Prenatal screening

Question 1

Ultrasound scans dates

Answer 1

• Dating scans take place 7 - 12 weeks gestation - Nuchal translucency 10 - 14 weeks - Fetal anomaly in detail 18 - 22 weeks

Question 2

What investigations are done at the booking visit?

Answer 2

1. FBC
2. Blood group
3. Resus status
4. Blood pressure, Urine dipstick and BMI

Question 3

Amniocentesis

Answer 3

• transabdominal aspiration of amniotic fluid - determine karyotype of amniocytes - Performed 15 weeks to 16 weeks - Anti D is given to rhesus negative women

Question 4

Flourescent insitu hybridization / Polymerase Chain reaction

Answer 4

• faster results within 24 - 72 hours can be obtained using these methods - preliminary results provided and need to be confirmed by a culture

Question 5

Chorionic villous sampling

Answer 5

1. Biopsy of chorionic villi under continous ultrasound guidance 2. Examine a sample of cells to determine their genetic make up 3. Performed from 11 weeks onwards

Question 6

Fetal blood sampling

Answer 6

1. Transabdominal needle aspiration of blood from the fetal hepatic vein /umbilical chord 2. This allows diagnosis of ; fetal anaemia/chromosomal abnormalities/fetal thrombocytopenia/fetal infections 3. Used for treatment of fetal conditions - transfusions

Question 7

Nice recommended visits

Answer 7

10 antenatal visits in the first pregnancy if uncomplicated 7 antenatal visits in subsequent pregnancies if uncomplicated women do not need to be seen by a consultant if the pregnancy is uncomplicated

Question 8

8 - 12 weeks (ideally < 10 weeks)

Answer 8

1. Booking visit -general information e.g. diet, alcohol, smoking, folic acid, vitamin D, antenatal classes - BP, urine dipstick, check BMI - Booking bloods/urine - FBC, blood group, rhesus status, red cell alloantibodies, haemoglobinopathies - hepatitis B, syphilis, rubella - HIV test is offered to all women - urine culture to detect asymptomatic bacteriuria

Question 9

10 - 13 weeks

Answer 9

Early scan to confirm dates, exclude multiple pregnancy

Question 10

11 - 13 weeks

Answer 10

Down’s syndrome screening including nuchal scan

Question 11

16 weeks

Answer 11

Information on the anomaly and the blood results.

If Hb < 11 g/dl consider iron

Routine care: BP and urine dipstick

Question 12

18 - 20 weeks

Answer 12

Anomaly scan

Question 13

25 weeks (only if primip)

Answer 13

Routine care: BP, urine dipstick, symphysis-fundal height (SFH)

Question 14

28 weeks

Answer 14

Routine care: BP, urine dipstick,

SFH

Second screen for anaemia and atypical red cell alloantibodies.

If Hb < 10.5 g/dl consider iron

First dose of anti-D prophylaxis to rhesus negative women

Question 15

31 weeks (only if primip)

Answer 15

Routine care - BP, urine dipstick,

symphysis-fundal height (SFH)

Question 16

34 weeks

Answer 16

Routine care as above

Second dose of anti-D prophylaxis to rhesus negative women*

Information on labour and birth plan

Question 17

36 weeks

Answer 17

Routine care as above

Check presentation - offer external cephalic version if indicated Information on breast feeding,

vitamin K,

‘baby-blues’

Question 18

38 weeks

Answer 18

Routine care as above

Question 19

40 weeks - primip only

Answer 19

Routine care as above Discussion about options for prolonged pregnancy

Question 20

41 weeks

Answer 20

Routine care as above Discuss labour plans and possibility of induction

Question 21

When should the booking visit be done

Answer 21

8 - 12 weeks

(ideally < 10 weeks)

Question 22

What diseases are screened for at the booking visit?

Answer 22

1. Hepatitis B
2. Syphilis
3. Rubella
4. HIV test offered to women
5. Urine culture to detect asymptomatic bacteriuria

Question 24

Antenatal visits in first pregnancy

Answer 24

10

Question 25

Number of antenatal visits in subsequent pregnancies if first is uncomplicated

Answer 25

7

Question 26

Supplements advised to be given to women at the booking visit

Answer 26

1. Folic acid 400 mcg (before conception to 12 weeks) - reduce risk of neural tube defects

2.

2. Vitamin D supplements 1- mcg a days

Question 27

Things to be avoided during pregancy

Answer 27

1. Vitamin A supplements - Liver is high in vitamin A and high amounts can be teratogenic
2. Stop smoking and drinking
3. Avoid unpateurised milk + soft cheese - listeriosis
4. Avoid all prescribed medicines unless harm outweighs benefit

Question 29

Which two tests are used antenatal testing of down’s syndrome

Answer 29

1. Combined test (11 - 13 weeks)
2. Triplet /Quadruple test - (15 - 20 weeks)

Question 30

What does the combined test for Down’s syndrome involve?

Answer 30

1. Nuchal transluscency measurement
2. Beta HCG
3. Pregnancy associated plasma protein A

Question 31

Triplet / Quadruplet testing for Down’s syndrome

Answer 31

1. 15 - 20 weeks

Alpha-fetoprotein

Unconjugated Oestriol

Beta HCG

+/- Inhibin A

Question 32

What circumstances is Alpha feto bprotein raised in

Answer 32

1. Neural tube defects
2. Abdominal wall defects - omphalocele
3. Multiple pregnancy

Question 33

Causes of decreased AFP

Answer 33

1. Down’s syndrome
2. Maternal diabetes mellitus