Multiple Pregnancy Flashcards
What percentage of twin pregnancies are dizygotic?
70%
What is the chorionicity and amnionicity of dizygotic twins?
They are dichorionic (have a placenta per twin) and diamniotic (have its own amniotic membrane)
How does the age of splitting of monozygotic twins affect their chorionicity and amnionicity?
IF BEFORE 8 CELL STAGE (day 3) placenta and amnion will develop separately = DICHORIONIC and DIAMNIOTIC
SPLITTING AT BLASTOCYST STAGE (4-8 days) MONOCHORIONIC DIAMNIOTIC (most common)
SPLITTING AT 8-14 days = MONOCHORIONIC MONOAMNIOTIC
SPLITTING >14 DAYS - usually result in conjoined twins
What are some maternal complications associated with multiple pregnancies?
Hyperemesis - increased hCG levels
Anaemia - more likely - further haemodiltuion d/t increased plasma
APH - placenta praevia and abruption both more likely
Pre-Eclampsia - 3-4X more likely in multiple pregnancies
What are some fetal complications associated with multiple pregnancies?
Structural anomalies much more common with MONOCHORIONICITY (cardiac and neural tube defects most common)
Chromosomal abnormality
Premature birth (typically 37-38 weeks) - again more common in monochorionic
IUGR (growth slows after 28-30w)
Twins with one fetal death
TTTS (twin-twin transfusion syndrome)
What is TTTS? What are the risks? How is it managed?
Twin-Twin Transfusion Syndrome.
Net blood flow from one twin to the other due to aterio-venous anastomoses in the placenta
FOR RECIPIENT TWIN: hyperdynamic circulation with risk of cardiac failure and polyhydramnios
FOR DONOR TWIN: oliguria and oligohydramnios
80% pregnancy loss rate without treatment
Amniotic fluid drainage and laser ablation of anastomoses have both been shown to be useful
How do we manage multiple pregnancies?
Determine chorionicity early - hard to do as foetuses get bigger
Counsel parents - sometimes twin doesn’t survive
Give additional visits depending on chorionicity
Monitor for complications (pre-eclampsia, anaemia)
Discuss delivery options at 32 weeks
What additional visits will women with multiple pregnancies have?
MONOCHORIONIC
- every 2 weeks from 16-24w to monitor for TTTS
- detailed structural scan at 18 weeks
- Detailed fetal cardiac scan at 20-22
- Every 2 weals from 24 weeks for fetal growth assessment
DICHORIONIC
- Detailed structural survey at 18w
- Every 2 weeks from 24 weeks for fetal growth assessment
What does the T sign on USS mean?
T sign
- ONE PLACENTA, ONE SAC
- monochorionic, monoamniotic
What does the lambda sign on USS mean?
Lambda sign
-TWO PLACENTA (dichorionic)
At birth, how are twins usually orientated?
Cephalic/Cephalic (40%)
Cephalic/Breech (40%)
Breech/Cephalic (10%)
Other e.g. transverse (10%)
When should multiple pregnancies be delivered?
- Induce at 37 weeks but only if suitable for vaginal delivery (twin 1 HAS to be cephalic)
- If 1st twin not cephalic then carry out a C/S at 38 weeks
How do we monitor during twin deliveries?
Continuous monitoring is really important but it is equally important to make sure that when using a CTG we are not monitoring the same twin twice…
Therefore one twin (twin 2) is usually monitored using the CTG and the other (twin 1) is monitored using a fetal scalp electrode
What measure should always be taken during twin delivery?
Obstetrician should always be present as well as a paediatrician, a midwife and an anaesthetist
Always have a syntocinon infusion ready just in case uterine activity decreases after the first delivery
How do we deliver twin one and twin two?
Twin one should be delivered normally and after this it is often helpful to stabilise the lie of twin two as longitudinal by abdominal palpation
The membranes of twin two should NOT be broken until it descends into the pelvic cavity
