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Ob/Gyne > Module 10 : Fetal Chromosomal Abnormalities > Flashcards

Module 10 : Fetal Chromosomal Abnormalities Flashcards

1
Q

aneuploidy - définition

A
  • state of having an abnormal number of chromosomes (1 extra or 1 less)
    + means bad set
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2
Q

euploidy

A
  • means good set
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3
Q

trisomy

A
  • one extra complete or partial chromosome (47XY)

- 21, 18, 13

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4
Q

triploidy

A
  • a complete extra set of chromosomes (69 XXY)

- form of polyploidy

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5
Q

monosomy turners syndrome

A
  • 45Xo
  • missing an X or Y from paternal (fathers) side
  • always female
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6
Q

aneuploidy

A
  • meiotic error that causes aneuploidy is call non disjunction
  • chromosome pair fails to separate during meiosis
    + the sperm of oocyte has 2 copies of particular chromosome or no copies instead of one copy in haploid state
  • once fertilization occurs in zygote wither has 45 or 47 chromosomes rather than 46
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7
Q

chromosome abnormalities

A
  • 1/160 live born infants has a chromosome abnormalities
  • most common LIVE born chromosome abnormality is trisomy 21
  • most common chromosome abnormality among spontaneously aborted fetus is turners
  • trisomy 18 and 13 more severe than trisomy 21
  • other trisomies rarely seen with lethal result
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8
Q

trisomy 21

A
  • cardiac abnormalities are the major cause of increased mortality in infancy
  • decreased intelligence
    + severity varies
  • increased risk of down syndrome with late maternal age
  • not considered lethal
  • maternal serum prenatal screen second trimester or quad screen 60% detection rate
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9
Q

quad screen elements

A
  • AFP
  • EU
  • hCG
  • Inhibin A
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10
Q

AFP

A
  • alpha-fetoprotein

- produced by fetal liver

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11
Q

EU

A
  • unconjugated estriol

- produced by fetal liver and placenta

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12
Q

hCG

A
  • human chorionic gonadotropin

- produced by the placenta

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13
Q

Inhibin A

A
  • hormone produced by the placenta
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14
Q

triple screen - trisomy 21

A
  • MSAFP decreases
  • B hCG increases
  • UE3 decreases
  • inhibit A increases
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15
Q

triple screen - trisomy 18

A
  • MSAFP decreases
  • B hCG decreases
  • UE3 decreases
  • inhibin A doesnt change
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16
Q

triple screen - trisomy 13

A
  • not predicted with quad screen
17
Q

trisomy 21 sonographic appearance

A
  • thick nuchal fold > 6mm
  • heart defects
    + AVSD
    + VSD or ASD
    + echogenic focus in left or right ventricle
  • mild renal dilation
    + pelviectasis also called pyelectosis
    + >/= 5 mm
  • duodenal atresia (double bubble)
  • tracheoesophageal fistula (increased FI)
  • shortened long bones (femur and humorous)
18
Q

less specific sonographic appearence trisomy 21

A
  • cystic hygroma = fluid back of babies neck
  • non immune hydros = fluid in cavities
  • clinodactyly = crooked fingers
  • echogenic bowel = same as heart
  • omphalocele
  • mild ventriculomegaly
  • sandal foot
19
Q

trisomy 18

A
  • Edwards syndrome
  • almost always lethal or very poor prognosis
  • 50% die in first two months
  • 90% die in first year
  • survivors have profound mental retardation
  • poor prognosis due to heart GI abnormalities
  • second most common at births
  • increases with LMA
  • triple screen markers all low
20
Q

trisomy 18 sonographic appearance

A
  • early onset of symmetric IUGR with polyhydroamnious
  • clenched fists and or clinodactyly
  • club feet or rocker bottom feet
  • CPCs - choroid plexus cysts
  • heart defects
    + large VSD most common
  • if CPCs are identified open hands need to be indentified
21
Q

trisomy 18 less specific signs

A
  • cleft lip or palate
  • omphalocele
  • diaphragmatic hernia
  • single umbilical artery
  • strawberry shaped head
  • radial ray syndrome (absent radius)
  • micrognathia (receding chin)
  • cystic hygroma
  • enlarged cisterna magna
22
Q

trisomy 13

A
  • patau syndrome
  • 70% are still born 85% die in first year
  • survivors have profound mental retardation
  • 3rd most common
  • increased risk with advanced maternal age
  • triple screen dos not detect trisomy 13
23
Q

T 13 sonographic appearance

A

-holoprosencephaly
+ severe abnormality of fore brain cleavage (cerebrum or prosencephalon)
+ fusion of cerebral hemispheres and thalami
+ 3 classifications
= lobar - mild
= semilobar
= lobar - severe

24
Q

lobar - holoprosencephaly

A
  • little or no cortical mantle
  • single horseshoe shaped ventricle
  • fused thalami and no 3rd ventricle or falx
25
Q

semilobar - holoprosencephaly

A
  • single horseshoe shaped ventricle with brain mantle

- no 3rd ventricle or falx

26
Q

lobar - holoprosencephaly

A
  • fused anterior horns that are squared off

- incomplete falx but 3rd ventricle may be seen

27
Q

T 13 more sonographic signs

A
  • cleft lip or palate
  • micropthalmia
  • hypotelorism
  • cyclopia
  • absent nose or replaced by proboscis
  • omphalocele
  • microcephaly or IUGR
28
Q

T 13 less specific indicators

A
  • polydactyly
  • clinodactyly
  • club feet
  • rocker bottom feet
  • cystic hygroma
  • severe heart defects
    + hypo plastic left heart
    + VSD
  • polycystic kidneys (echogenic kidneys)
  • enlarged cisterna magna
29
Q

triploidy

A
  • 69xxy 69xyy 69xxx
  • 60% fertilized with 2 sperm
  • 40% fertilization of a diploid (46 chromosome egg)
  • rare and usually lethal
  • hCG marked high (8x normal)
  • partial molar pregnancy
  • not associated with maternal age
30
Q

triploidy sonographic appearance

A
  • large placenta with cysts
    + only when fertilized with 2 sperm
    + termed partial mole
  • thin placenta when mother contributes the extra chromosomes
  • severest asymmetric IUGR and oligohydroamnios
31
Q

triploidy sonographic appearance

A
  • holoprosencephaly
  • agenesis of the corpus callosum
  • meningomyelocele
  • Arnold chiari malformation
  • ventriculomegaly
  • heart defects
  • facial clefts
  • syndactyly
  • club feet
  • cystic hygroma
  • omphalocele
  • thick placenta with cystic areas
  • severe asymmetric IUGR
32
Q

turners syndrome

A
  • 45Xo
  • missing one of the sex chromosomes
  • all are females
  • sterile = missing ovaries
  • maternal age not a factor
  • most common chromosome abnormality in spontaneous abortion however live born have few life threatening anomalies and normal intellect
  • 95% aborted
33
Q

turners syndrome sonographic appearance

A
  • cystic hygroma
  • hydrops
  • heart defects
    + coarctation of aorta
  • renal abnormalities
    + agenisis
    + horseshoe kidney
    + pelvic kidney
34
Q

cystic hygroma

A
  • separations wishing the fluid at back of neck

- web neck

Ob/Gyne (24 decks)

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