Twin pregnancies (Complete)

Question 1

What are the two main types of twins?

Answer 1

Monozygotic (Identical) [1/3rd of cases]

Dizygotic twins (Unidentical) [2/3rd of cases]

Question 2

What are the subtypes of monozygotic twins?

Answer 2

Dichorionic and diamniotic

• Split occurs day 0-4

Monochorionic and diamniotic

• Split occurs day 4-8

Monochorionic and monoamniotic

• Split occurs day 8-12

Question 3

What is the most common subtype of monozygotic twins?

Answer 3

Monochorionic and diamniotic (Same placenta and seperate amniotic sacs)

Question 4

What is the chorionicity and amnionicity of dizygotic twins?

Answer 4

Dichorionic and Diamniotic

Question 5

What type of twins may develop if splitting occurs post 12 days?

Answer 5

Conjoined twins (extremely rare)

Question 6

What are the main risk factors for twin pregnancy?

Answer 6

Infertility treatments (e.g. IVF)

Previous twins

Family history

Increasing maternal age

Multigravida

Race (e.g. Afro-Caribbean)

Question 7

Which type of twin pregnancies require more close monitoring?

Answer 7

Monozygotic twins (esp monochorionic, monoamniotic)

Due to increased risk of complications (e.g twin-transfusion syndrome)

Question 8

Twin-pregnancies are associated with increased risk of which foetal complications?

Answer 8

Increased perinatal mortality

Prematurity

Light-for-date babies

Malformations (e.g. Down’s syndrome, NTDs)

Question 9

Twin-pregnancies are associated with increased risk of which maternal complications?

Answer 9

Hyperemesis gravidarum

PPH

Malpresentation

Cord prolapse and entanglement

Hypertension

Pre-eclampsia

Gestational diabetes

Question 10

Monoamniotic, monochorionic monozygtoic twins are at highest risk of which complications?

Answer 10

Twin-transfusion syndrome

Pematurity and IUGR

Malformations

Spontaneous miscarriage and perinatal mortality

Question 11

What are some clinical signs of twin pregnancy?

Answer 11

Non-specific however may present with:

Hyperemesis gravidarum (excessive beta-hCG)

Larger pregnant abdomen

Question 12

What investigations are conducted for suspected twin pregnancy?

Answer 12

Bedside:

Pregnant abdomen exam: Large symphysis-fundal height

Bloods:

Beta-hCG: Higher levels

Imaging:

TV USS:

• T-sign: Monozygotic
• Lambda sign: Dizygotic twins

Question 13

What TV USS signs are suggestive of monozygotic twin pregnancy?

Answer 13

T-sign

Question 14

What TV USS signs are suggestive of dizygotic twin pregnancy?

Answer 14

Lambda sign

Question 15

How are twin pregnancies managed antenatally?

Answer 15

Monitoring:

Repeat FBC between 20-24 weeks and 28 weeks

• Check iron and folic acid deficiency

BP and OGTT

• Check for pre-eclampsia and gestational diabetes

Appointments:

Monozygotic: at 11 antenatal appointments (at least 2 with specialist) twice weekly

Dizygotic: 8 antenatal appointments (at least 2 with specialist) four weekly

Question 16

How are twin pregnancies managed during labour?

Answer 16

Monozygotic: Offer elective births from 36 weeks

Dizygotic: Offer elective births from 37 weeks

Offer- C section if first twin is not in cephalic presentation

Question 17

Vaginal birth in twin pregnancies with breech presntation is okay in which circumstances?

Answer 17

If the first twin is in cephalic presentation

If not then C-section reccomended