Congenital Anomalies Flashcards
What is CVS?
US directed biopsy of placenta-chorionic villi (chorion fondosum - fetal side of placenta)
tissue removed and cultured for cell growth - evaluated for chromosomal anomalies
What are the different types of genetic testing?
CVS (chorionic villus sampling)
amniocentesis
quadruple screen
What are the advantages to CVS?
performed early in pregnancy
done at 10-14 weeks MA - transcervical
after 10 weeks - transabdominal
Quick results - 1 week
When a CVS is done what is our role?
ultrasound guided - TA or TV
must scan post CVS to confirm fetal viability post procedure
CVS can be done TA or TV, where is the transducer?
TA for both
What are the risks associated with CVS?
Pregnancy loss o.5% to 2%
association with limb reduction defects if done prior to 8 weeks gest.
Rho (D) immune globulin - RhoGAM should be given to Rh-negative unsensitized women
What is an amniocentesis for?
initially used to relieve polyhydramnos
predict Rh isoimmunization
document fetal lung maturity
mid 1960’s used to obtain fetal cells to detect chromosomal abn.
What does amniocentesis evaluate for?
chromosomes 21, 13, 18, x, y
Who gets amniocentesis done the most?
AMA (advanced maternal age)
parent or previous child with chromosomal abn
abn AFP or quad screen
fetus with congenital anom on US
check lung maturity **L/S RATIO FINISH IMPORTANT
What do you document post amnio?
fetal heart rate
look for bleed
What is PUBS?
percutaneous umbilical blood sampling
same as a cordiocentesis
What is a cordiocentesis?
obtain fetal blood from umbilical cord near placental cord insertion
What are the two ways to measure alfa-fetoprotein?
MSAFP - Maternal serum
AFAFP - amniotic fluid alpha-fetoprotein
What are you looking for if there is an elevated AFP?
open neural tube defects (NTD)
What are you looking for if the AFP is decreased?
Chromosomal Abnormalities - trisomy 21, 18, 13
**incorrect dates **
fetal death
hydatidform moles
What does a CVS test detect?
chromosomal abnormalities
biochemical or metabolic disorders
hemoglobinopahies (ie. sickle cell)
If the MSAFP is elevated but has a normal AFAFP what is the baby at risk for?
hydrocephalus
congestive heart disease
88% anencephaly and 79% open spina bifida is detected by what serum?
MSAFP (maternal serum alphafetoprotein)
which blood test is more sensitive for detecting trisomy 21 and 18?
quadruple screen (AFP, hCG, unconjugated estriol, dimeric inhibin A)
If PAPP-A (pregnancy associated plasma protein) is increased in maternal serum throughout pregnancy, what might be wrong if it is decreased?
aneuploidy
what detects Down’s syndrome?
Free Beta Human Chorionic Godadotropin
What is aneuploidy?
abnormality of the number of chromosomes
What is a chromosomal disorder?
too much or too little chromosome material
What is an Autosomal Dominant disorder?
Usually carried by one affected partent
50% chance of occurrence with each pregnancy
What is Autosomal Recessive disorder?
each parent carries defective gene
25% chance of occurrence with each pregnancy
What is a nuchal translucency?
abnormal fluid collection behind fetal neck
What does the nuchal translucency need to measure to be abnormal?
> 3mm
strongly associated with aneuploidy
When is the best time to identify a nuchal translucency?
between 10-14 weeks
What abnormalities are associated with nuchal translucency?
trisomies 13, 18, 21
triploidy
Turner’s
What is trisomy 21?
Down’s Syndrome
extra chromosome number 21
what is the most common chromosomal abnormality?
Trisomy 21 (Down’s Syndrome)
What is trisomy 21 associated with?
advanced maternal age
abn nuchal translucency
abn first trimester screen
abn quad screen
What are some features of a trisomy 21 baby?
flattened nose and face
upward slanting eyes
single palmer crease
short fifth finger that curves inward
widely separated first and second toes and increased skin creases
What is another name for trisomy 18
Edward’s syndrome
2nd most common chromosomal trisomy
extra 18th chromosome
What happens with babies with trisomy 18?
severe mental retardation
often spontaneously abort
90% die in the first year of life
What are some physical features of trisomy 18?
small mouth and jaw
short neck
shield chest (short prominent sternum)
wide set nipples
Clenched hands with overlapping fingers
dysplastic or malformed ears
occiput is prominent
flexed big toe
prominent heels
