Multiple Pregnancy

Question 1

Prevalence of multiple births

Answer 1

-Twins account for approximately 1.5%
-Higher multiples occur in 1/2500

Question 2

Risk factors for multiple births

Answer 2

-Assisted reproductive techniques
-High parity
-Afro-Caribbean ethnicity
-Maternal family history
-Higher maternal age

Question 3

Helene’s rule in multiple pregnancy

Answer 3

-Twins were expected in 1/80
-Triple 1/80X80
-Quadruplets 1/ 80x80x80

Question 4

Describe zygocity (types of twins)

Answer 4

-Non identical twins (dizygotic twins)
=Always have two separate placentae (DC)
=Separate amniotic cavities (DA)
=Either the same or different sex pairing

-Identical twins (monozygotic)
=Arise from fertilization of single egg
=Always of same sex
=Either MC or DC

Question 5

Aetiology of twins

Answer 5

-Dizygotic twins may arise spontaneously from the release of two eggs at ovulation
=Familial
=Racial
=Increasing maternal age
=Induction of ovulation
=IVF

Question 6

Describe monozygotic twins

Answer 6

-Arise from a single fertilized ovum that splits into two identical structures
-The incidence of monozygotic twins 1/250 - not influenced by race ,family history or parity

Question 7

Types of monozygotic twins

Answer 7

-Split within 3-4 days of fertilization- DCDA (30%): 2 placenta 2 sac
-Split within 4-8 days of fertilization- MCDA (70%): 1 placenta 2 sacs
-Split within 8-14 days of fertilization- MCMA
-Split within >14 days of fertilization- Conjoined twins

Question 8

Types of conjoined twins

Answer 8

-Rare 1:70,000 deliveries. The majority are thoracopagus.
=Anterior (thoracopagus)
=Posterior (pygopagus)
=Cephalic (craniopagus)
=Caudal (ischiopagus)

Question 9

Maternal physiological adaption for multiple pregnancy

Answer 9

-Increased blood volume and cardiac output.
-Increased demand for iron and folic acid.
-Maternal respiratory difficulty.
-Excess fluid retention and oedema.
-Increased incidence of supine hypotension

Question 10

Complications of multiple pregnancy

Answer 10

1- preterm labour
2- pregnancy-induced hypertension
3- anaemia
4- polyhydramnios
5- congenital malformation
6- growth restriction
7- miscarriage
8- high perinatal mortality & morbidity

Question 11

Risk of fetal abnormalities in twins

Answer 11

-The risk of fetal abnormalities – Singleton x 2

-DCDA twins - risk of structural abnormalities is similar to that for singleton pregnancy
-MCDA twins- risk 4 X that of singleton pregnancy
-Abnormality in one fetus can be managed expectantly or by selective fetocide of the affected fetus
-When the abnormality is not lethal- weigh the risk of loss of a normal fetus from fetocide related complications

Question 12

Chromosomal defects in twins

Answer 12

1. MCDA (MZ- DCDA) either both or none of the twins will be affected ( the risk is based upon maternal age)
2. DCDA twins the risk will be twice that of singleton pregnancy. PNMR of MCDA is 5 times that of DCDA(120 VS24/ 1000 births)

Question 12

Selective fetocide in twins

Answer 12

-DCDA twins selective fetocide is associated with risk of preterm loss
-MCDA twins selective fetocide is dangerous for the second twin so cord occlusion techniques preferable

Question 13

Describe twin to twin transfusion syndrome

Answer 13

-Chronic shunt occurs ,the donor bleeds into the recipient so one is pale with oligohydramnios while the other is polycythaemia with hydramnios
-If not treated death occurs in 80-100% of cases

Question 14

Describe the donor fetus in twin to twin transfusion syndrome

Answer 14

1. Hypovolaemia and hypoxia
2. Growth restriction
3. Oliguria
4. Oligohydramnios

Question 15

Describe the recipient fetus in twin to twin transfusion syndrome

Answer 15

1. Hypervolaemia
2. Polyhydramnios
3. Myocardial damage
4. High output failure

More at risk of failure

Question 16

Quintero classification stage 1

Answer 16

-Oligohydramnios in the donor’s sac
-MVP of 2 cm or less

-Polyhydramnios in the recipient’s sac
-MVP of fluid of 8 centimetres or more.
-The bladder of the donor baby is still seen

Question 17

Quintero classification stage 2

Answer 17

-Polyhydramnios and Oligohydramnios
-Bladder is no longer seen in the donor twin during the ultrasound evaluation

Question 18

Quintero classification stage 3 to 4

Answer 18

Worsening features including fetal demise

Question 19

What is TAPS?

Answer 19

Twins anaemia polycythemia sequence
-5% of MCDA twins
-A discordance in haemoglobin is its hallmark
- Ultrasound scan shows a significant difference (more than1 multiple of the median [MoM]) in the PSV-MCA
- Anaemic donor has increased blood velocities in the brain(>1.5 MoM), and
- Polycythemia recipient has decreased velocities (<0.8MoM).

-10% of TTTS cases are accompanied by TAPS.
-Iatrogenic TAPS is a known complication if laser surgery for TTTS misses tiny anastomoses.
-Spontaneous as well as iatrogenic TAPS placentas typically have minuscule anastomoses through which a net transfer of red blood cells occur
- In contrast to TTTS, TAPS does not cause any discomfort.
-Therefore, to diagnose TAPS, we follow the PSV-MCA in both twins

Question 20

Determining gestational age and chorionicity

Answer 20

-An ultrasound scan should be offered when crown–rump length measures from 45 mm to 84 mm to:
=Estimate gestational age
=Screen for Down’s syndrome
=Determine chorionicity
-Assign chorionicity to foetuses to ensure consistency throughout pregnancy

Question 21

Antenatal advice for multiple pregnancy

Answer 21

-Fe supplements 200mgm daily
-Folic acid 800 mcgm daily
-Advice about risk of preterm labour (twins 40%, triplets75%), prelabour rupture of membranes preeclampsia (twins 10-20% and triplets 25-60%) and malpresentations
-Low dose Aspirin as per NICE guidelines
-Discuss deliver and pain relief in labour
-No place for cerclage, tocolysis or bed rest
-MCDA twins- Discuss TTTS and management

Question 22

Ultrasound in antenatal management

Answer 22

-12 week screening for T21
-20 week anomaly scan
-22 week cardiac scan for MCDA pregnancies
-DCDA- Fetal growth at 24, 28, 32 and 36 weeks
-MCDA- 2 weekly growth scans from 16 weeks to assess for development of TTTS

Question 22

Intra-partum management of twins

Answer 22

-DCDA twins are delivered by 37 weeks
-IOL if T1 is cephalic
=Mode of delivery depends on the size of the second twin and presence of growth discordance
-LSCS if T1 is non-cephalic.
-MCDA by LSCS at 36 weeks

Question 22

Common presentations in twins

Answer 22

-Cephalic/cephalic 60%
-Cephalic/breech 20%
-Breech/cephalic 10%
-Breech/breech 10%

Question 23

Indications for C.S. for multiple pregnancy

Answer 23

-Triplets or higher order
=weight < 2 kg
=discordant growth ( i.e.; IUGR or twin-twin transfusion, or discordant twins, twin 2 larger than 1)
= twin A: is non-vertex
=Conjoined Twins
=MCMA
=Previous Uterine scar
=During Labour: FTP, fetal distress, or if twin B transverse lie and IPV not possible
=Associated pregnancy complication i.e.; severe PIH, placenta previa.

Question 24

Requirements for twin delivery

Answer 24

-Ultrasound machine
-Operating theatre and staff ready
-Anaesthetist present
-Senior obstetrician, two midwives and Neonatologists
-Twin resuscitaires
-Ventouse/forceps to hand
-Blood grouped and saved
-Intravenous access
-Pre-mixed oxytocin infusion ready

Question 25

Complications in labour multiple pregnancy

Answer 25

-Maternal
=PPH- traumatic and atonic
=Trauma
=Operative delivery

-Fetal
=Trauma
=Preterm birth complications

Question 26

Describe Internal Podalic Version

Answer 26

-Experienced operator
-EFW > 1500 gm
-Adequate liquor
-Available anaesthesia for effective uterine relaxation
-Simultaneous preparation for emergency C/S