Twins

Question 1

When there is 1 “placental mass” on US, with an upward or downward projection of placental tissue into the area where the amnion and chorion interface between 2 amniotic sac is suggestive of what chorinonicity?

Answer 1

Dichorionic

Referred to as “Lambda Sign” or “Twin Peak Sign”

Question 2

When the dividing membrane between two amniotic sacs is > 2 mm thick suggests what chorionicity?

Answer 2

Dichorionic

Question 3

Cleavage 3 days after fertilization

Answer 3

Dichorionic Diamniotic

Question 4

Cleavage 4-8 days after fertilization

Answer 4

Mono Di

Question 5

Cleavage 9-12 days after fertilization

Answer 5

Mono-Mono

Question 6

Cleavage >/= 13 days after fertilization

Answer 6

Conjoined Twins

Question 7

Dividing membrane is thin (< 2 mm) and membrane insertion to the placenta is at a right angle (T sign)

Answer 7

Monochorionic

Question 8

How much folate should a mom with twins take?

Answer 8

1 mg folate daily

Question 9

What staging system is used to diagnosis Twin-twin transfusion syndrome?

Answer 9

Quintero Staging

Question 10

Quintero Stage 1

Answer 10

MVP < 2 cm in donor sac
MVP > 8 in recipient sac

Question 11

Quintero Stage 2

Answer 11

Non visualization of fetal bladder in donor twin over 60 minutes of observation

Question 12

Quintero Stage 3

Answer 12

Absent or reversed UAD

Question 13

Quintero Stage 4

Answer 13

Hydrops in 1 or both twins

Question 14

Quintero Stage 5

Answer 14

Fetal demise in 1 or both twins

Question 15

In Monochorionic twins, when should surveillance for TTTS start?

Answer 15

16 weeks, Q2 weeks

Question 16

For Monochroinic twins- with the death of 1 twin, what is the risk of a neurologic abnormality in the surviving twin

Answer 16

18% chance if co-twin dies in utero after 14 weeks gestation

**the death of one twin causes hypotension in the other twin because of the placental anastomoses and causes neuro injury

Question 17

For Monochroinic twins- with the death of 1 twin, what is the risk of a death in the surviving twin

Answer 17

15% risk of death

Question 18

For Dichorinoic twins- with the death of 1 twin what is the risk of neurologic abnormality in the surviving twin?

Answer 18

1% risk of neuro injury if co-twin dies after 14 weeks

Question 19

For Dichorinoic twins- with the death of 1 twin what is the risk of death in the surviving twin?

Answer 19

3% risk of death in the surviving twin

Question 20

What is the incidence of preterm birth in twins in the US?

Answer 20

59% before 37 weeks
11% before 32 weeks

Question 21

Recommended delivery for Di-Di twins

Answer 21

38 weeks
*Vaginal delivery after 32 weeks if presenting twin is cephalic

Question 22

Recommended delivery for Mono-Di Twins

Answer 22

34w0d-37w6d

Question 23

Recommended delivery for Mono-Mono twins

Answer 23

32 to 34 weeks

C-SECTION

*Up to 80% perinatal mortality primarily secondary to cord entanglement

Question 24

General twin management

Answer 24

Add 300 kcals to diet
1 mg Folate
Supplement with Oral Fe
US at 11-14 wks to determine chorionicity
Labmda sign = dichorionic
T sign = monochorionic

Offer Genetic counseling/aneuploidy screening
Twins at increased risks of anomalies
(especially monochorionic)
NIPT not as accurate, NT is accurate

Di-Di:
Anatomy scan
Serial growth US
Antenatal testing at 36 wks if uncomplicated

Monochorionic:
MFM consult
Screening US starting at 16 wks Q2 weeks to assess for TTTS
Detailed anatomy
Fetal ECHO. Increased risk of CHD

Mono-mono:
Inpatient at 24-28 wks
Antenatal surviellance, serially growth
Delivery at 32-34w by CS

Mono-di:
Antental surviellence outpatient at 32w
Delivery 34-38w

Question 25

Maternal Risks w/ Twins?

Answer 25

Hyperemesis
GDM
Pre E
Acute Fatty liver of pregnancy
Anemia/PPH
C/S
Postpartum Depression

Question 26

Fetal Risks of twinning

Answer 26

Increased risk of aneuploidy compared to singletons
- NIPT is less sensitive, cannot specify affected twin, and has a higher rate of test failure
- Recommend NT (not affected by twinning)

Increased risk of congenital malformations
- Increase folic acid to 1 mg
- Anatomy scan 18-20
- If monochorionic will need fetal ECHO

Preterm birth and resultant infant morbidity + mortality
- Intraventricular hemhorrage
- Periventricular leukomalacia/Cerebral palsy
- NEC
- Neec for respiratory support

Question 27

Requirements for vaginal deliveries of twins?

Answer 27

NOT mono-mono
Twin A is vertex
GA > 32 weeks
EFW > 1,500 g
Less than 20% growth discordance
Delivery in OR, w/ ability to convert to CS