Ultrasound screening; soft markers and anomalies Part 2 Flashcards
Which trisomies is ultrasound in the 2nd trimester most effective at detecting?
trisomies 13 and 18 because thse fetuses are more severly affected in general so there is more to find. detection rate of about 90%
detection rate is only about 50% for trisomy 21
What is the measurement of an increased nuchal fold in the 2nd trimester?
> 6mm
Will an increased nuchal fold be obvious once the baby is born?
there may be extra skin but it is not a very obvious finding postnatally
What did urinary tract dilation used to be called?
pyelectasis
What measurement is considered urinary tract dilation?
> 4mm at less than 28 weeks
after 28 weeks expect more fluid
Short femurs and or humeri are assocaited with…
<5th percentile for gestational age
trisomy 21
or… just consitutional short stature (short like parents)
<0.9 MOM for bi-parietal diameter (compared to baby’s head)
Hypoplastic nasal bone is easier to see….
in the 2nd trimester
Absent nasal bone is a good marker for ________ in which population?
trisomy 21
white people
lesser assocaition for Asians and black people b/c of normal variation
What risks are assocaited with single umbilical artery?
None
used to think associated with trisomy 18 and caridac defect, but now we do not think there is a reason to worry about it
Ithink trisomy 21 (check required)
What are choroid plexus cysts(CPC)?
- A choroid plexus cyst happens when a small amount of the cerebrospinal fluid gets trapped in the layer of cells as your baby’s brain grows and develops. The cysts may go away on their own during pregnancy. Choroid plexus cysts can happen in any pregnancy.
- have been found incidentally in healthy adults
- not brain malformations and do not affect brain development
What is the choroid plexus?
the part of the brain that makes the fluid that surrounds the brain and spinal cord
Are choroid plexus cysts followed by ultrasound?
No, and there is no greater assumption of risk whether they dissappear or not.
Are there risks associated with choroid plexus cysts?
- If an isolated finding - no.
- CPC + cardiac defect = increase risk of trisomy 18 .
- We offer screening for trisomy 18 even if isolated just because
In general, any ultrasound anomaly will qualify a patient for ____ at least.
NIPT
What does an echogenic intracardiac focus look like and what is it assocaited with?
- looks like a bright white spot where we would expect grey
- could be just a calcium deposit
- does not affect the development of the heart
- weak association with trisomy 21
What are the colors of an ultrasound and what do they represent?
- bright white = bone
- fluid = black
- tissue (organs) = gray
How to describe echogenic intracardiac focus to a patient.
- bright white where we expect gray
- most likely harmless calcium deposits
- commonly seen, do not affect development of the heart
- when seen alone, negligbile risk for Downs
What risks are associated with echogenic bowel?
- 1-3% fetal cystic fibrosis
- 1-3% congenital infection (25% CMV)
- 1-2% GI obstruction (bright white is the obstruction)
Trisomy21 = can see in 2nd Trimester
Perinatology.com is a resource for what?
- to estimate the risk for Down syndrome
- considers age along with ultrasound anomalies
Likelihood atios are numbers that we multiply the a priori risk by based on certain fidnings to determine the new risk. Which likelihood ratios are the highest? Meaning, which ultrasound findings have the largest impact on increasing risk?
LR X Age Risk/masternal serum/NIPT = New Risk
nuchal fold: 15-20 x risk (Downs)
hypoplastic or absent nasal bone: 14-23 x (Downs)
Which 3 ultrasound findings have very low liklihood ratios?
- single umbilical artery = ?? (aneuploidy)
- choroid plexus cyst = negligible if isolated (with cardiac defect = trisomy 18)
- urinary tract dilation <2% (Downs)
Which ultrasound findings have more moderate likelihood ratios?
- echogenic intracardiac focus = 1.5-5% (Downs)
- echogenic bowel = 5-10% (Downs)
- short femur = <5% (Downs)
- short humerus = 5-10% (Downs)d
Which ultrasound findings are not strongly associated with Downs?
- single umbilical artery
- urinary tract dilation
- choroid plexus cyst
- echogenic intracardiac focus
- short femur
How do we calculate risk utilizing the likelihood ratios?
- multiply the most accurate screening test result available (a priori risk) by the corresponding likelihood rato
- screening test accuracy from least to most: age -> matenral serum screening -> NIPT
- usually defaults to 1 in 10,000 residual risk after NIPT (I’m not sure what this means)
LR X a priori Risk = New Risk
US Markers with reassuring cfDNA testing, some will still demand f/u:
What can we offer for urinary tract dilation?
3rd trimester ultrasound to assess for obstruction, if still dialated may want to give birth at tertiary care hospital
US Markers with reassuring cfDNA testing, some will still demaAnd f/u:
What can we offer for echogenic bowel?
- testing for cystic fibrosis (carrier testing) and infectious etiologies
- reassess US in 3rd trimester
NIPT,Amnio (active infections can be checked)
US Markers with reassuring cfDNA testing, some will still demaAnd f/u:
What can we offer for single umbilical artery?
- check fundal height to see if what is expected
- 3rd trimester US to assess growth if not in line