Antepartum care

Question 1

Causes of bHCG less than expected

Answer 1

Ectopic pregnancy
Miscarriage
Inaccurate dates

Question 2

Causes of bHCG greater than expected

Answer 2

Multiple pregnancy
Molar pregnancy
Trisomy 21
Inaccurate dates

Question 3

When is gestational sac visible on U/S

Answer 3

4-5 weeks

Question 4

What is Naegele’s rule for calculating EDD?

Answer 4

1st Day of LMP + 7 days, - 3 months + 1 year

add days if cycle >28d long

Question 5

5 questions to ask to calculate EDD

Answer 5

First day of LMP?
Was this period normal in all respects?
Menstrual cycle regular?
Menstrual cycle length?
Are you using contraception?

Question 6

What gestation is most accurate for calculation of EDD by ultrasound

Answer 6

7-10 weeks (EDD calculated +/- 3 days)

Question 7

How much folic acid should a woman take if pregnant?

Answer 7

400ug until 12 weeks gestation

5mg if previous pregnancy affected by neural tube defects or FHx

Question 8

Virus/bacteria exposures tested for on 1st visit bloods

Answer 8

Rubella titre
Syphilis serology
Hepatitis B
Hepatitis C
HIV

Question 9

When is morphology scan done

Answer 9

18-20 weeks gestation

Question 10

If mother Rh-, when is prophylactic anti D given?

Answer 10

625IU given at 28 and 34 weeks and post delivery

Question 11

In what other circumstances would you give anti-D

Answer 11

Threatening miscarriage
ectopic pregnancy
D&C 
Amniocentesis
Termination of pregnancy
Antepartum haemorrhage
Abdominal trauma
External cephalic version

Question 12

How much anti-D do you give in the first trimester

Answer 12

250IU

Question 13

When do you do a OGTT in low risk women?

Answer 13

28 weeks

Question 14

When do you do a lower vaginal swab for Group B streptococcus

Answer 14

36 weeks

Question 15

What glucose levels are diagnostic of gestational diabetes

Answer 15

Fasting venous glucose ≥ 5.0 mmol/L

2h venous glucose ≥ 6.7 mmol/L

Question 16

What risk factors does a woman need to have to be “high risk” for GDM?

Answer 16

Previous GDM
Maternal age ≥ 40
BMI ≥ 35
Previous baby >4.5kg or >P90
Polycystic ovarian syndrome

Question 17

What are the 3 screening tests for fetal aneuploidy

Answer 17

1. First trimester combined
2. Second trimester
3. Non-invasive prenatal testing (NIPT)

Question 18

What are the 2 diagnostic tests for fetal aneuploidy

Answer 18

1. Chorion villus sampling

2. Amniocentesis

Question 19

What is measured in combined first trimester screening test?

Answer 19

1. free bHCG
2. PAPP-A (pregnancy associated plasma protein)
3. Nuchal translucency U/S at 11-13+6 weeks

Question 20

What is measured in second trimester screening (when GA 14-20+6)

Answer 20

1. Alpha fetoprotein
2. bHCG
3. Unconjugated estriol

Question 21

What does the NIPT involve?

Answer 21

Maternal plasma used to collect cell-free fetal DNA
Can assess T18. T21, T9 plus sex hormones
Done >10 weeks

Question 22

When is chorion villus sampling done?

Answer 22

10-14 weeks

Question 23

When is amniocentesis done?

Answer 23

> 14 weeks

Question 24

What is the risk of miscarriage with the 2 diagnostic tests?

Answer 24

CVS: 0.5-1%
Amniocentesis: 0.5%