Prenatal diseases Flashcards
Embrogenesis: WHat is happening at each week: Week 0 Week 1 Week 2 Week 3 Weeks 3-8 Week 4 Week 8
Week 0 : fertilization, cell division (blastula → morula → blastocyst)
Week 1: implantation + β-HCG secretion
Week 2: bilaminar disc (epiblast + hypoblast)
Week 3: gastrulation (3 tissues), neurulation
Week 3-8: organogenesis (most susceptible to teratogens)
Week 4: heart (4 chambers), limbs (4 limbs)
Week 8: fetus
What does each layer become:
endoderm
mesoderm
ectoerm
endoderm = GI and respiratory systems
mesoderm: CV, MSK, GU
ectoderm: CNS, skin
when does neural tube close
4 wks
what can cause the defective neural tube closure?
folate def
mutation methyl-THF-reductase
↑αFP, confirm U/S shows lemon sign (concave frontal bones) and banana sign (flat caudal cerebellum)
myeloneningocele
asx lumbar tuft of hair
spina bifida occulta
calcification of papillary muscle on U/S
echogenic intracardiac focus (EIF), usually insignificant
presentation of R to L shunts vs L to R shunts
R to L have early cyanosis
L to R have late cyanosis (dev PAH = eisenmerger syndrme)
What are the R to L shunts? L to R?
R to L = TOF, transposition great vessels
L to R = ASD, VSD, PDA
cardiac defect often seen with Congenital Rubella Syndrome
PDA
presents as low-grade systolic murmur, fixed S2, and frequent colds
ASD
presents as pansystolic harsh-sounding murmur with failure to thrive
VSD
presents as cyanosis and clubbing in a 5 y/o child who squats for relief;
TOF
prognosis of TOF determined by
degress of pulmonic stenosis
What is pathophys of Potter’s sequence
failure of mesonephros and metanephros to meet at ureteropelvic junction → bilateral renal agenesis → anhydramnios (no amniotic fluid) → pulmonary hypoplasia + limb contractures
How is potters seq diagnosed?
U/S shows anhydramnios or oligohydramnios (AFI <5)
treatment for potters seq?
none
insert needle transabdominally into uterus
and withdraw amniotic fluid
amniocentesis
insert catheter into intrauterine cavity and
aspirate chorionic villi from placenta
chorionic blood sampling (CVS)
insert needle transabdominally into uterus
and withdraw umbilical cord blood
percutaneous umbilical blood sampling
what prenatal sampling metho is best for rapid karyotype analysis of fetus
percutaneous umbilical blood sampling (PUBS)
amniocentesis or chorionic blood sampling assc with greater risk of PROM, PTL, and injury
chorionic blood sampling (CVS)
what prenatal sampling technique is best in 1st trimester
chorionic blood sampling (CVS)
how is CF diagnosed prenatally?
screen mom and dad for ΔF508/G542X, and confirm with fetal dx
How is sickle cell dz diagnosed prenatal?
screen mom w/ Hb electrophoresis, then dad if positive, then confirm w/ fetal dx
mutation assc with tay sachs
AR ΔHexA → ganglioside accumulation →progressive neurodegeneration, developmental delay, “cherry red spot” on macula, onion-skin lysosomes
Beta thal vs alpha thal mutations
beta = AR deletion in Beta chain = inc alpha:beta hgb ratio
alpha: cummulative deletions in alpha chain = dec alpha:beta ratio!
Silent carrier: 1-2 gene deletion; asx
HbH disease: 3 gene deletion → ↑HbH (β4) → severe microcytic anemia
Barts disease: 4 gene deletion → ↑HbBarts (γ4) → hydrops fetalis (IUFD)
how are thalasemmias diagnosed?
screen w/ CBC, if microcytic anemia then confirm w/ Hb electrophoresis
trisomy 21
down
trisomy 13
patau
trisomy 18
edwards
45, Xo
turners
Coarctation of aorta Lymphedema Ovarian dysgenesis Webbed neck (cystic hygroma) Nipples spread (shield chest) Short stature
47, XXY
klienfleters
female traits on a man (long legs, gyno, highpitched
voice, female habitus, etc.)
5p-
cri-du-chat syndrome
microcephaly, cardiac problems, high-pitched
meowing, epicanthal folds, MR
7q-
williams
Elfin facies, Extreme friendliness w/ strangers,
well-developed English, MR
22q11
Digeorge
Cleft palate Abnormal facies Thymic aplasia Cardiac defects Hypocalcemia
diagnosed with quad screen at 15-20 wk (↑β-HCG, ↑inhibin,
↓αFP, ↓estriol) + nuchal translucency on
U/S ;
downs
diagnosed with triple screen (↓β-HCG, ↓αFP, ↓estriol)
edwards
trisomy found on routine US
patau
cleft lip/Palate, holoProsencephaly, Polydactyly,
rocker-bottom feet, MR; death by 1 y/o
patau
micrognathia, clenched hands, rocker-bottom
feet, MR; death by 1 y/o
edwards
