Mod 7 2nd Trimester Detailed Anatomy Ultrasound Flashcards
When would a detailed anatomy scan be performed?
18-20 weeks gestation.
What is assessed on a detailed anatomy scan at 18-20 weeks? What is also done?
- All organs are demonstrated to assess for anatomic defects.
- Biometry is also performed
The detailed 2nd trimester exam is how long?
45-60 minutes let your patient know at the beginning of the exam
When doing the detailed Anatomy example we should always be aware of the patients what? 3
Possible discomfort of things like
1. Full bladder
2. Backache
3. Supine hypotension
What should we do to make the patient more comfortable? 3
- Reassure patient if bladder is uncomfortably full that you will take a few images and then have a pee break
- Offer a extra pillow or raise the head of the bed slightly
- Cushions can be placed under the knees or have your patient bend their left knee
What is supine hypotension?
Caused by pregnancy putting pressure on the IVC and lower aorta, reducing venous return.
What are signs and symptoms of supine hypotension? 5
- Fidgeting patient
- feeling hot
- Light headed
- Nauseous
- Faint
If the patient starts to exhibit signs of supine hypotension what should we do? 4
- Immediately roll her on her side (left side is best)
- Patient may need to sit up for a brief time
- Can turn on a fan or offer a glass of water
- Can scan with patient tilted to the left
What do we look for in a sagittal sweep in the detailed anatomy scan? 4
- The position of the fetus
- Check for fetal heart motion
- Check for the number of fetuses
- Assess for the presence of amniotic fluid
What is the Sagittal sweep process for the detailed anatomy scan?
Sweep in sagittal from midline through uterus laterally to each adnexa and back
What do we look for on a transverse sweep of the detailed anatomy scan? 2
- Assess for fibroids on the uterus
- Assess for adnexal masses usually arising from the ovary
What is the process for the transverse sweep of the detailed anatomy scan?
Sweep through midline uterus and along the lateral aspect of the uterus to include adnexa, all the way up to umbilicus
If we find fibroids on the uterus during the detailed anatomy scan what should we do?
Document these findings in two planes and measure in three
What are some adnexal masses we might see in a transverse detailed anatomy scan? and what should we do? 2
- Corpus luteal cysts
- Dermoid cysts
document these findings in two planes and measure in three dimensions
When documenting the cervix during second trimester what should we do?
- Document the length of the cervix
- Normal is >3cm
- Measure from Inner OS to External OS
What are these images representing?
A contraction happening during the ultrasound. This is called the 9 cm cervix
What is the pitfall here for the scan? And what are the negatives
Overall distended bladder can also cause the bladder measure to be overestimated. Can also falsely make a shortened cervix look long. Come back to it later after voiding. This kind of full bladder can potentially hide pathology
What is the red arrow pointing to?
Anterior placenta
What is the red arrow pointing towards?
Posterior fundal placenta
How do we document the placenta? and what do we assess?
- Document the placental position in transverse and sagittal
- Assess the placental texture and thickness
The placenta grows how much per week?
1mm/wk
What is this a picture of?
SAG placenta
What is this a image of?
TRX placenta
When measuring the placenta how should it be done? Placenta should be how far from the cervix?
- Measure from the placental edge to the Internal OS of the cervix
- Placenta should be a minimum of 2 cm away from the internal OS of the cervix
What planes should we document the placenta in?
SAG and TRX
The placenta cord insertion should be how far form the placental edge?
> 2cm in both planes
After a brief survey of the uterus you should have established what? 5
- Viable fetus
- Fetal lie
- Fetal number
- Placental localization
- Uterine or adnexal pathology
After sweeps and documental of maternal structures what do we do next?
Image fetal anatomy in groupings based on fetal position
What is opportunistic scanning?
Take what the fetus is showing you, we do this because sometimes it can be difficult or sometimes impossible to image some fetal anatomy if the fetus is not in an optimal position.
Where do we start with the fetal anatomy scans? 2
- After your sweep, decide which fetal anatomy is in the best position to image or document
- Start with whatever is “up”
If the heart is visible, do that first because it is harder to get
What are the fetal anatomy groupings? 6
- Head
- Spine
- Abdomen
- Heart
- Limbs (upper and lower)
- Gender
What are some fetal head images? 8
- BPD, HC
- Ventricles
- Bilateral choroid image
- Cerebellar image/ posterior fossa
- Orbital image
- Nose lip image
- Face image
- Profile
When imaging the fetal head what should we look for? 5
- Asses the head shape
- High on the fetal head or cephalic on the fetus is the head shape is round?
- At the BPD level is the fetal head is more oval
- Does the Calvarium have a smooth appearance?
- Is the head Dolichocephalic (narrow), Normal, Brachycephalic (wide)
Label the fetal head
- Transventricular plane
- BPD
- Transcerebelar
What is the BPD measurement criteria? 4
- Perpendicular to the Falx
- Symmetric hemispheres
- Measure the widest point across the skull
- Calipers placed from leading edge to leading edge
During the BPD image what do we assess? 5
- Cavum septi pellucidi
- The third ventricle
- Ambient cisterna
- The falx cerbri
- Shape of the cranium
What does the ventricular image assess? 3
- The dependent ventricle (the ventricle farthest from the transducer)
- Echotexture of depended choroid
- Measurement of atrium size
What does the bilateral choroid image do?
Assess the echotexture of both choroid together
What is the Cerebellar image/ posterior fossa window used for? 3
- Used to assess the cerebellar shape and size
- Presence and size of the cisterna magna
- Nuchal fold thickness
A large cisterna is a marker for what?
Aneuploidy
What is this an image of?
Dandy walker malformation. Cerebellar vermis is absent, cyst in cisterna magna
What is the orbital image used to assess? 4
- Hypertelorism (eyes too far apart)
- Hypotelorism (eyes too close together)
- Size of the orbits (micropthalmia = small eyes)
- Anopthalima (no eyes)
If we see lens during the orbital image what does this mean?
anopthalima
What is this an image of?
Orbital image
What is this an image of?
Fetal face image
What is this an image of?
Fetal face image
What is the nose lip image? and what is it used for? 3
- This image skims the nose and lip
- Tangential plane
- Taken to rule out Cleft lip and abnormal nostrils
What are these images of?
Nose lip image
How do we get a profile image?
Line up the forehead, nose and chin on this image
What is this an image of?
Profile shot
What do we assess in a profile image? 2
- Chin
- Nasal bone
What do we assess in the chin for the profile shot? 2
- Micrognathia: Small mandible
- Retrognathia: Receding Chin
What do we assess in the nasal bone for the profile image? 2
- If it presents >2.5mm
- Absent or hypoplastic
What is this an image of?
BPD (transthalamic view)
What is this an image of?
Posterior Fossa
What is this an image of?
Choroid
What are the fetal spine images taken in the 2nd trimester? 4
- Sagittal upper, mid, and lower spine
- TRX at the level of sacrum
- TRX kidneys with renal pelvisies
- Sagittal kidneys if possible
What area already assessed will help validate a normal spine?
Posterior fossa images for banana sign
How many ossification centers are there?
three
What are the only things visible on the fetal spine ultrasound?
Ossification centers
The anterior ossification center is what?
The vertebral body
The posterior ossifications are what?
Pedicle laminar junction
As the gestational age increases, the lamina does what?
Ossifies into a linear structure rather than circular
Ossification is not complete until which week?
18 weeks gestation
We must view the spine on how many planes?
- TRX
- SAG
*if you can not view in a sagittal plane, then a coronal view is acceptable)
What images should we have for the fetal spine in sagittal? 2
- One image at distal end to include the sacrum
- One image at the cephalic end to include cervical spine into cranium
What images should we have for the fetal spine in sagittal? 2
- One image at distal end to include the sacrum
- One image at the cephalic end to include cervical spine into cranium
When imaging the spine we should include as many what as possible?
Vertebral ossifications in image as possible
Most important thing to do for a spine image is to do what?
Sweep through spine in transverse
How many images are taken for a TRX spine?
- One image taken at the lumbosacral junction
What is this an image of?
SAG Cervical Spine
What is this an image of?
SAG Lumbar and sacral spine
When imaging the TRX spine at sacrum it is ideal to image what? and how?
Both iliac crests and all three ossification centers in transverse, with the transducer directly over spine “spine up”.
When getting a TRX spine image at sacrum we should try to image away from where? what else is seen here? 2
- try to image spine away from uterine wall
- Fetal bladder is seen as well
Where are the kidneys located on 2nd trimester scan? What do they lack at this stage?
- Either side of the spine
- Lack distinction during this trimester
What is the dimensions of the kidneys during this trimesters? (In terms of renal dilation)
Over 5mm is the upper limit
What is the sonographic appearance of the renal pelvises around this trimester?
hypoechoic and minimally dilated up to 3mm
What should we assess from the images of the kidneys?
Compare the size of them to see if they are normal or abnormal
Where should the kidneys present in this trimester? ( In relation to the spine)
With the Spine in middle
Longitudinal images of the kidneys are done when what happens? 2
If any abnormality is detected in the kidney such as
1. Hydronephrosis
2. Renal cysts
What is this an image of?
TRX kidneys
What is this an image of?
Coronal kidneys
Where are the adrenals located on the fetus during this trimester?
Superior and medial to kidneys
What is the sonographic appearance of the adrenals during this trimester?
Hypoechoic with echogenic centers
What is this an image of?
Neonatal adrenal
What are the fetal abdomen images we need to take? 6
- Abdominal circumference
- Stomach
- Cord insertion into abdomen
- Bladder
- Two umbilical arteries
- Three vessel cords
+/- SAG diaphragm with stomach and heart (can be imaged with abdomen or with heart)
What does Abdominal circumference (AC) assess? 2
- Presence of stomach and position of organs
- Is the stomach on the left side?
What might/might not be seen during the abdominal circumference image? 2
- The GB may be seen.
- Do not confuse it for the stomach
- IT is ovoid looking and is on the right side - Should only see one stomach bubble
What are some landmarks of the AC image? 6
- Stomach
- Umbilical vein draining into portal sinus
- Round shape
- Rib symmetry (unbroken ribs)
- Adrenal glands
- Spine
What does the fetal bladder look like during this trimester? How often should it fill and empty?
- Anechoic structure between iliac crests
- Should fill and empty every 20 minutes
What does the presence of the bladder indicate?
At least one functioning kidney
What is this an image of?
Fetal bladder
When we get an image of the cord insertion into fetal abdomen what do we need to do?
Ensure clear, unobstructed visualization of cord insertion with no fetal parts in the way
What is this an image of?
Cord insertion into fetal abdomen
What does the umbilical cord look like in TRX during this trimester? What should we see? 2
- Looks like micky mouse ears.
- Two arteries and one vein
Where and why should we image the umbilical cords
Image the cord insertion into fetal abdomen to check for abdominal wall defects
Where is the insertion into the placenta?
The cord should insert into the placenta more than 2 cm away from the edge of the placenta
When we image the Umbilical cord what can be associated with congenital abnormalities?
2 VC and 1 UA. Fetal echo is indicated when identified
When imaging the 2 umbilical arteries at bladder what should we identify? What do we need to do with this view? How do we confirm this image?
- Right and left umbilical arteries around bladder
- Document this view
- Add colour doppler or power doppler
If we want to image the two umbilical arteries at bladder how should we proceed? What must we see from the CI? What does this prove? What does the two UA become?
- Angle obliquely inferior from CI to include bladder
- Must see colour fill continuously from CI forking around bladder w/o interruption
- If done correctly, this proves 3VC
- two UA become hypogastric/ internal iliac arteries
Where does the placental cord insert into? 2 (think both sides)
- Fetal abdomen
- Placenta
>2cm from placental edge
What can be imaged with the longitudinal image of abdomen and chest?
Abdomen with or without heart
Why do we take a longitudinal image of abdomen and chest? 2
- Assess location of stomach in relation to diaphragm
- Assess echotexture of lungs compared to liver
For the longitudinal image of abdomen and chest, how should the echotexture of lungs compare to the liver? (During the 2nd and 3rd trimester)
- Should be isoechoic to lungs in the 2nd trimester
- Slightly increased echogenicity to liver in the 3rd trimester
What structures should be included in the longitudinal abdomen and chest image? 3
- Heart
- Diaphragm
- Stomach
these images are relative to position of the baby/ fetal lie
How does the bowel appear during the 2nd trimester?
Appears as a cluster of rings bordered by large bowel
How does the colon (large bowel) appear in the 3rd trimester?
May contain meconium particles and appear hypoechoic and prominent
How big is the large bowel at term?
17mm at term
What images do we take of the heart during the 2nd trimester? 7
- 4 chamber
- IVS (Horizontal 4CH)
- M-mode heart tracing
- Left outflow tract
- Right outflow tract
- Three vessel view
- Heart axis/ situs
How do we locate the 4CH in this trimester?
From on- axis fetal abdomen AC view, slide cephalic on baby to find or angle up from stomach
How do we find LVOT, RVOT, three vessel view during this trimester?
RVOT:From 4CH keep tilting/slide superior to locate (toward the head)
LVOT: slowly rotate the head of the probe until the LVOT appears (try both directions)
Why do we take a 4 chamber view of the fetal heart?
To assess the size of all chambers and valve placement
Why do we take an M-mode image of the fetal heart?
To measure fetal heart rate
What is the significance of this image?
This is the level you would do a chest circumference if needed. Not routinely done
What do we look for on a 4CH view for this trimester? 3
- Heart position: located left of midline
- Heart axis: apex points about 45 degrees to the left
- Heart size: occupies about 1/3 of the chest
How do we optimize our fetal heart image? 4
- Use fetal echo preset
- Decrease sector width
- Zoom
- Increase contrast
What is the situs of the organs?
Stomach and heart are both on the fetal left
Why do we need to know the situs of the organs? 3
- Need to know fetal position
- Where is the spine
- Which side of baby is down/up
What is this a image of?
Intraventricular septum view of the fetal heart
What is this an image of from left to right
LVOT and RVOT
What are outflow images done for?
To rule out vessel abnormalities
What is this an image of?
Left outflow of the heart
What is this an image of?
Right outflow
What is this an image of ?
Three vessel view
What structures are primarily focused on for a three vessel view?
- MPA
- AO
- SVC
What is the size of the structures of the three vessel view from largest to smallest?
- MPA
- AO
- SVC
What are the steps to getting a cine clip demonstrating the fetal heart for the 2nd trimester? 2
- Beginning at the fetal stomach in transverse plane
- Slowly sweep cephalic on the fetus
What should be demonstrated on the fetal heart cine clip? 5
- Stomach
- 4CH
- LVOT
- RVOT
- Three chamber view
The fetal heart is in which plane in the fetal chest?
Horizontal
While performing the cine clip from the four chamber view, the LVOT should appear how? The RVOT?
Without any change in the transducer plane just tilting. The RVOT should follow
While performing the clip when and where should the three vessel view appear?
Left and just superior to the RVOT
What are some images we take for the fetal limbs? 7
- Femur length
- Humerus length
- Lower limbs (tib/tib)
- Upper limbs (rad/ulna)
- Foot/ ankle angles
- Feet - palmer view
- Hands
Can all bones be assessed on ultrasound?
Yes
Routinely the femur is measured at each visit starting when?
> 14 weeks
The humerus is measured when?
During the 2nd trimester detailed exam
What do we assess for during bone scans?3
Assess for
1. Size
2. Presence
3. Shape
To assess for skeletal dysplasia or aneuploidy
What are the criteria for measuring Femur length? 5
- Must be perpendicular to sound beam and straight
- Measure femur closest to transducer (image both left and right)
- Both Ends of bone clearly visible
- Calipers placed at each end of the bone, bisecting the shaft
- Only measure diaphysis
When is the epiphysis seen?
> 32 weeks
How do we make the femur perpendicular?
Heal/toe
What are some lower limbs bones we scan? 3
- Femur
- Tibia
- Fibula
What do we need to remember about the lower limb bones? 2
- Tibia is thicker than fibula
- Tibia is medial
What is this an image of?
Rt and Lt ankle
What are the upper limb bones we image? 2
- Humerus
- Forearm (radius and ulna)
What is something we need to remember about the radius and the ulna? 2
- The ulna is medial and forms elbow joint
- The radius is lateral and forms wrist joint
In what instances would you be required to measure all long bones?
Syndromes and chromosomal abnormalities
What are the long bones that we would image? 6
Right and Left
1. Tibia and fibula
2. Femur
3. Radius and Ulna
4. Humerus
5. Clavicles
6. Chest circumference
What is this an image of?
Clavicles
Is the genitalia routinely documented?
- Yes (site dependent)
- Important to document with twins and suspected sex linked syndromes
What are the pitfalls of imaging genitalia in the 2nd trimester? 5
- The labia can be swollen and be mistaken for a scrotum
- Testicles do not descend until 28 weeks gestation
- Scrotum can be tucked up between legs
- Position dependent - legs need to be open
- Breech babies are difficult to see
What is the sign we kind use to find out the gender here?
This is a female FYI
1. Hamburger sign
2. Female: 3 parallel lines signifying interfaces of the labia
What gender is this child? and how do we know?
This is a male
1. We use the turtle sign to figure out the gender
2. Turtle = visible penis and scrotum
When is amniotic fluid measured?
2nd trimester detailed assessment
A subjective assessment of amniotic fluid is observed when?
When the fluid is
1. Subjectively decreased
2. Subjectively increased
What is the DVP?
Deepest vertical pocket of fluid and what is measured
When is AFI (amniotic fluid index) measured?
26-28 weeks
Amniotic fluid increase until when?
34 weeks then slowly diminishes
Amniotic fluid is mostly produced by what?
Fetal urinary system.
to lesser extents by the umbilical cord, lungs, and skin in early pregnancy
What is the vernix?
Skin cells floating in the fluid