Multiple Pregnancy

Question 1

What is the incidence of twins and triplets?

Answer 1

Twins = 1 in 80
Triplets = 1 in 1000
Incidence increasing due to fertility treatments

Question 2

List the types of multiple pregnancy

Answer 2

1. Dizygotic twins

2. Monozygotic twins

Question 3

What are the key points about dizygotic twins?

Answer 3

1. 2/3 of all multiple pregnancies
2. Fertilisation of different oocytes by different sperm
3. May be of different sex
4. No more genetically similar than siblings from different pregnancies

Question 4

What are the key points about monozygotic twins?

Answer 4

1. Mitotic division of single zygote into ‘identical twins’
2. Sharing of amnion or placenta depends on time of division:
   - Division before day 3 = dichorionic diamniotic
   - Between days 4-8 = monochorionic diamniotic
   - Later division (9-13) = monochorionic monoamniotic
   - Incomplete division = conjoined twins

Question 5

What is the aetiology behind multiple pregnancy?

Answer 5

1. Assisted conception
2. Genetic factors
3. Increasing maternal age and parity

Question 6

How can we diagnose multiple pregnancy?

Answer 6

1. Vomiting may be more marked in early pregnancy
2. Uterus larger than expected for dates and palpable before 12wks
3. Most diagnosed at US

Question 7

List the maternal complications of multiple pregnancy

Answer 7

1. All obstetric risk exaggerated
2. GDM + pre-eclampsia more frequent
3. Anaemia

Question 8

List the fetal antenatal complications of all multiple pregnancies

Answer 8

1. Greater mortality and long term handicap:
   - IUGR
   - Preterm delivery
   - Monochorionicity
2. Miscarriage:
   - One twin early on
   - Increased late miscarriage
3. Preterm labour
4. IUGR
5. Congenital abnormalities:
   - More common per baby in MC twins

Question 9

List the complications of monochorionicity

Answer 9

1. Twin-twin transfusion syndrome (TTTS)
2. Twin anaemia polycythemia sequence (TAPS)
3. Twin reversed arterial perfusion (TRAP)
4. IUGR more common
5. Co-twin death
6. Monoamniotic twins - cord entanglement and in utero demise due o shunting of blood between two babies

Question 10

What is twin-twin transfusion syndrome (TTTS)?

Answer 10

1. Only in MCDA twins
2. Unequal blood distribution through vascular anastomoses of the shared placenta
3. Staged according to Quintero in stages 1-5
4. High risk of in utero death or severely preterm delivery

Question 11

What happens to the ‘donor twin’ in TTTS?

Answer 11

1. Volume depleted
2. Develops anaemia
3. IUGR
4. Oligohydramnios

Question 12

What happens to the ‘recipient twin’ in TTTS?

Answer 12

1. Volume overloaded
2. May develop polycythemia
3. Cardiac failure
4. Massive polyhydramnios

Question 13

Describe the Quintero Classification

Answer 13

Stage I:
- Significant discrepancy in amniotic fluid volume
- Bladder of donor twin visible
- Doppler studies normal
Stage II:
- Bladder of donor twin is not visible
- Doppler studies not critically abnormal
Stage III:
- Doppler studies are critically abnormal in either the donor or recipient twin
- Abnormal or reversed end-diastolic velocities of the umbilical artery in the donor
- Abnormal venous Doppler velocities in the recipient
Stage IV:
- Ascites, pericardial or pleural effusion
- Scalp oedema or overt hydrops present unusally in recipient
Stage V:
- One or both babies are dead

Question 14

How is TTTS managed?

Answer 14

• Fetoscopic laser coagulation is the treatment of choice if diagnosed before 24wks
• Solomon technique (complete ablation along vascular equator rather than selective ablation) is preferred technique
• If complicated by this after 26wks DELIVER
• Survival of both twins = 50%; one twin = 80%

Question 15

What is twin anaemia polycythemia sequence (TAPS)?

Answer 15

1. Marked haemoglobin differences between MC twins in absence of liquor volume changes characteristic of TTTS
2. Consequence of small placental anastomoses
3. Can follow incomplete laser ablation for TTTS

Question 16

What is twin reversed arterial perfusion (TRAP)?

Answer 16

1. Rare

2. Abnormal, often acardic fetus is perfused by a normal ‘pump’ twin which is at risk of cardiac failure

Question 17

What is IUGR like in monochorionic twin pregnancies?

Answer 17

• Selective IUGR with intermittent absent or reversed end diastolic flow
• Umbilical artery waveform of smaller twin very erratic
• Growth discordancy

Question 18

What happens when there is co-twin death in monochorionic twin pregnancies?

Answer 18

1. One of twins dies, the drop in its BP allows acute transfusion of blood from the other twin
2. Rapidly leads to hypovolaemia and death or neurological damage (30%)
3. Survivor of dichorionic twin pregnancy not at risk as circulation not shared

Question 19

List the intrapartum complications of multiple pregnancies

Answer 19

1. Malpresentation of first twin - 20%; C-section
2. Fetal distress in labour - second twin delivered has increased risk of death (5x); second twin may present as breech
3. PPH (10%)

Question 20

What is the standard antepartum management of all multiples?

Answer 20

1. General:
   - Pregnancy considered high risk
   - Consultant led care
   - Iron and folic acid supplements
   - Low-dose aspirin if other risk factors for PET
   - Discuss postnatal home help
2. Early US:
   - Chorionicity must be accurately determined in first trimester
   - Dichorionic twins = lambda sign
   - Monochorionic twins = T sign
   - Twins of opposite gender always dizygotic
3. Identification of risk for preterm delivery:
   - TVUS of cervical length not advised
   - PV progesterone or cervical cerclage not useful in multiple pregnancy
4. Identification of IUGR:
   - US examinations and consultations every 4wks from 24wks to 36wks and weekly thereafter (uncomplicated DC twin pregnancy)
5. Timing of delivery:
   - Delivery at 38wks for DC twins
   - Delivery at 37wks for uncomplicated MC twins

Question 21

What is the antepartum management specific to MC twins?

Answer 21

Uncomplicated MC twin pregnancy = antenatal visits every 2-3wks from 16wks to delivery

Question 22

How are higher order multiple pregnancies managed antepartum?

Answer 22

1. Surveillence = according to chorionicity

Question 23

What modes of delivery are used in multiple pregnancy and when are they used ?

Answer 23

1. C-section:
   - If first fetus is breech or transverse lie
   - If higher order multiples
   - If there have been antepartum complications
2. Vaginal delivery:
   - When first fetus is cephalic

Question 24

How is the delivery managed?

Answer 24

1. CTG advised
2. Epidural analgesia helpful
3. Good communication with and comfortable position for mother
4. Contractions often diminish after first twin
5. Perform ECV if lie of second twin not longitudinal
6. Rupture membranes once head or breech of second twin enters pelvis and pushing recommences
7. Malpresentation of second twin = C-section
8. Fetal distress or cord prolapse = vaginal delivery expedited with a ventouse or breech extraction (general, epidural or spinal anaesthesia)
9. Prophylactic oxytocin infusion to prevent PPH