Multiple pregnancy Flashcards
Yellow/green
Incidence of multiple pregnancy?
1 in 65 live births (increase over time due to fertility treatments)
What are
a) DCDA twins?
b) MCDA twins?
c) MCMA twins?
d) Conjoined twins?
a) dichorionic diamniotic twins - most common, non-identical, usually dizygotic from 2 eggs and 2 sperm, often related to IVF
b) monochorionic diamniotic twins - two separate sacs; identical and monozygotic (fertilized from one egg that then divides). shared placenta so inc risk of TTTS
c) monochorionic monoamniotic twins - 1 sac (rare), high risk of cord entanglement and foetal loss; identical, monzygotic, shared placenta = risk of TTTS
d) very rare, resulting from late/incomplete division of monozygotic pregnancy
What are predisposing factors for twins?
Previous twins FHx twins (dizygotic only) Increased maternal age Induced ovulation/IVF Racial origin (1 in 23 for Nigerian Yoruba women, 1 in 150 Japanese)
What are the common presenting features for multiple pregnancy?
In early pregnancy, uterus large for dates
Hyperemesis
Polyhydramnios
What signs may be elucidated?
> 2 poles felt
Multiplicity of foetal parts felt
2 foetal hearts heard
USS confirms diagnosis (11-14w distinguishes DCDA from MCDA/MCMA)
What sign is seen on USS in DCDA twins?
Lambda sign
What complications may occur in multiple pregnancies?
Polyhydramnios
Pre-eclampsia (10% singleton pregnancies; 30% in twin pregnancies)
Anaemia (inc iron and folate requirement)
APH incidence rises (abruption and p.praevia)
Gestational diabetes
Operative delivery
Congenital malformation (amniocentesis more risky in multiple pregnancy)
Stillbirth (MCMA>MCDA>DCDA)
What are the foetal complications of multiple pregnancies?
Raised perinatal mortality
Prematurity
FGR
TTTS - placental vascular anastomosis in monochorionic pregnancies (treatment with ablation by laser coagulation in utero)
Rarely, foetus papyraceous (foetal death in utero, shrinking and mummification) may be delivered prematurely
What can be performed if one foetus has congenital abnormalities?
Selective foeticide (with intracardiac KCl) best used before 20w
What complications may present in labour?
PPH Malpresentation (Ce/Ce and Ce/Br each have incidence of 40%) Vasa praevia rupture Cord prolapse Placental abruption Cord entanglement (esp monoamniotic)
What is the standard management of multiple pregnancy?
USS at 11 and 13w for viability, chorionicity, nuchal translucency, malformation
Monthly monitoring from 20w (2w if monochorionic: membrane folding may suggest TTTS) and name twins left and right
Refer to tertiary centre if discordant growth (>25%, suggests TTS)
Discuss delivery planning
Postnatal support groups
What can be done in twin pregnancies with maternal anaemia?
FBC taken at booking, 20w, 28w, 34w
Treat if Hb <11.5 at any stage with ferrous sulphate 200mg PO BD
How can congenital malformation be managed in twin pregnancy?
Folic acid 5mg PO OD throughout pregnancy
Screen for chromosomal abnormalities (e.g. nuchal translucency for Down’s); second trimester screening may be performed in twins but not in triplets
Anomaly scan should be performed at 18-20+6as in singletons and extended cardiac views performed
How can HNT/pre-eclampsia be managed in twin pregnancy?
Offer aspirin to any women with any other risk factor for HNT to reduce risk
BP and urinalysis should be performed at every visit
How often should routine growth scans be performed in multiple pregnancy?
DCDA - every 4w from 24w (more frequent if concerns_
MCDA - every 2w from 16w (can be decreased after 26w when TTTS risk has passed)
Each twin should be annotated on first scan (e.g. twin 1 maternal right, twin 2 maternal left) to ensure growth assessed correctly
When should twins be delivered?
DCDA - elective delivery 37-38w
MCDA - elective delivery 36-37w
MCMA - elective CS 32w
What mode of birth should be used for twin pregnancies?
Uncomplicated twins (DCDA/MCDA) at term where twin 1 cephalic, vaginal birth offered (CS does not increase/decrease risk vs vaginal) Increased risk of morbidity of second twin at delivery (10% risk of CS even after successful vaginal birth of first twin) If first twin not cephalic - elective CS offered and administration of corticosteroids to mother (for prevention of RDS) is recommended
What problems are associated with multiple pregnancies from IVF?
Multiple birth (monozygotic) Older mother effects -Pre-eclampsia and pregnancy-induced HNT (PIH) -CS delivery -Diabetes in mother Donor egg problems (esp PIH) Genetic defects (esp Beckwith-Wiedermann syndrome) Low birthweight -Prematurity -FGR Vasa praevia Prematurity (twice as common as natural conceptions) Perinatal mortality Abnormality rates increased
What is TTTS?
Twin-twin transfusion syndrome is caused by abnormal vessels through the shared placenta resulting in blood flowing predominantly form one baby to another
One baby becomes donor and is malnourished; other becomes engorged with excess blood (can develop heart failure)
Are twins always genetically identical?
The majority of twins are dizygotic)fertilised by two separate sperm) so are not identical; the remaining third however are monozygotic, from mitotic division of a single zygote, so share some genetic characteristics
What maternal risks are particularly common in pregnancy?
Gestational diabetes
Pre-eclampsia
Anaemia
What are the foetal antenatal complications for all multiple pregnancies?
Mortality and morbidity (+ congenital abnormalities)
Miscarriage
Preterm labour
IUGR
What are the foetal antenatal complications for monochorinicity?
TTTS
Twin anaemia polycythaemia sequence (TAPS): marked Hb differences between twins without liquor volume abnormalities of TTTS; can follow incomplete laser ablation for TTTS
Twin reversed arterial perfusion (TRAP): rare
IUGR
Co-twin death (death of one MC twin causes acute transfusion from other twin due to hypotension of deceased twin; other twin becomes hypovolaemic and dies - not problem in DCDA as no shared blood supply)
If the twins are dizygotic, what are the genders likely to be?
DZ twins are always of different genders
