OBS: Fetal Medicine -- Abnormal Growth

Question 1

USG features for anencephaly

Answer 1

• “Frog eye” sign
• Absent cranium, no brain tissue
• Polyhyraminios

Question 2

What are some examples of neural tube defects?

Answer 2

Anencephaly, Spina bifida, Meningocele, Encephalocele, Hydrocephalus…

Question 3

How to counsel a couple having a fetus with ancephaly?

Answer 3

• Explain ancephaly (incidence: 1/2000 - 1/4000 birth)
• Cause: usually sporadic, possibly folate deficiency
• Consequence: not viable after birth
• Management:
  
  • 2nd trimester TOP
  • Grief counselling, psychological support
• Preparation for next pregnancy:
  
  1. Folate supplement
  2. Early morphology scan
  3. Prepare for 5-10% recurrence rate

Question 4

38 female, para 2, gestation 34 week referred for large for date. From overseas so no antenatal screening, 2 spontaneous deliveries (2.7kg and 3.2kg).

What are the reasons for referral?

Answer 4

Large for date, AMA, Investigations for causes

Question 5

What should be looked for in USG in a large-for-date fetus?

Answer 5

• Number of fetus
• Growth parameters, Estimated fetal weight
• Presentation
• Any abnormal morphology
• Placenta position, Liquor

Question 6

Biochemical test for large-for-date fetus

Answer 6

OGTT for GDM

Question 7

DDx for fetal head not engaging

Answer 7

• Cephalopelvic disproportion
• Macrosomia
• Obstructing fibroid
• Floating head due to polyhydramnios

Question 8

Normal range of AFI

Answer 8

8-24cm

Question 9

Diagnostic criteria of GDM

Answer 9

• Fasting glucose 5.1-7.0 mmol/L
• 1-hour OGTT >=10.0 mmol/L
• 2-hour OGTT 8.5-11.0 mmol/L

Question 10

Management of GDM

Answer 10

1. Specific for pre-gestational DM Folic acid until 12w gestation
2. Specific for gestational DM
   
   1. Refer to GDM class for education
   2. Arrange GDM clinic for FU
   3. Admission if FPG ≥ 6.5 mmol/L or diagnosed after 36w
3. General management
   
   1. Lifestyle modification:
      
      1. Singleton 1500kcal/day in 1st trimester, 1800kcal/day afterwards
      2. Regular exercise
      3. Home hstix monitoring
   2. Pharmaceutical treatment:
      
      1. Insulin
      2. PO Metformin

Question 11

What are the fetal structural abnormalities that may cause polyhydramnios?

Answer 11

• Esophageal atresia
• Duodenal atresia
• Anencephaly
• Omphalocele

Question 12

What congenital syndrome should you suspect when macrosomia and organomegaly are observed?

Answer 12

Beckwith-Wiedemann syndrome

Question 13

Diagnostic criteria of early onset FGR

Answer 13

• <32w, AND
  1. AC or EFW <3rd percentile, OR
  2. absent UmA EDF, OR
  3. AC or EFW <10th percentile + PI >95th percentile in UmA or UtA

Question 14

Management of early FGR

Answer 14

• Rule out dating problem
• Investigations for causes:
  
  • Chromosomal abnormalities: USG morphology, amniocentesis
  • Placental insufficiency: USG Doppler
  • Fetal infections: Toxoplasmosis Ab, CMV Urine sampling
  • APS: lupus anticoagulant, anticardiolipin Ab, anti-beta2 GP1 Ab
• If timing of delivery not optimal:
  
  • Fetal: stage FGR with USG monitoring weekly / twice weeking / daily according to staging
    
    • growth scan, liquor, umbilical artery, ductus venosus, middle cerebral artery PI
    • urgent delivery if UmA REDF, reverse a-wave in DV, pathological CTG
  • Maternal: BP + Urine dipstix every visit, HBPM
  • [<32w] MgSO4
  • [24-33w] Steroid
• Mode of delivery:
  
  • CS (if abnormal Doppler result, severe FGR, poor fetal well-being, immediate delivery required) or IOL
  • send cord blood gas analysis + placenta for workup

Question 15

T13 vs T18 in terms of hyper-/hypotelorism

Answer 15

T13: hypotelorism, T18: hypertelorism

Question 16

What is the quickest way to confirm T18?

Answer 16

PCR after amniocentesis [>16w] / CVS [>11w]

Question 17

Pros and cons of early vs delayed delivery for FGR

Answer 17

Early delivery:
- Pros: avoid IUD
- Cons: Prematurity risk
Delayed delivery:
- Pros: less prematurity risk
- Cons: IUD