings
Bladder
Color Doppler around bladder
Bladder/
Cord
Transverse
3VC
Bladder
Transverse
BLADDER


Iliac wings
Bladder
GENDER

(identify
male or
female)

Male
o Scrotum and penis
Female
o Labia
Gender
Transverse
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol
Fetal Spine and Extremities
Organ/
Order
Scan Plane
Label
Landmarks Identified
CSP SAG

Skull, cervical spine, and upper thorax
o Sagittal view not available coronal is
acceptable, label accordingly
Sagittal
TSP SAG

Distal neck, thorax, and upper abdomen
o Sagittal view not available coronal is
acceptable, label accordingly
Sagittal
LSP SAG

Lower abdomen to lower point of LSP
o Sagittal view not available coronal is
acceptable, label accordingly
Transverse
CSP TX

Spine up-just below skull, skin line
Transverse
TSP TX

Spine up-mid thorax, rib, skin line
LS-SP TX

Spine up-iliac wings, skin line
RT HUMERUS

Shoulder, humerus and elbow


Elbow, ulna, radius and wrist
Wrist and fingers (open and closed)
LT HUMERUS

Shoulder, humerus and elbow
Longitudinal
LT ULNA/RADIUS

Elbow, ulna, radius and wrist connections
Longitudinal
LT HAND

Wrist and fingers (open and closed)
Longitudinal
RT FEMUR

Femur and knee
Lower Extremity Longitudinal
RT TIB/FIB

Knee, tibia, fibula and ankle
o FRONTAL View
Coronal
RT FOOT


Foot
Toes
Longitudinal
LT FEMUR

Femur and knee
LT TIB/FIB

Knee, tibia, fibula and ankle
o FRONTAL View
LT FOOT


Foot
Toes
Sagittal
Spine
Transverse
Longitudinal
Longitudinal RT ULNA/RADIUS
Longitudinal
RT HAND
Upper Extremity Longitudinal
Longitudinal
Coronal
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol

Fetal Heart
Fetal heart images will vary from site to site. All students are responsible for completing a sweep
through the heart to determine situs, connection and recognize views
Organ/Order





Landmarks Identified
Right and left atrium
Foramen Ovale
Right and left ventricle
Tricuspid and Mitral Valves
Spine
(IVS Vertical)





Right and left atrium
Foramen Ovale
Right and left ventricle
Tricuspid and Mitral Valves
Spine
Superior Vena
Cava & Inferior
Vena Cava
Long axis
Sagittal fetal
chest



Inferior vena cava
Right atrium
Superior vena cava
Left Ventricular
Outflow Tract
Long Axis
Transverse
fetal chest



Left ventricle
Aortic valve
Aortic root



Proximal aorta
3 branches-innominate, left common carotid artery
& left subclavian
Thoracic aorta



Right ventricle
Pulmonary valve
Pulmonary trunk












RT ventricle
Pulmonary valve
RT pulmonary artery
LT pulmonary artery
Aorta
Aortic valve
Pulmonary trunk
Ductus arteriosus
Thoracic aorta
AO
SVC
DA
Subcostal
4 Chamber
View
Apical
4 Chamber
View
Aortic Arch
Right
Ventricular
Outflow Tract
Right
Ventricular
Outflow Tract
Ductus
Arteriosus Arch
3 Vessel View
Scan Plane
Transverse
fetal chest
(IVS
horizontal)
Transverse
fetal chest
Sagittal Fetal
Chest
Long Axis
Transverse
Fetal Chest
Short Axis
Transverse
Fetal Chest
Label
4CH
SUBCOSTAL
4CH
APICAL
SVC/IVC
LVOT
AA
RVOT
RVOT
SHORT
Sagittal Fetal
Chest
DA
Transverse
Fetal Chest
3 VESSEL
VIEW
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx
2nd and 3rd Trimester OB Protocol
Normal Measurement Ranges
Structure
Amniotic Fluid
Volume
Sum of 4 amniotic
fluid measurements
Area of Interest
Divide the
uterus into 4
quadrants and
measure the
largest vertical
pocket of
amniotic fluid in
each quadrant
Plane
Sagittal
Measurement
Greater than

20cm-abnormal 
Less than 5cmabnormal

*measurement
may vary per site


Amniotic Fluid
Largest Vertical
Pocket
Single
Sagittal
Greater than

10cm-Abnormal
Less than 2cm- 
Abnormal
*measurement
may vary per site
Comments
Patient should be supine
With the probe in the sagittal
position, locate the largest
pocket of amniotic fluid clear of
all fetal parts
Measure the fluid pocket from
anterior to posterior (at least
1cm)
Document this measurement
for each quadrant of the uterus.
Add the measurements for a
total
Measurement of the largest
single vertical pocket of fluid in
the uterus
Commonly used for twin
pregnancies
Cerebellum
Posterior Fossa
of the Brain
Sagittal
Equal to
gestational age

Move caudal from BPD. Head
must be symmetrical
Nuchal Fold
Skin thickness
on the posterior
head
Coronal
Normal
-less than 6mm
up to 24 weeks
gestation

Same plane as cerebellum
measurement
Cisterna Magna
Anechoic Space
in the Posterior
Fossa
Longest axis of
the kidney
Coronal
Normal

-less than 10 mm
Same plane as cerebellum
measurement
Amount of
cerebrospinal
fluid in ventricle
Coronal
Kidney Length
Lateral Ventricles
Sagittal
Approximately
equal to
gestational age
through 2nd
trimester
Long axis of the kidney measuring
from superior to inferior pole
Less than 10 mm 
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx

Superior to BPD at the level of
the ventricles
Measure at atrium or the
thickest portion of the choroid
plexus (CHP) or glomus
2nd and 3rd Trimester OB Protocol
Color and Spectral Doppler Analysis
Structure
Area of Interest
Plane
Umbilical Artery
Document
umbilical artery
blood flow with
Color Doppler and
Spectral Analysis
in a free loop of
the umbilical cord
Longitudinal
Document
umbilical artery
blood flow with
Color Doppler and
Spectral Analysis
in a free loop of
the umbilical cord
Lateral branches
of the circle of
Willis
Longitudinal
Umbilical Vein
Middle Cerebral
Artery
Normal
Measurement
S/D= less than 3
after 30 week
PI= less than 1.25
after 30 week
Coronal
Comments




RI-less than .7 after
30 weeks

2nd-3rd trimester=
Continuous
forward flow with
increasing mean
velocities until 37
weeks

PI=

Greater than 1.45
before term


Less than 1 by term
(Decreases after 32
weeks)



Ductus Venosus
Shunt between
the umbilical vein
and inferior vena
cava
Transverse
Abdomen
Peak velocity=
50 cm/sec



Angle correct is not needed
Low resistive wave form
High end diastolic flow is
normal
Absence of diastolic flow
indicates fetus is in distress
Reversal of diastolic flow is
severe and seek immediate
help from physician
Pulsations can indicate a
severe condition
Fetal breathing movements
will alter continuous forward
flow pattern
Found slightly caudal to BPD
plane
Same proximal end
Position the head to achieve
a Doppler angle of zero or as
close as possible
High impedance flow with
low diastolic flow
Abnormal flow will display
high diastolic flow
Indicate pre-eclampsia, IUGR
& anemia
High diastolic component
Evaluate the “A” waveabnormal if less than
5cm/sec
Laboratory Values
 Qualitative hCG-urine pregnancy test, results positive or negative
 Quantitative hCG- blood pregnancy test, results indicate possible age of pregnancy
 Alpha Fetoprotein (AFP)-blood test for detection of certain abnormalities at 15-20 weeks
 High indicates open neural tube defect
 Low indicates Down syndrome
 Abnormal in cases of wrong dates, fetal demise or twins
 Triple Screen or Quad Screen-combination of blood test including AFP, unconjugated estriol (uE3), hCG, and
Inhibin A (Quad screen)
 Used to detect chromosome abnormalities
Pathology
 Gray scale sagittal and transverse images including images with 3 measurements (length, width and height)
 Color Doppler image document the presence of blood flow
 Spectral Doppler image document type and velocity of blood flow
HMP:\Protocols\OBGYN Protocols\2nd Trimester Protocol.docx