Aneuploidy screening

Question 1

Likelihood of chromosome anomalies
Age 20
30
40

Most common sex chromosome aneuploidy

The only viable monosomy

Answer 1

1/122
1/110
1/40

Klinefelter syndrome 47 XXY

Turner syndrome 45X

Question 2

First trimester screen

Timing
Detection rate
Serum markers tested

Answer 2

10-13+6

85%

NT, PAPP A, HCG

Question 3

Quad screen

Timing
Detection rate
Serum markers

Answer 3

15-22w
81%
HCG, unconjugated estriol , DImeric inhibin, AFP

Question 4

Integrated

Answer 4

First trimester PAPP-A and Quad

96%

Question 5

NT alone

What’s abnormal

Answer 5

10-13+6

70%

> 3.0 mm

Question 6

Causes of false positive CFDNA

Answer 6

Placental mosaicism
Malignancy
Vanishing twin

Question 7

Cystic hygroma

Answer 7

Accumulation of lymphatic fluid in fetal neck

50% are aneuploid

Associates with Turner synd, T21, T18

Question 8

Absent or hypoplastic nasal bone

Answer 8

Absent in 30-40% with Down syndrome

Hypoplastic in 50-60% w Down synd

Question 9

Pyelectasis >4mm

Answer 9

T 21

Question 10

Echogenic bowel

Answer 10

T21
IUGR
CF
CMV

Question 11

Mild to moderate ventriculomegaly

10-15 mm

Answer 11

T21 or infection

Question 12

Short femur length

Answer 12

Aneuploidy
iUGr
Skeletal dysplasia

Question 13

EIF

Answer 13

15-30% of fetuses with T21

Question 14

Chorioid plexus cyst

Answer 14

T 18

Question 15

First trimester PAPP A <5%ile

Can indicate increased risk of

Answer 15

PreE
IUGR
abruptiin
PtB
Fetal and neonatal loss

Question 16

Most common sex chromosome aneuploidy

mC monosomy

Answer 16

47 XXY

45 X0

Question 17

Elevated AFP and low Papp A in the setting of normal Karyotype indicate increased risk of

Answer 17

IUGR
IUFD
PTL

AFP indicates increased risk of SIDS up to 6 mo GA