Monochorionic Diamniotic Twin Gestations

Question 1

What pregnancy complications are unique to monochorionic twins compared to dichorionic twins?

Answer 1

TTTS (centered vessels) TAPS (peripheral vessels) sFGR TRAP Monoamniotic twins Conjoined twins Discordant anomalies High-order monochorionic multiples Death of one twin

Question 2

Describe ultrasound features characteristic for a mo/di twin gestation.

Answer 2

T sign Thickness of intertwin membranes < 2 mm 2 layer of membranes (amnion and amnion) Single placenta Concordant gender

Question 3

How do you follow a mo/di twin during pregnancy?

Answer 3

11-14 weeks Dating, chronicity, screen 16-18 weeks Growth, DVP, UA-PI 20 weeks Anatomy, Growth, DVP, UA-PI, MCA-PSV and CL US every 2 weeks for growth, DVP, UA-PI and MCA-PSV

Question 4

When do you recommend delivery in an uncomplicated monochorionic twin gestation?

Answer 4

34 weeks and 37 6/7 weeks of gestation

Question 5

How do you counsel a patient about risks following a monochorionic cotwin demise in the first trimester?

Answer 5

The risk of death in the co-twin is 15% in monochorionic gestations and 3% for dichorionic gestations. The risk of neurologic abnormality in the surviving twin is greater in monochorionic gestations (18%) versus dichorionic gestations (1%)

Question 6

If an intertwin diving membrane cannot be visualized, what is your differential diagnosis?

Answer 6

Monoamniotic twin Conjoint twin Rupture of membrane Poly/oli sequence

Question 7

placental features of selective fetal growth restriction in monochorionic twins

Answer 7

• unequal sharing of placenta
• eccentric cord insertion in the growth restricted baby
• A-A anastamosis as compensatory for the growth restricted twin to get more flow

Question 8

How is selective growth restriction defined in twin gestation and how is it categorized?

Answer 8

EFW less than the 10th percentile and/or discordance greater than 25%

Question 9

When do you deliver type 2 selective fetal growth restriction in monochorionic twin pregnancy?

Answer 9

• Type 2 : persistent absent/reverse end diastolic velocity
• can offer selective cord occulsion of growth restricted fetus (higher survival but one baby)
• Deliver at 28 weeks

Question 10

When do you deliver type 1 selective fetal growth restriction?

Answer 10

Type 1 means normal or decreased end diastolic velocity.

Deliver at 34 weeks

Question 11

When do you deliver type 3 selective fetal growth restriction in monochorionic twin gestation?

Answer 11

Intermittent doppler dysfunction

Unpredictable clinical course

Deliver at 32 weeks

Question 12

Monozygotic splitting and type of twining:

Answer 12

Question 13

What is the significance of vanishing twin?

Answer 13

• occurs in up to 30% of pregnancies
• increased risk for fetal aneuploidy up to 60%

Question 14

What interventions decrease rate of preterm birth in unselected twin gestation?

Answer 14

none

Question 15

Does vaginal progesterone reduce preterm birth in twins with short cervix?

Answer 15

Vaginal progesterone reduced the rate of preterm birth in twin gestation with cervical length less than 25mm

Question 16

Can cerclage be placed in twin pregnancy?

Answer 16

shared decision making. retrospective cohort studies analyzed by Li say yes and only if cervical length is less than 1.5cm and or if the patient is 1cm dilated

Question 17

Percentage of mono-di and when mono-di split

Answer 17

Question 18

Twin position

Answer 18