O&G Written - Antenatal care

Question 1

Ways to estimate EDD?

Answer 1

Nagle’s rule: LMP - 3 months + 7 days + 1 year

• if cycle >28 days, add on the no. of days
• opposite if cycle <28 days

USS

• 11-13+6 week using Crown-rump length
• 14-20 weeks using head circumference

Question 2

Routine booking IX

Answer 2

Urine dip + culture
FBC
Antibody screen
Syphillis serology
Rubella IgG
HIV + Hep B testing offered
USS
\+/- Hb electrophoresis

Question 3

Folic acid supplementation advice

Answer 3

Should be started pre-conception + continued until 12 weeks gestation

Normally take 0.4mg/day

High risk take 5mg

• BMI > 30
• diabetes
• sickle cell disease
• malabsorption
• anti-epileptic medication

Question 4

Vitamin D supplementation advice

Answer 4

10 ug (400 units) for all women

25ug for high risk:

• BMI >30
• South Asian or Afro-Caribbean
• Low sunlight exposure
• Increased risk pre-eclampsia

Question 5

Role of 20 week USS

Answer 5

identify foetal abnormalities e.g., cardiac or renal defect

+/- cervical length assessment to identify pregnancy at risk of pre-term delivery

+/- uterine artery resistance measurement to identify at risk of growth restriction + pre-eclampsia

Question 6

Anti-D administration timeline

Answer 6

1st dose at 28 weeks

2nd dose at 34 weeks

Question 7

Combined test components

Answer 7

Nuchal translucency

b-hCG

PAPP-A

+ maternal age

Question 8

What does combined test screen for?

Answer 8

Trisomy 21 (Down’s syndrome)

+ Edwards (Tri18), Patau (Tri13)

Question 9

Components of triple & quadruple test?

Answer 9

Beta-hCG
Unconjugated oestradiol
Alpha feto protein

+ Inhibin A in quadruple

Question 10

possible in utero therapies

Answer 10

Anti-arrythmic ddrugs - flecainide, digoxin
NSAIDs for polyhydramnios

Laswer tx for twin-twin transfusion syndrome
Amnioreduction for polyhydramnios
Pleuroamniotic shunt for hydros / effusions
Vesicoamniotic shunt for urethral valve
Blood & platelet transfusion
Tracheal occlusion for diaphragmatic hernia (stimulates lung growth)
Valvoplasty for critical aortic stenosis
Cord occlusion for mono chorionic twins

Open NTD surgery

Question 11

Timing of amniocentesis

Answer 11

Done from 15-20 weeks

Question 12

Timing of chorionic villus sampling

Answer 12

Between 11-13+6 (10-15 weeks)

Technically can be done up until end of pregnancy

Question 13

Miscarriage rate in invasive diagnostic testing

Answer 13

Amniocentesis = 1%

Chorionic villus sampling may be slightly higher but is done earlier when baseline spontaneous miscarriages are more common

Question 14

Cut off for high risk of Down’s syndrome in Combined test?

Answer 14

> 1 in 150

Go on to have non invasive cell free foetal DNA +/- invasive diagnostic testing