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
US Markers with reassuring cfDNA testing, some will still demaAnd f/u:
What can we offer for short long bones?
- 3rd trimester US to assess growth
- very short long bones -> consider single gene testing b/c assocaited with skeletal dysplasias
some skeletal dysplasias are not obvious on US until 3rd trimester
these are typically non-lethal by chest cicumference
What is another group of monogenic conditions that are associated with short long bones other than skeletal dysplasias?
relatively short long bones
RASopathies (Noonan)
- Cardio-facio-cutaneous syndrome US findings: 10% in 1st tri, 61% in 2nd tri, 79% in 3rd tr
- polyhydramnios is very common
these fetuses usually are macrosomic (large)
What is rocker bottom feet assocaited with?
trisomy 18
What are clenched hands associated with?
trisomy 18 and neurological damage
What is ventriculomegaly?
- the brain ventricles are enlarged due to a buildup of Cerebrospinal fluid
- has its own risks even in the absence of aneuploidy: intellectual disability (but >90% have normal intellect)
What are the potential outcomes for the US finding of mild ventriculomegaly?
- isolated: >90% favorable outcome
- 7-10% have anomaly (incrased fluid = increased risk for ID)
- fetal MRI available
mild ventriculomegaly in Tri 18
What are some potential etiologies outside of aneuploidy that could lead to milld ventriculomegaly?
- chromosomal
- infectious
- teratogenic
- molecular
What major anomalies are associated with aneuploidies?
- congenital heart disease
- clubfoot
- facial clefting
- omphalocele (organs sick out through belly button)
- congenital diaphragmatic hernia (hole in the diaphragm)
- differences of sexual development
What is the incidence of congenital heart disease?
1 in 100 live births
What is the critical period for fetal heart development?
5-8 weeks gestation
What percentage of CHD is found with another anomaly?
25%
How often is CHD associated with a syndrome?
10%
What percentage of CHD cases have aneuploidy?
5%
What percentage of CHDs have DiGeorge Syndrome?
22q11.2 deletion syndrome
7%
- Common findings include conotruncal defects (congenital malformation of the outflow tract of the heart: like ToF, interrupted aortic arch, and pulmonary atresia)
What percentage of CHDs have a single-gene disorder?
3-5%
ex: Noonan syndrome
Environmental causes are responsible for 2% of all CHDs. What are these?
- teratogens: rubella, lithium, alcohol, trimethadione
- matenral conditions: poorly controlled diabetes, SLE (Lupus), PKu (25% risk for CHD), maternal CHD or 1st degree relative
Which syndrome is the CHD conotruncal defect associated with?
(congenital malformation of the outflow tract of the heart: like ToF, interrupted aortic arch, and pulmonary atresia)
22q11.2 deletion syndrome
DiGeorge Syndrome
- almost 3/4 of patients with DiGeorge have CHD
Which syndrome is the CHD supravalvular aortic stenosis associated with?
section of the aorta narrowed
Williams syndrome (7q11.23 deletion)
- over 3/4 of Williams have CHD
What syndrome is CHD coarctation of the aorta associated with?
narrowing of the aorta
45X / Monosomy X / Turner Syndrome
- up to half of pts have CHD
What syndrome is CHD AV (atrioventricular) Canal defect associated with?
hole in wall separating heart’s chambers & problems w/ the heart valves
trisomy 21
- about half of these patients have CHD
What syndrome is CHD pulmonic stenosis associated with?
Noonan Syndrome
- and RASopathies in general
- about 3/4 have CHD
Incidence of clubfoot
1 in 1,000
but this goes up if cases of less severe clubbing are included
What percentage of clubfoot cases are assoacited with an identifiable cause and what are these?
30-40%
- ONTD
- intrauterine constraint (w/out much amniotic fluid there is cramming)
- neuromuscular disease (feet turned in if not moving as much)
Waht is the overall incidence of cleft lip and palate and which populations is the incidence higher?
1 in 700
Asians and Native Americans = 1 in 500
When during pregnancy are the lips and palate formed?
lips: by 4-7 week gestation
palate: by 6-9 weeks gestation
What percentage of cleft lip and palata and celft palate are associated with syndromes? And what is the most common?
CL(P) = 5%
CP = 8%
aneupolidy is most common
Conditions that are assocaited with facial clefting
- aneuploidy ( most common)
- Van der Woode: AR, 1% of CL(P), lip pits
- ectrodactyly ectodermal dysplasia: affects formation of hands, lobster claw, CL(P) or CP
- Treacher Collins: AD, CP 28-35% of the time
- Stickler syndrome: AD, CP 25% of the time
Are facial clefts reapired immediately after delivery?
No, babies go home with clefts
What are enviornmental caues of facial clefting?
- teratogens: alcohol, hydotoin, trimethadione, aminopterin
- maternal conditions: uncontrolled diabetes
Omphalocele is often associated with other anomalies. What is the risk for associated CHD?
10%
If there are midline defects, what condition should we consider?
trisomy 13
What syndromes are associated with omphalocele?
- aneuploidy (30% risk) (midline defect so think trisomy 13)
- Beckwith Wiedemann (this may be their only US finding)
What is the incidence of congenital diaphragmatic hernia?
less common
3 in 10,000
associated malformations are present in about 50% of patients
How does having syndromic CDH (vs isolated) affect outcomes?
It is worse!
Individuals with syndromic CDH are more likely to be diagnosed prenatally, have
an affected first-degree relative (10%), and have a worse prognosis. More than
50% of individuals with syndromic CDH are born preterm and have low birth
weight. Which makes repair challenging.
What is the most common chromosomal cause of ambiguous genitalia?
X/XY mosaicim
I think this is the same thing as mosaic Turners (XO/XY)
Incidence of ambiguous genitalia?
1 in 1,000 - 4,500
2/3 will also have non-genital anomalies
What percentage of ambiguous genitalia identifed on US will end up having a difference of sexual development postnatally?
80%
What percentage of ambiguous genitaia cases have a genetic etiology?
25%
X/XY mosaicim is the most common chromosomal cause
Are ONTDs often assocaited with aneuploidy?
No
What is requried for fetal surgery for ONTD ‘repair’?
- karyotype
- CMA
Which is more concerning: echogenic bowel or echogenic heart?
echogenic bowel
