PB 144: Multifetal Gestations: Twin, Triplet, and Higher-Order Multifetal Pregnancies

Question 1

Fetal and Infant Morbidity and Mortality: Statistics

Answer 1

Question 2

How is chorionicity determined?

Answer 2

When ultrasound assessment clearly shows two placentas or differing fetal sex, the pregnancy is dichorionic.

If only one placenta is visualized, the best ultrasonographic characteristic to distinguish chorionicity is the twin peak sign (also called the lambda or delta sign). It is a triangular projection of tissue with the same echogenicity as the placenta that extends beyond the chorionic surface of the placenta and is indicative of a dichorionic gestation.

Question 3

Are there interventions that can prolong pregnancy in women with multifetal gestations?

Answer 3

Interventions, such as prophylactic cerclage, routine hospitalization and bed rest, prophylactic tocolytics, and prophylactic pessary, have not been proved to decrease neonatal morbidity or mortality and, therefore, should not be used in women with multifetal gestations.

Question 4

Corticosteroid management in multifetal gestations?

Answer 4

One course of antenatal corticosteroids should be administered to all patients who are between 24-34 weeks of gestation and at risk of delivery within 7 days, irrespective of the fetal number.

Question 5

What is considered discordant fetal growth?

Answer 5

20% difference in EFW between the larger and smaller fetus

Growth discordance ratio:

the difference in EFW between the two fetuses / EFW of the larger fetus

Question 6

How are the complications caused by monochorionic placentation managed?

Answer 6

Twin–twin transfusion syndrome:

Occurs in approximately 10–15% of monochorionic–diamniotic pregnancies

Results from: presence of arteriovenous anastomoses in a monochorionic placenta. In the affected pregnancy, there is an imbalance in the fetal–placental circulations, whereby one twin transfuses the other. It usually presents in the second trimester, and serial ultrasonographic evaluation approximately every 2 weeks beginning at approximately 16 weeks of gestation should be considered

Question 7

How is Twin-Twin Tranfusion Syndrome diagnosed?

Answer 7

Monochorionic–diamniotic twin gestation with oligohydramnios (MVP < 2 cm) in one sac and polyhydramnios (MVP > 8 cm) in the other sac

Question 8

Staging for TTTS

Answer 8

Question 9

What should be the MOD for mono-mono twins? Why?

Answer 9

C/S due to risk of cord entanglement

Question 10

Timing of delivery for multifetal gestation:

Answer 10

• Uncomplicated di-di: 38 w
• Uncomplicated mono-di: 34-37 6/7 w
• Uncomplicated mono-mono: 32–34w (via C/S)

Question 11

Summary of Recommendations and Conclusions: Level A

Answer 11

• No role for the prophylactic use of any tocolytic agent in women with multifetal gestations, including the prolonged use of betamimetics for this indication.
• Progesterone treatment does not reduce the incidence of spontaneous preterm birth in unselected women with twin or triplet gestations and, therefore, is not recommended.

Question 12

What is the optimal timing for determination of chorionicity?

Answer 12

Determination of chorionicity by U/S should be performed late in the first trimester or early in the second trimester

Question 13

What are two main factors that have led to an increase incidence in the number of multifetal gestations?

Answer 13

1. Older maternal age at conception, when multifetal gestations are more likely to occur naturally
2. Increased use of ART