Twin Gestations

Question 1

Rate of twins

Answer 1

1: 30 births

3. 3% of all live births

Question 2

If monozygotic twins cleave in first 0-4 days after fert you get

Answer 2

Dichorionic diamniotic twin
Di/Di

2 morula –> 2 blastocysts in own layer of trophoblast cells –> own chorion –> own amnion

Question 3

If monozygotic twins cleave in 4-8 days after fert you get

Answer 3

monochorionic diamniotic twin
Mo/Di

*most common of the monozygotic twins (75%)

Question 4

If monozygotic twins cleave in 8-12 days after fert you get

Answer 4

monochorionic monoamniotic twin

Mo/Mo

Question 5

How many twin pregnancies are conceived spontaneously?

Answer 5

50%

Question 6

Risk of twin pregnancies (12)

Answer 6

1. Miscarriage
2. Hyperemesis (high hCG)
3. high risk of aneuploidy and anomalies
4. Prenatal screening tests less sensitive and diagnostic procedures more difficult
5. Maternal anemia
6. Gestational diabetes ( high hPL)
7. Gestational hypertension/preeclamsia
8. Intrauterine growth restrictions
9. Preterm birth (~36 weeks)
10. Higher rate of Cesarean delivery
11. Postpartum hemorrhage
12. High perinatal mortality (first week)

Question 7

Twin twin transfusion syndrome

• what is it?
• What does the recipient twin do?
• What does the Donor twin do?

Answer 7

20% of mo-di twins have unbalanced flow through connected vessels

1. Recipient twin (larger)
   - increases urine production to reduce blood volume
2. Donor twin (smaller)
   - Reduces urine production to retain blood volume

Question 8

When do you have to treat TTTS by?

Answer 8

Prior to 24 weeks or else mortality of one or both twins in 80-90% of cases

Question 9

WHAT causes death of donor twin

Answer 9

decreased blood vol –> lower Urinary output to maintain blood vol –> oligohydramnios –> shunt away nutrients and cant support fetal growth

Question 10

What causes death of recip twin

Answer 10

getting too much bv –> huge strain on babys heart (HF) –> too much urine prod –> polyhydramnios –> uterine distention and early deliver
- sometimes fetal hydrops

Question 11

Twin peak/ Lamda sign = ?

Answer 11

Thick dividing membrane = DI Di

- 0-4 days

Question 12

T sign ?

Answer 12

MO/DI

- 4-8 days

Question 13

TTTS, which twin is smaller, which is larger?

Answer 13

Recipient twin is larger

DOnor twin is smaller

Question 14

TTTS most common in which twins?

Answer 14

Mo-Di