Twins Flashcards
How many stages in quintero staging system for TTTS
Stages 1 to 5
Complications seen in Monochorionic twins
Twin to twin transfusion syndrome TTTS
Single intrauterine death
Twin anaemia polycythemic sequence TAPS
Selective growth restriction SGR
Twin reverse arterial perfusion TRAP
What is twin to twin transfusion syndrome TTTS?
Unidirectional vascular artery-vein anastomoses in placental bed.
Causes haemodynamic imbalance within the twin circulation as one twin receives more blood than the other
Key features of TTTS on USS?
Significant amniotic fluid discordance - oligo DVP <2cm in donor and poly DVP >8cm in recipient
Discordant bladder appearances - no urine in donor fetal bladder
Haemodynamic and cardiac compromise in both twins
Stage 1 TTTS?
Oligohydramnios and Polyhydramnios
Donor bladder is visible
Stage 2 TTTS
Donor bladder not visible
Severe oligohydramnios due to anuria
Dopplers OK
Stage 3 TTTS
Doppler studies ABNORMAL
Donor has abnormal umb art doppler
Recipient has abnormal venous doppler (e.g. reversed flow in ductus venosis)
Stage 4 TTTS?
Ascites, pericardial/pleural effusion, scalp oedema, hydrops
Stage 5 TTTS?
One or both babies have died
How is TTTS treated?
Laser ablation of placental vascular anastomoses <26weeks
Amnioreduction is 2nd line
In treated TTTS, what is the follow up and delivery plan?
Weekly USS
Fetal cardiac USS
Deliver 34-36weeks
Morbidity in single intrauterine death in MC twins?
50% intact survivors
25% co-twin death
25% major neurological sequelae
MRI 4 weeks after twin death to look for co-twin brain damage
When to delivery uncomplicated MCDA
From 36 weeks
When to deliver MCMA twins?
32 weeks LSCS
What is selective growth restriction in MC twins?
EFW discordance of >20% due to differing placental territories between each twin
Classification of sGR (selective growth restriction)
Type 1, 2, 3
Type 1 sGR
Growth discordance
Normal dopplers
Type 2 sGR
Growth discordance
Absent or reversed end-diastolic velocities in 1/2 fetuses
Delivery by 32w
Type 3 sGR
Growth discordance
Cyclical umbilical artery diastolic waveforms - positive>absent>reversed over minutes
Delivery by 32w
Treatment for sGR in MC twins?
Laser ablation
Delivery if abnormal dopplers and >26w
Consider fetal reduction
What is twin anaemic polycythaemia sequence TAPS?
A form of TTTS with discordance in Hb between twins but no significant amniotic fluid discordance.
Occurs due to slow transfusion of blood from donor to recipient through SMALL arteriovenous anastomoses
Occurs in 2% of MCDA twins.
More likely to occur after laser ablation for TTTS
How to diagnose TAPS on USS?
Anaemic baby has raised MCA PSV, dilated heart
Polycythaemic baby has decreased MCA PSV, starry sky liver
Which baby is more likely to have neurodevelopmental delay in TAPS?
Polycythaemic twin
How to manage TAPS?
Laser ablation
IU blood transfusion
Deliver 30-32weeks
What is twin reversed arterial perfusion TRAP sequence?
Acardiac twin is perfused by the other twin through a large arterial anastomosis on the placenta
What proportion of MC twins does TRAP occur in?
1%
Why is TRAP so bad?
50% of pump twins die before/after birth due to congestive heart failure
How to treat TRAP?
Selective feticide of acardiac twin
What is the lambda sign and what does it represent in a twin pregnancy?
Dichorionic twins - thicker and V shaped
What is the T sign and what does it represent in a twin pregnancy?
Monochorionic twins - thinner membrane
What proportion of twin pregnancies are monochorionic?
30%
How do you perform combined screening in twins?
As normal
90% detection in DCDA twins
MC twins have a higher FPR because raised NT in one twin is an early manifestation of TTTS. Risk is calculated for each fetus and averaged.
Risk of fetal death in MCMA twins?
Up to 70%
Ultrasound regime for MC twins?
2 weekly from 16 weeks
