Obs - congenital abnormalities

Question 1

what are the characteriistics of a good screening test?

Answer 1

 Cheap

 High sensitivity
o Proportion of subjects with the condition who screen positive for the condition

 High specificity
o Proportion of subjects without the condition who are classified as screen negative

 Safe

 Acceptable diagnostic test for the disorder for which it is screening

Question 2

what are the methods of prenatal testing in the mother?

Answer 2

Maternal blood test

Ultrasound

FMRI

3D/4D US

AMniocentesis

CVS

PGD - pregenetic diagnosis

Question 3

what does increased maternal blood afp tell us?

Answer 3

neural tube defects: increased afp

gastrochisis : increased afp

not used much - US used instead

Question 4

what is the nuchal translucency?

normal range?

Answer 4

fluid-filled subcutaneous space identified at the back of the fetal neck during the late first trimester and early second trimester

approx less than 3.5mm

Question 5

all abnormlaities are picked up on the anomaly scan at 20 weeks. true/false

Answer 5

false

some may develop later eg cardiac abnormality

Question 6

use of fmri in pregnancy?

Answer 6

intracranial lesions

soft tissue differentiation

Question 7

how would one ivx prenatally for cmv, toxoplasmosis, and inherited conditions eg thalassaemia?

Answer 7

Amniocentesis

Question 8

risks of amniocentesis?

Answer 8

1% miscarriage chance

infection

Question 9

how can chromosomal abnormalities be tested for?

Answer 9

Amniocentesis + FISH/PCR

CVS - (biopsy of the trophoblast) + FISH/PCR

• tests for AD/AR conditions
• higgher miscarriage rate tham amnio

Question 10

what are the conditoins for pre implantation genetic diagnosis to be done?

What can be tested for?

Answer 10

need to do IVF

sex linked, trismoies, AD/AR

Question 11

What are the trismoies and associated syndromes?

Answer 11

21, 18, 13
D, E, P

downs, Edwards, patau

Question 12

what causes trisomies?

Answer 12

non-dysjunction during meiosis

6% balanced chromosal translocation

Question 13

what are the rsik factors for downs syndrome ?

maternal, US, bloods

Answer 13

Maternal:
increased age, previous affected baby

Ultrasound:
thickened n translucency,
Absent/short nasal bone
Tricuspid regurgitation

Bloods:
Low PAPP-A (1st tri)
Low AFP (1st/2nd)
Low oestriol (2nd)
High inhibin (2nd)
High B-hCG (1st/2nd)

Question 14

what are diagnostic test for trismoies?

Answer 14

amniocentesis and cvs

so everything listed in risk factor is just rf, not decisive.

Question 15

what tests are done fore screening on downs syndrome?

Answer 15

1. COMBINED TEST:
risk from maternal age
 PAPP-A - blood test
 B-hCG - blood test
Nuchal scan - nuchal translucency ( 11-13+6 weeks)

2. Triple test - done if screening was done late (>14wks)
o AFP
o hCG
o Oestriol
- done at 16 weeks. less accurate

Amniocentesis, CVS - daignostic tests - not screening

Question 16

how does anencephaly present

Answer 16

Absence of cranium - parts fo brain, skull and scalp

Frog Eye appearance on USS

Incompatible with life

Question 17

what can be done about NTD in utero?

Answer 17

open surgery can reduce disability

Question 18

how do cardiac abnormlaities present?

rx?

Answer 18

50% enlarged nuchal translucency

rx: in utero rx of arrthymia (with drugs).
valvoplasty - aortic stenosis

Question 19

name some abdominal structural abnormalities? - defects in abdominal wall

rx?

Answer 19

Exomphalos ? Omphalocele - extrusion of abdominal contents but remains in a sac. good prognosis

Gastrochissis - free loops of bowel in amniotic cavity. good prognosis. surgery post fatally

Question 20

what are the complications of pleural effusions in pregnancy?

Answer 20

hydros fetalis

Question 21

list some causes of hydrops fetalis?

Answer 21

Non immune:
Twin–twin transfusion syndrome
Chromosomal abnormalities
Structural abnormalities - e.g. pleural effusions
Cardiac abnormalities or arrhythmias
Anaemia - causing cardiac failure

Immune:
Anaemia + Haemolysis - Alpha thalasaemia, parvovirus
Result of rhesus disease or ABO mismatch

Question 22

treatment for hydrops?

Answer 22

depends on cause:

anaemia - blood transfusion

pleural effusion - pleuroamniotic shunt

Twin–twin transfusion syndrome - laser ablation

otherwise untreatable!

Question 23

the double bubble sign is indicative of?

Answer 23

dilated upper stomach

often seen in Down’s

Question 24

GI structural defects often lead to?

Answer 24

Polyhydramnios

Question 25

what is the most common cause of hydrops in early pregnancy?

Answer 25

chromosomal abnormalities particularly tri 21 - Down’s

Question 26

how would you investigate suspectef hydrops?

Answer 26

1st line:
US
Echocardiography
MCA doppler

Others:
Maternal blood - kleihauer, infection
Fetal blood sampling if anaemia is suspected
Amniocentesis - karyotype, infectious causes

Question 27

name a medical therapy for polyhrdamnios?

Answer 27

NSAIDs