Prenatal Diagnosis of Fetal Malformations

combined screening test for chromosomal abnormalities

Down’s, Edwards: US (nuchal translucency), PAPP-A, bHCG @ 11-13+6w

triple screening test for chromosomal abnormalities

Down, trisomy 18, neural tub defects: @15-16w, estriol, hCH, AFP

quadruple screening test for chromosomal abnormalities

triple test + inhibin A, @15-16w

integrated screening test for chromosomal abnormalities

PAPP-A @10w, nuchal translucency @ 11-13+6w → test again at 15w

integrated serum screening test for chromosomal abnormalities

US for dating

PAPP-A @10w + quadruple test @15w

results of relative risk (RR) of Down’s sd after combined screening test

intermediate 1/300 and 1/100

increased >1/100

what to do if RR of Down’s sd after combined screening test is increased (>1/100)

dg thru chorionic villus sampling/amnio

non-invasive screning test (NIPT) for chromosomal abnormalities

test for trisomies 13,18,21, triploidy and determining sex chromosomes

invasive fetal dg of genetic disorders

chorionic villus sampling, amniocentesis

when can you do chorionic villus sampling

10-13w

risks chorionic villus sampling

spontaneous abortion

false -

vertical transmission hiv or hep

when can you do amniocentesis

after 15w

risks amniocentesis

spontaneous abortion (risk lower than is CVS)

most common indication fetal blood sampling

analyzing fetal anemia

_____: This is performed for DIAGNOSING CHROMOSOMAL DISORDERS. IT IS RECOMMENDED WHEN THE ULTRASOUND APPEARANCE IS HIGHLY SUGGESTIVE OF A TRISOMY, MONOSOM

karotype analysis

_________TARGETS SPECIFIC SYNDROMES (E.G., WILLIAMS SYNDROME OR DIGEORGE SYNDROME), but has the disadvantage of limited detection capabilities for known genetic loci

FISH

indications for molecular genetic testing

• detection aneuploidy in prenatal dg

• family member or parent carrier or affected by single-gene disorder

• phenotype of genetic sd

preimplantation genetic testing is for which couples

for IVF

In the first trimester, the ultrasound markers for chromosomal abnormalities include:

• nuchal translucency >3mm

• nasal bone absent

• ductus venosos (reverse flow0

• tricuspid regurg

US markers of chromosomal abnormalities in second trimester

• increased nuchal fold thickness >6mm

• short femur + humerus

• cardiac anomalies

the 2 important morpho US for evaluation of fetal structure - timing

first trimester - 11w - 13+6d

second - 18-22w

indications fetal therapy

• fetal anemia

• pleural effusion

• aortic/pul valve stenosis

• arrhythmias

• diaphragmatic hernia

• twin-twin transfusion sd