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
2
Q
euploidy
A
- means good set
3
Q
trisomy
A
- one extra complete or partial chromosome (47XY)
- 21, 18, 13
4
Q
triploidy
A
- a complete extra set of chromosomes (69 XXY)
- form of polyploidy
5
Q
monosomy turners syndrome
A
- 45Xo
- missing an X or Y from paternal (fathers) side
- always female
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
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
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
9
Q
quad screen elements
A
- AFP
- EU
- hCG
- Inhibin A
10
Q
AFP
A
- alpha-fetoprotein
- produced by fetal liver
11
Q
EU
A
- unconjugated estriol
- produced by fetal liver and placenta
12
Q
hCG
A
- human chorionic gonadotropin
- produced by the placenta
13
Q
Inhibin A
A
- hormone produced by the placenta
14
Q
triple screen - trisomy 21
A
- MSAFP decreases
- B hCG increases
- UE3 decreases
- inhibit A increases
15
Q
triple screen - trisomy 18
A
- MSAFP decreases
- B hCG decreases
- UE3 decreases
- inhibin A doesnt change
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
