Antenatal Screening

Question 1

What % of women deliver on their due date?

Answer 1

4%

Question 2

What % of women will deliver within one week either side of their due date?

Answer 2

60%

Question 3

What basic investigations are carried out at the booking visit?

Answer 3

Hb
ABO - Rhesus
STD screening (HIV, Hep, Syphillis) 
Urinalysis
USS
Confirm viability of pregnancy 
Estimate gestational age

Question 4

An empty sac is an ________ until proven otherwise

Answer 4

Ectopic pregnancy

Question 5

What % of foetal heart defects are picked up in screening/

Answer 5

60%

Question 6

Major structural abnormalities occur in __% of pregnancies?

Answer 6

2-3%

Question 7

What genetic abnormality is found in Patau’s syndrome

Answer 7

Trisomy of c13

Question 8

What is placenta previa

Answer 8

This is when the placenta lies low in the womb, covering most, if not all of the cervix.

Question 9

What should be done if 18+0 r 20+6 scans show placenta previa?

Answer 9

Rescan at 32 weeks

If abdo exam unclear, offer vaginal scan

Question 10

What do you test in the first trimmest to assess Down’s Risk and how do you do it?

Answer 10

Skin thickness of fetal neck

USS - nuchal thickness

Question 11

When is nuchal thickness screened for?

Answer 11

11-13 weeks

Question 12

What is considered a normal skin thickness

Answer 12

<3.5mm when crown rump length is between 45-84 mm

Question 13

What screening tests are done in second trimester for Downs?

Answer 13

Blood sample for assay of HCG and AFP

Question 14

What gestational age is blood test sampling for Down’s carried out

Answer 14

15-20 weeks

Question 15

When would amniocentesis be offered?

Answer 15

If a woman’s risk is greater than 1:250

Question 16

What screening options are available if a woman misses first trimester screening?

Answer 16

Mid trimester screening from w15-20+6

Question 17

If a woman attends the first trimester screening, is it necessary to offer the mid trimester screen?

Answer 17

No

Question 18

What tests are done at the id trimester screening?

Answer 18

Maternal age + biochemical markers = risk assessment

Biochemical markers:
AFP
hCG
unconjugated oestradiol
inhibin A

Question 19

How are the biochemical markers measured?

Answer 19

Specific immunoassay methods

Question 20

What non invasive prenatal test can identify women with an increased risk of certain genetic and chromosomal conditions?

Answer 20

Cell free foetal DNA testing

aka non invasive prenatal testing

Question 21

When is amniocentesis carried out?

Answer 21

After 15 weeks

Question 22

What is the risk of miscarriage following amniocentesis testing/

Answer 22

1%

Question 23

When is chorionic villous sapling carried out?

Answer 23

After 12 weeks GA

Question 24

What is the miscarriage rate in chorionic villous sampling?

Answer 24

2%

Question 25

What risk factors would mean you should offer a test for gestational diabetes?

Answer 25

- BMI >30 - Previous macrosomic baby - Previous GD - FHx of diabetes - Minority ethnic family origin with high prevalence of DM

Question 26

What test is done for at risk women, for gestational diabetes?

Answer 26

2 hour 75g oral glucose tolerance test

Question 27

What results would be diagnostic of gestational diabetes?

Answer 27

Fasting plasma glucose of 5.6mmol/litre or above OR 2 hour plasma glucose level of 7.8 mmol/litre or above

Question 28

What measurement is recommended from week 24, to predict potential SGA?

Answer 28

Symphysis - fundal height

Question 29

When would women be referred for foetal sizing by USS?

Answer 29

BMI >35 Large fibroids Hydramnios (basically anything that makes it hard to measure SFH)

Question 30

What medication should be given to women at high risk for pre-eclampsia?

Answer 30

75mg aspirin daily from 12w until birth

Question 31

What risk factors would make a woman 'high risk' for pre-eclampsia?

Answer 31

``` Chronic kidney disease Hypertension in previous pregnancy Diabetes T1 or 2 Chronic hypertension Autoimmune diseases e.g. SLE or antiphospholipid syndrome ```

Question 32

What risk factors would be considered moderate risk for pre-eclampsia?

Answer 32

``` >40y/o First pregnancy BMI >35 FHx of preeclampsia Multiple pregnancy Pregnancy interval >10years ```

Question 33

When should you offer an OGTT for a woman with mild risk factors for gestational diabetes?

Answer 33

Weeks 24-28

Question 34

If a woman has had gestational diabetes in past pregnancies, what is the appropriate screening procedure?

Answer 34

OGTT as soon as they book their first visit If that's normal Recheck at 24-28 weeks

Question 35

What is the combined test?

Answer 35

This is when the mother goes for screening weeks 11-13 and it involves a blood test and an ultrasound scan

Question 36

When would a triple/quadruple test be performed?

Answer 36

If the woman misses the 11-13 week screening | Can be performed from weeks 15-20

Question 37

What does the triple test incorporate?

Answer 37

Serum alpha fetaprotein, bHCG and oestriol.

Question 38

What is included in the quadruple test?

Answer 38

``` Usually weeks 15-16 AFP hCG unconjugated oestradiol inhibin A ```