Obstetrics - Routine antenatal care

Question 1

Booking visit for antenatal care
- Function
- Timing
- Reason for timing

Answer 1

Booking Visit
- The initial contact with community midwife to for hx taking, PE and Ix for appropriate care and early referral
- Timing - ~10-14w
○ Not earlier because a lot of early pregnancies are lost
○ Not later to facilitate 1st trimester Down syndrome screening (before 13+6) and accurate dating (CRL up to 13+6)

Question 2

Symptoms and tests for confirmation of pregnancy

Answer 2

Symptoms of pregnancy
- 2o amenorrhoea with background Hx of regular menstrual cycle
- Nausea and vomiting: commonly occur ≤6w-3mo, can occur any time of day and ppt by smell/sight of food due to hCG,
- ± hyperemesis gravidarum (severe, persistent V → dehydration, ketonuria, electrolyte imbalance)
- ↑urinary frequency: due to pressure on bladder exerted by gravid uterus (Diminishes ≤12w)
- Excessive lassitude or lethargy - usually disappears after 12w
- Breast tenderness and heaviness: due to extension of premenstrual phase of cycle, due to ↑progesterone + ↑retention of water
- Fetal movements - usu not noticed until 20w (primi) or 18w (multi)
- Pica

Tests:
- Urinary / serum hCG: detectable 6d after ovulation, usu test +ve from 4w (around missing period)
- ± USG: below TVUS dates, TAUS a bit later
○ Fetal sac - visible 4.5-5w
○ Yolk sac - 5-6w to 10w
○ Fetal pole with cardiac activity - 5.5-6w

Question 3

Dating pregnancy

• Purpose
• Definition of gestational age
• Definition of Estimated date of Confinement/ Delivery (EDC/ EDD)

Answer 3

Question 4

Dating pregnancy
- Methods of dating

Answer 4

Dating by LMP - LMP + 280d or LMP + 9mo + 7d (Naegele’s rule)
- If cycle >28d, then add (cycle length - 28d)

Ultrasound dating - recommended for all women, ideally between 10-14 weeks but not routinely done in HK
- Calculation: by plotting on standard fetal biometry charts with measurements of
- Crown-rump length (CRL) - before 13wk + 6d
- Head circumference (HC) - 14-20 wk

Dating by assisted reproductive technology (ART) - fertilization + 266d

Question 5

Comparative advantages and disadvantages of dating by LMP vs dating by ultrasound scan

Answer 5

Question 6

Outline history taken during booking visit

Answer 6

Question 7

Outline booking visit examination and first-line investigations

Answer 7

Question 8

Outline the timing for antenatal care

Answer 8

1. Pre-pregnancy visit
2. Booking (10-14w)
3. First visit (Follow-up every 6 weeks before 24 weeks if normal)
4. 1st trimester Down Syndrome screening (11-13w +6w)
5. Chorionic villus sampling if indicated (10-12w)
6. 75g early OGTT for high risk GDM (10-16w)
7. 2nd trimester Down Syndrome screening (16-19w)
8. Amiocentesis if indicated (18w)
9. Anomaly scan (18-20w, Follow-up every 4 weeks at 24-30weeks if normal)
10. 75g routine OGTT for low risk or Repeated OGTT for high risk patients (28-32w, Follow-up every 2 weeks at 30-36 week if normal)
11. GBS screening (35-37w)

Question 9

Outline investigations done at first visit

Answer 9

Question 10

Outline investigations at 10-18w

Answer 10

Question 11

Outline investigations at 20w

Answer 11

Question 12

Outline investigations at 30w

Answer 12

Question 13

Outline investigations at 36w

Answer 13

Question 14

Lifestyle modifications during antenatal period

• Diet
• Exercise
• Coitus
• Breast care
• Drug use

Answer 14