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