OBS: Antenatal Care -- Thalassaemia

Question 1

DDx of low MCV and further investigations

Answer 1

DDx: iron deficiency anaemia, anaemia of chronic disease, sideroblastic anaemia (e.g. lead poisoning), thalassaemia (carrier)
Ix:
1. Serum ferritin, Hb pattern
2. (for alpha) blood film, immunochromatographic strip, (for beta) HPLC
3. alpha genotyping

Question 2

Diagnosis of beta-thalassaemia trait

Answer 2

HPLC: HbA2 >3.5%

Question 3

How to counsell a couple who are both alpha thalassaemia carriers?

Answer 3

Explain the probability for fetus to be alpha thalassaemia major is 25% (assuming SEA deletion)
Prenatal diagnosis can be made in future pregnancies:
1. Ultrasound Q2w in 12~24w for fetal anaemic features
a. cardiothoracic ratio (>0.5) (90% sensitivity at 12~15w)
b. increased placental thickness
c. increased MCA PSV
2. CVS / Amniocentesis
3. Cordocentesis
Consider IVF with pre-implantation genetic diagnosis
Take 5mg folic acid throughout pregnancy

Question 4

What is the most common genotype for alpha thalassaemia trait?

Answer 4

SEA deletion

Question 5

Implication of hydrops fetalis to mother

Answer 5

increased chance of PET

Question 6

How to prevent alpha thalassaemia in next pregnancy?

Answer 6

IVF followed by pre-implantation genetic analysis, transfer of unaffected embryos

Question 7

What are the management options for confirmed alpha thalassaemia? Pros and Cons?

Answer 7

1. Non-aggressive approach:
   (Before 24w) TOP
   (After 24w) Early IOL to induce preterm birth without neonatal resuscitation
   Pros: reduce risk of PET, reduce risk of obstructed labour due to hydrop, no complications of treatment
   Cons: fetus not viable
2. Aggressive approach:
   a. Repeated in-utero transfusion Q2~4w
   b. Post-natal regular transfusion / BM transplant
   Pros: fetus kept alive
   Cons: risk of neurodevelopmental delay, hypoxic anatomical abnormalities

Question 8

EIA and VDRL +ve. What are the further tests? How do they affect the management?

Answer 8

Specific Treponemal Diagnostic Tests: FTA-abs, TPPA
If -ve, EIA & VDRL are false positives
If +ve & not treated before, diagnosed as latent syphilis. Treat with IM Penicillin

Question 9

Risk factors for transverse fetal lie

Answer 9

Maternal: multiparity (lax uterus), lower segment obstructed by SOLs
Obstetrics: multiple pregnancies, polyhydramnios, PROM when fetal is in transverse lie
Fetal: Fetal abnormalities

Question 10

Complications of ECV

Answer 10

Transient fetal decelleration after ECV
Acute fetal distress
Placental abruptio
Rupture of membrane