Multiple Pregnancy Flashcards
Prevalence of multiple births
-Twins account for approximately 1.5%
-Higher multiples occur in 1/2500
Risk factors for multiple births
-Assisted reproductive techniques
-High parity
-Afro-Caribbean ethnicity
-Maternal family history
-Higher maternal age
Helene’s rule in multiple pregnancy
-Twins were expected in 1/80
-Triple 1/80X80
-Quadruplets 1/ 80x80x80
Describe zygocity (types of twins)
-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
Aetiology of twins
-Dizygotic twins may arise spontaneously from the release of two eggs at ovulation
=Familial
=Racial
=Increasing maternal age
=Induction of ovulation
=IVF
Describe monozygotic twins
-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
Types of monozygotic twins
-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
Types of conjoined twins
-Rare 1:70,000 deliveries. The majority are thoracopagus.
=Anterior (thoracopagus)
=Posterior (pygopagus)
=Cephalic (craniopagus)
=Caudal (ischiopagus)
Maternal physiological adaption for multiple pregnancy
-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
Complications of multiple pregnancy
1- preterm labour
2- pregnancy-induced hypertension
3- anaemia
4- polyhydramnios
5- congenital malformation
6- growth restriction
7- miscarriage
8- high perinatal mortality & morbidity
Risk of fetal abnormalities in twins
-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
Chromosomal defects in twins
- MCDA (MZ- DCDA) either both or none of the twins will be affected ( the risk is based upon maternal age)
- DCDA twins the risk will be twice that of singleton pregnancy. PNMR of MCDA is 5 times that of DCDA(120 VS24/ 1000 births)
Selective fetocide in twins
-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
Describe twin to twin transfusion syndrome
-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
Describe the donor fetus in twin to twin transfusion syndrome
- Hypovolaemia and hypoxia
- Growth restriction
- Oliguria
- Oligohydramnios
Describe the recipient fetus in twin to twin transfusion syndrome
- Hypervolaemia
- Polyhydramnios
- Myocardial damage
- High output failure
More at risk of failure
Quintero classification stage 1
-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
Quintero classification stage 2
-Polyhydramnios and Oligohydramnios
-Bladder is no longer seen in the donor twin during the ultrasound evaluation
Quintero classification stage 3 to 4
Worsening features including fetal demise
What is TAPS?
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
Determining gestational age and chorionicity
-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
Antenatal advice for multiple pregnancy
-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
Ultrasound in antenatal management
-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
Intra-partum management of twins
-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
Common presentations in twins
-Cephalic/cephalic 60%
-Cephalic/breech 20%
-Breech/cephalic 10%
-Breech/breech 10%
Indications for C.S. for multiple pregnancy
-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.
Requirements for twin delivery
-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
Complications in labour multiple pregnancy
-Maternal
=PPH- traumatic and atonic
=Trauma
=Operative delivery
-Fetal
=Trauma
=Preterm birth complications
Describe Internal Podalic Version
-Experienced operator
-EFW > 1500 gm
-Adequate liquor
-Available anaesthesia for effective uterine relaxation
-Simultaneous preparation for emergency C/S
