Multiple pregnancy Flashcards
How many pregnancies are multiple in the UK?
1 in 63
What are some factors which increase the chance of multiple pregnancy
Maternal age - use of assisted reproductive technologies
Ethnicity
Define dizygotic
Ovulation and fertilisation of 2 oocytes
Define monozygotic
Ovulation and fertilisation of a single oocyte with subsequent division of the zygote
How are twins defined?
Number of chorions (placentas) and amnions (sacs)
List and describe the 3 classifications of twins
MCMA - Monochorionic monoamniotic - 1 placenta, 1 amniotic sac
MCDA - Dichorionic monoamniotic - 1 placenta, 2 amniotic sacs
DCDA - Dichorionic diamniotic - 2 placentas and 2 amniotic sacs
Why is it important to define the type of twin pregnancy?
Risks are dependent on whether or not the twins share the same placenta or amniotic space
Describe how DCDA twins are formed
Either dizygotic or monozygotic twins with cleavage of the zygote in the first 3 days after fertilisation
Describe how MCDA twins are formed
Monozygotic twins with cleavage of the zygote 4-8 days after fertilisation
Describe how MCMA twins are formed
Monozygotic twins with cleavage of the zygote from the 8th-12th day after fertilisation
How is chronicity diagnosed?
USS
When is the optimal time to diagnose chronicity
In the first trimester after 7 weeks
Which sign on USS indicates dichorionic pregnancy
Lambda sign
Which sign on USS indicates monochorionic pregnancy?
T sign
What are the maternal risks from multiple pregnancy?
Miscarriage
Hyperemesis
Maternal haemodynamic changes - dilutional anaemia
Gestational hypertension and pre-eclampsia
Gestational diabetes
Venous thromboembolism
Complications in labour - higher risk of intervention, caesarean section
Post partum haemorrhage
What are the foetal risks from multiple pregnancy for all twin pregnancies?
Premature delivery Malposition Miscarriage/stillbirth Growth restriction Congenital abnormalities
What are the foetal risks from monochorionic pregnancy?
Selective IUGR Twin to twin transfusion syndrome Twin to twin polycythaemia sequence Twin reversed arterial perfusion sequence Higher rates of congenital anomalies Death of one twin
What is the foetal risk from a monoamniotic pregnancy?
Cord entanglement
Describe the antenatal care offered to women with multiple pregnancy
Referral to obstetrician and specialist twin midwife or twin clinic. Referral to TAMBA - charity which give good information
Increased scanning programme 2-4 weeks depending on the type of twin pregnancy
Fetal medicine cardiac scans for monochorionic twins
Early referral to fetal medicine in case of any discrepancies
Birth planning discussions
What percentage of MC twin pregnancies does twin to twin transfusion syndrome affect?
15%
What is twin to twin transfusion syndrome?
Vascular connection between the babies at the placenta - allowing blood to transfer from one twin to another and can become unbalanced
What effects does twin to twin transfusion syndrome have on the recipient twin?
Large
Fluid overload
Cardiac failure
Excess liquor - increased urine output
What effects does twin to twin transfusion syndrome have on the donor twin?
IUGR
Reduced liquor - reduced urine output
How is twin to twin transfusion syndrome managed?
Regular USS
Referral to specialist fetal medicine unit
Laser therapy - separate connections in the placenta using fetoscope and laser. Excess amniotic fluid is removed. However the imbalance can return so monitor throughout pregnancy
What are the risks of foetal surgery
Rupture of membranes
Preterm birth
When are uncomplicated DCDA twins delivered?
37-38 weeks
When are uncomplicated MCDA twins delivered?
36-37weeks
Which mode of delivery is used for DCDA twins?
Vaginal birth if one baby is in cephalic position
Induction of labour
However risk of emergency C section even after 1st twin born
C-section if 1st baby not in cephalic presentation
